CA1101303A - Backflow prevention apparatus - Google Patents
Backflow prevention apparatusInfo
- Publication number
- CA1101303A CA1101303A CA330,412A CA330412A CA1101303A CA 1101303 A CA1101303 A CA 1101303A CA 330412 A CA330412 A CA 330412A CA 1101303 A CA1101303 A CA 1101303A
- Authority
- CA
- Canada
- Prior art keywords
- valve
- poppet
- chamber
- barrel
- spring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03C—DOMESTIC PLUMBING INSTALLATIONS FOR FRESH WATER OR WASTE WATER; SINKS
- E03C1/00—Domestic plumbing installations for fresh water or waste water; Sinks
- E03C1/02—Plumbing installations for fresh water
- E03C1/10—Devices for preventing contamination of drinking-water pipes, e.g. means for aerating self-closing flushing valves
- E03C1/106—Devices for preventing contamination of drinking-water pipes, e.g. means for aerating self-closing flushing valves using two or more check valves
-
- E—FIXED CONSTRUCTIONS
- E03—WATER SUPPLY; SEWERAGE
- E03C—DOMESTIC PLUMBING INSTALLATIONS FOR FRESH WATER OR WASTE WATER; SINKS
- E03C1/00—Domestic plumbing installations for fresh water or waste water; Sinks
- E03C1/02—Plumbing installations for fresh water
- E03C1/10—Devices for preventing contamination of drinking-water pipes, e.g. means for aerating self-closing flushing valves
- E03C1/108—Devices for preventing contamination of drinking-water pipes, e.g. means for aerating self-closing flushing valves having an aerating valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K15/00—Check valves
- F16K15/02—Check valves with guided rigid valve members
- F16K15/025—Check valves with guided rigid valve members the valve being loaded by a spring
Landscapes
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Public Health (AREA)
- Water Supply & Treatment (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Check Valves (AREA)
- Safety Valves (AREA)
Abstract
ABSTRACT
Two check valves in series with a zone between them are mounted between the supply pipe and discharge pipe, and a relief valve vents the zone to atmosphere under predetermined pressure conditions in the pipes. A valve poppet in the upstream check valve has a pressure affected piston chamber and contains an ejector nozzle which dis-charges fluid when the valve is open. The discharge passes through the zone and the velocity head is directed against a valve poppet in the downstream check valve.
The action of the ejector nozzle aspirates the pressure affected chamber in the upstream check valve to reduce the pressure drop when the valve is open. A valve poppet in the downstream check valve also includes a pressure affected piston area. In each check valve the flow restriction across the valve seat decreases more rapidly than the downstream flow restriction. Also, the outer surface of the valve poppet in the upstream check valve defines, with its stationamy barrel enclosure, a series of ribs and cavities which direct flow of fluid from the check valve through the ejector nozzle while minimizing flow into the aspirated chamber. A relief valve device connected to vent the zone to atmosphere has a valve stem subjected to a pressume differential between the inlet pressure to the upstream check valve and the reduced pressure in its aspirated chamber.
Two check valves in series with a zone between them are mounted between the supply pipe and discharge pipe, and a relief valve vents the zone to atmosphere under predetermined pressure conditions in the pipes. A valve poppet in the upstream check valve has a pressure affected piston chamber and contains an ejector nozzle which dis-charges fluid when the valve is open. The discharge passes through the zone and the velocity head is directed against a valve poppet in the downstream check valve.
The action of the ejector nozzle aspirates the pressure affected chamber in the upstream check valve to reduce the pressure drop when the valve is open. A valve poppet in the downstream check valve also includes a pressure affected piston area. In each check valve the flow restriction across the valve seat decreases more rapidly than the downstream flow restriction. Also, the outer surface of the valve poppet in the upstream check valve defines, with its stationamy barrel enclosure, a series of ribs and cavities which direct flow of fluid from the check valve through the ejector nozzle while minimizing flow into the aspirated chamber. A relief valve device connected to vent the zone to atmosphere has a valve stem subjected to a pressume differential between the inlet pressure to the upstream check valve and the reduced pressure in its aspirated chamber.
Description
3~3 Ihis invention relates to backflow prevention apparatus to be installed between a supply p;pe and a discharge pipe. Such devices are commonly used in water supply systems in order to insure that polluted water in a discharge pipe cannot flow in a reverse direction into a supply pipe. Such apparatus commonly employs an upstream check valve and a downstream check valve with a zone between them~ along with a relief val~e operated by differential pressure for venting the zone to atmosphere whenever the discharge pressure approaches the supply pressure within pre-determined limits.
According to one aspect of the invention, there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage ~rom the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet
According to one aspect of the invention, there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage ~rom the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet
2~ into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when sald valve poppet is lnitially moved away from said seat by fluid pressure 11l sald inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receivlng fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicat-ing with said chamber so that relatively rapid -fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose A -1- ~
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the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, the downs-tream check valve assembly having ~ :~
a valve poppet communicati.ng with the zone and positioned to receive t.he velocity head discharge from the upstream check valve assembly.
According to a second aspect of the invention there is provided in backflow prevention apparatus for installation bet~een a supply pipe .:
and a discharge pipe, the apparatus including upstream and downstream check ~:
valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes~ the improvement comprising, in combination: an inlet passage ;-:
from the supply pipe terminating in a stationary valve sest forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided Eor movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into seallng contact with said valve seat, said spring acting to create a pressure drop throug]l the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, an ejector nozzle on said valve poppet receiving fluid :Erom said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle ca~lses a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
According to a third aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe .
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and a discharge pi.l)e, the apparatus including upstream and downstream check valve assemb:lies with a zone ~etween t~em, and a relie:E valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary annular valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with saïd valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away ~rom said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, aspirator means receiving fluid :Erom said barrel when said valve poppet has separated from said valve seac, sa~-l aspirator means acting to reduce the pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across thé upstream check valve assembly, said relief valve device having a va~ve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
~ ccording to a fourth aspect of the inventi.on there is provided in backElow prevention apparatus :Eor :installa~ion betweon a s~lpply p:ipe and a discharge pipe, the apparatus inclucling upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary annular valve seat forming a part of the upsteam check valve asse~ly~ a stationary barrel positioned
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the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, the downs-tream check valve assembly having ~ :~
a valve poppet communicati.ng with the zone and positioned to receive t.he velocity head discharge from the upstream check valve assembly.
According to a second aspect of the invention there is provided in backflow prevention apparatus for installation bet~een a supply pipe .:
and a discharge pipe, the apparatus including upstream and downstream check ~:
valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes~ the improvement comprising, in combination: an inlet passage ;-:
from the supply pipe terminating in a stationary valve sest forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided Eor movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into seallng contact with said valve seat, said spring acting to create a pressure drop throug]l the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, an ejector nozzle on said valve poppet receiving fluid :Erom said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle ca~lses a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
According to a third aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe .
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and a discharge pi.l)e, the apparatus including upstream and downstream check valve assemb:lies with a zone ~etween t~em, and a relie:E valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary annular valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with saïd valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away ~rom said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, aspirator means receiving fluid :Erom said barrel when said valve poppet has separated from said valve seac, sa~-l aspirator means acting to reduce the pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across thé upstream check valve assembly, said relief valve device having a va~ve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
~ ccording to a fourth aspect of the inventi.on there is provided in backElow prevention apparatus :Eor :installa~ion betweon a s~lpply p:ipe and a discharge pipe, the apparatus inclucling upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary annular valve seat forming a part of the upsteam check valve asse~ly~ a stationary barrel positioned
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~,i co~lxially of said valve seat, a va.:lv~ poppet guided :Eor movement in said barrel toward and al~ay from sa;d va:lve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream chec~ valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seatl an ejector no~le on said valve poppet receiving fluid from said barrel when said valve poppe~ has separated from said valve seat, said ejector nozzle having a discharge end communicating with said chamber so that relatively rapid fluid flow from said ejector causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
~ccording to a ifth aspect of the invention there is provided in backflo~ prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermlned pressure conditions in the pipes, the ilnp~ovement comprisi.ng, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly -3a-... ~ :, :: , : . . .. , ':
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3~3 wilen said valve poppet is initi.ally moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, the downstream check valve assembly having a valve poppet communicating with the zone and positioned to receive the velocity head d;scharge from the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
According to a sixth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstr0am check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pres!sure conditions in the pipes, the improvement comprising, in combination: an inlet pass-age from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved a.way from said seat by fluid pressure D -3b-, .
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ln said in:Let passage, means cooperating with said barrel and said valve poppet to defiTIe a chamber remote from said valve seat, an ejector noz~le on said valve poppet receivîng fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet cooperating with said barrel to form two series of pockets and ribs symmetrical with respect to said ejector nozzle and acting to minimize flow from said seat into said chamber, said ejector nozzle having a discharge end communicating wlth said cllamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said :
1~ chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
According to a seventh aspect of the invention there is provided in a backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assembl:ies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, i.n combination: an inlet passage .
rom-the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly~ a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat~ a spring acting to move said valve poppet into sealing contact wlth said valve seat~ said sprlng actlng to create a pressure drop through the upstream check valve assembbly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector no~zle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve -3c-D
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poppct cooperating with saicl ~arrel to form pockets and ribs to produce circumferential flow o-E fluid on -tlle outer surEace of said valve poppet away from said ejector ~ozzle and thereby acting to minimize axial flow from said seat along said valve poppet into said chamber, said ejector nozzle having a discllarge end communicating with said chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
According toan eighth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downst~eam check valve assemblies wïth a zone between them, and a relie:E valve device for venting the zone to atmosphere under precletermined pressure conditions in the pipes, the ïmprovement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned within the body coaxially of said valve seat, a body having a removable cover, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, saicl valve poppet, stem, spring and retainer being axially insertable into said barrel as a unitary assembly in the absence of said cover, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said -3d-,' ' ' ' .
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va.lve seat, said ejector nozzle having a discharge end communicating with said spring chamber so tilat relatively rapid fluid flow from said ejector nozz:lc causc~s cl re~d~ction in f.luid press~lre in said spring chamber to oppose the action oE said sprïng and thereby reduce the pressure drop across the upstream check valve assem~ly.
According to a ninth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies w;~h a zone between ~hem~ and a relief valve device for venting the zone to atmosphere under prede~ermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the wpstream check valve assembly, a valve poppet guicled for movement toward and away from said valve seat, a first spring acting to move said valve poppet into sealing contact with saicl valve seat, said first spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage~ means cooperating with said valve poppet to define a chamber remote from said valve seat, aspirator means on said valve poppet receiving fluid when said valve poppet has separated from said valve seat, ancl acting to cause a reduction in Eluid pressure in said chamber to oppose the action of said first spring and thereby reduce the pressure dxop across ~he upstream clleck valve assembly, sai.d relief valve device having relatively movable valve parts for controlling flow from said zone to atmosphere, a second spring acting to cause relative movement of said valve parts toward open position, and di:Eferen- :
tial pressure mecms sensitive to pressure in said inlet passage and in said aspira~ed chamber for changing the effective force of said second D -3e-i. . .. . , ., ~ . , . . :
spring.
According to ~q tenth aspect o~ the invention there is provided backflow prevention apparatus for installation between a supply pipe and a discharge pipe, having in combination: a check valve assembly having an inlet passage from the supply pipe terminating in a stationary valve seat, a stationa.ry barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel ~oward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the check valve assembly when said valve poppet is initially moved away from sai.d seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formed be~ween said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stàtionary barrelJ the third chamber being formed downstream of said valve poppet and said barrel~ an ejector nozzle having an intake receiving flow from the first chamber when said valve poppet has separated from said valve seat, a discharge passage from said ejector nozzle communicating with said third chamber, and a space between its intake and its discharge passage connected to said second chamber so that relatively rapid flow from said ejector nozzle causes a reduction :in :Fluid pressure in sn:i.d seconcl chnmbcr to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
Accord:ing to an eleventh aspect of the invention there is provided a pressure differential valve assembly for installation between a supply pipe and a discharge pipe, comprising in combination: an inlet passage from the supply pipe terminati.ng in a stationary valve seat forming a D
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3~3 part of the valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided :for movelllent in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seatj said spring acting to create a pressure drop through the valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber ~eing formed between said valve seat and one side of said valve poppet, the second chamber being formed : .:
on the other side of said valve poppet and in cooperation wlth sa.id stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, aspirator means receiving fluid from said first chamber when said valve poppet has separated from said valve seat, said aspirator means havIng a discharge passàge communicating with said third chamber, said aspirator means being connected to said second chamber so that relatively rapid flow from said aspirator means causes a reduction in fluid pressure in said second chamber to oppose the action :; :
of said spring and thereby reduce the pressure drop across the valve assembly.
According to a twelfth aspect of the inventlon there is provided in backflow prevention apparatus or installat.ion between n supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure condit:ions in the pipes, the :Lmprovement comprising, in combination: an inlet passage from the supply pi.pe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for -3g-~ .
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movement in said barrel -toward and away Erom said valve seat, a spring acting to move said valve ~poppet into seali:ng contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure ïn said ïnlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first :
chamber being formed between said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, aspirator means receiving fluid from said :Eirst chamber when said valve poppet has separated from said valve seat, said aspirator means acting to reduce the pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said second chamber.
According to a thirteenth aspect of the invention there is provided in backflow prevention apparatus for ins~allation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assembli.es with a zone between them, and a relie:E valve device ~or venting the zone to atmosphere ~mder predeterm:ined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part o~ the upstream check valve assembly, a stationary barrel ~`
positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move saïd valve poppet into sealing contact with said valve seat, said -3h-;
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3~3 spring acting to create a pressure drop through the upstream check valve assembly ~ en sai(Z valve poppet is ;nit;ally moved away Erom said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formcd between said valve seat and one side of said valve poppet, :
the second chamber being formed on the other side of said -valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, an ejector nozzle having an intake receiving flow from the first chamber when said valve poppet is separated from said valve seat, a discharge passage rom said ejector nozzle communicating with said third chamber, and a space between its intake and its dîscharge passage connected to said second chamber so that relatively rapid flow from said ejector nozzle causes the reduction in pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
According to a fourteenth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including a differential check valve ~-assembly for connection to the supply pipe, the improvement comprising, .
in combination: a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet having pockets and ribs cooperating with said barrel to produce circumferential Elow of fluid on the outer -3i-D ~ -~13~1 s~lrface of saicl vaLve poppe-t away from said ejector noz~le and thereby acting to minimize axial flo~ from sai.d valve seat along said valve poppet into said chamber, said ejector nozzle llaving a portion communicat-ing ~ith said cha~,ber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring.
According to a fifteenth aspect of the invention there is provided in a check valve assembly, the improvement comprising, in combination: a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a removable cover secured relative to said barrel, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into seal-ing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem, spring and retainer being axially `~
insertable into said ~arrel as a unitary assembly in the absence of said removable cover, aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means communicat.ing with said spring chamber so that relatively rapid fluid flow through said aspirator means causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
According to a sixteenth aspect of the invention there is provided in a check valve assembly, the improvement comprlsing, in combination: a stationary body, a stationary barrel positioned within -3j-.
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the ~ody and having a coaxial valve seat thereonJ a removable cover secured relative to said barrel and body, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said va]ve seat, means cooperating with sa;d barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclos-ing said s,pring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem, spring, retainer, barrel and seat being axially insertable into said body as a unitary assembly in the absence of said removable cover~ aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means communicating with said spring chamber so that relatively rapid flow through said aspirator means causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
In the drawings:
Figure 1 is a side elevation showing a preferred embodiment of this invention.
Figure 2 is a sectional elevation showing a portion of Figure 1.
Figure 3 is a perspective view showing the valve poppet employed in the upstream check valve assembly.
Figure 4 is a transverse sectional view of the valve poppet shown in Pigure 3, taken substantially on the lines 4-4 as shown in Figure 2.
Figure 5 is a sectional elevation of the relief valve assembly.
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Figure 6 is an encl view of the relief valve asse:mbly taken substantially on the lines 6-6 as shown in F;gure 5.
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3~3 ~ eferring to the drawings, the backflow prevention device generally designated 10 is posi.tioned between two Gonventional gate valves ll and 12. The ~ate valve ll forms a part of a water supply pipe, and the gate valve 12 forms a part of a water discharge pipe. The device 10 prevents flow of water from the discharge pipe bac~ into the supply pipe.
As shown in Figure 2, the device 10 includes an upstream check valve assembly generallv designated 13, a downstream check valve assembly generally designated 14 having a zone 15 between them. ~ relief ~alve assembly -generally designated 16 vents ~he zone 15 to atmosphere whenever the pressure in zone 15 and chamber 53 approaches the pressure in the inlet passage 17, within predetermined limits. The passages 17 and 18 and the zone 15 are all formed within the integral body 19. The upstream check valve assembly 13 and the downstream check valve assembly 14 are mounted on the body l9 at right angles to each other, and each is positioned at an angle of 45 degrees to the aligned axes of the inlet and outlet passages 17 and 18.
The upstream check valve assembly 13 includes a sta tionary barrel 21 mounted within the body 19 and having a flange 33 clamped between the body 19 and the station-- ary cover 23. An alignment pin 20 assures the proper orientation of the barrel 2I within the body l9, One end of the barrel 21 has a circular opening 24 defined within a stationary annular seat 25. The barreI 21 has a side window 26 communicating with the zone 15.
A valve poppet 28 is slidably mounted in the barrel :
21 for movement toward and away from the stationary seat , , , .~ .
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L3~33 25. The valve poppet 28 is provided with an annular resilient disk 29 which cooperates with the sea~ 25 to form a bubble tight seal. A re~ainer plate 31 holds the resilient disk in position and is itself fixed to the valve poppet 28 by means of the screw 32. A coil compression spring 33 has one end seated against the internal shoulder 34 of the valve poppet 28 and the other end engaging an end flange 35 on the spring re-tainer 36. The spring 33 encircles the tapering portion 36a of the retainer. A key 37 presents turning of the retainer within the cover 23, which cover is secured to the body 13 by means of threaded fastenings 38, as shown in Figure l. A central non-circular tubular stem 39 is secured to the valve poppet 28 by means of the threaded element 41 and washer 42, and slides through a notching non-circular opening 43 in the radial portion 36b of the spring retainer 36. The stem 39 is received into a matching recess 40 in the valve poppet 28. The valve poppet 28, stem 39, element 41, washar 42, retainer 36 and spring 33 constitute a unitary assembly for installa- -tion into position, in the absence of the cover 23. For safety reasons a special tool is required to engage the threaded element 41. The assembly of cover 23 causes the spring to be further compressed beyond its relaxed positiont An ejector nozzle 44 is mounted OIl the valve poppet 28 and has a relatively large entrance opening 45 commun-icating with the space 46 defined between the valve poppet 28 and the barrel 21 and between the ribs 47 and 48. The r ' ' ' . : ' 3~ ~
discharge opening 49 is smaller and is directed toward a transverse passage 51 in the valve poppet 28 but ~.
which is separated therefrom by the space 52. ~ The space 52 communicates with a reduced pressure chamber 53 con- :
taining the spring 33. This chamber 53 extends into the upper portion of the barrel 21 and into the cover 23 both inside and outside of the spring retainer 36.
A circumferential~ groove 54 is formed in the outer cylindrical surface of the valve poppet 28, and this groove 54 is interrupted at two locations to communicate with the arcuate spaces 55 and 56 formed in the outer surface of the valve poppet 28 and bounded by the inter-: ior surface 57 of the stationary barrel ~l. The arcuate space 55 extends from the rib 48 to the rib 5~, and the arcuate space 56 extends from the rib 47 to the rib 59.
Both of these arcuate spaces 55 and 56 communicate with the window opening 26 in the barrel 21. As best shown in Figure 4~ the transverse passage 51 in the valve poppet ~; 28 discharges through the center of the window opening - 20 26 in:the stationary barrel 21.
The downstream check valve assembly 14 i5 similar to the upstream check valve assembly 13 in many respects except that it does not have an ejector nozzle 44 or a transverse passage 51. The stationary barrel 61 carries the stationary annular seat 62 which is engaged by the resilient disk 63 carried on the valve poppet 64. The coil compression spring 65 engages the cover 66 at one end and engages the valve poppet 64 at the other end.
The cover 66 and the barrel 61 are secured to the body and aligned in the manner described in connection with ~ the upstream chec~ valve assembly 13.
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13~3 The relief valve assembly 16 is best shown in Figures 5 and 6 and it includes a stationary housing 67 and a ~alve member 68 in the housing movable toward and away from a stationary annular seat 69. The 5 resilient disk 71 i.s carried on the valve member for contact with the annular seat 69. The valve member 68 includes a valve stem 72 slidably mounted in the guide 73 and haviny the circular plate 74 ixed on one end by means of the threaded stem element 75 and washer 75a.
The cover 76 is bolted to the housing 67 and clamps the rim of a relatively large rolling diaphxagm 77 between them. The relatively small rolling diaphragm 78 has its outer periphery clamped between the guide 73 and a wall of the housing 67. The inner portion of the rolling diaphragm 78 is fixed to the valve member 68 by means of the clamping plate 79 and threaded ~astenings 81.
The effect of the diaphragm 78 is to offset the unbalanced forces resulting from the pressure differential between zone 15 and atmospheric pressuxe in discharge 104. A
chamber 82 is formed within the housing 67 and between the flexible diaphragms 77 and 78, and this chamber 82 communicates with a terminal fitting 83. A similar ter-minal fitting 84 is carried on the cover 76 and commun-icates with the chamber 85 between the cover 76 and the flexible diaphragm 77.
The coil compression spring has one end seated on the stationary guide member 73 and the other end contacts the pressure plate 87 mounted for self-aligning movement on the spherical surface of the central box 88 on the plate 74. The tubular flanged part 89 is bolted to the housing 67 and 91 and is bolted to the mating flanged part 92 on the body 92 on the body 19, as shown in Figure 1.
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From this description it will be understood that pressure in the cha~ber 85 acts to close the valve disk 71 against the stationary seat 69, in opposition to the force of the spring 86. Pressure in the chamber 82 serves to supplement the force of the spring 86. Movement of the valve member 68 is guided by the sliding contact between the stem 72 and the guide 73 and by the sliding of the fingers 93 in the axial bore 94 of the member having the stationary seat 69. The guide fingers 93 are formed integrally with the circular plate 95 which holds the resilient disk 7]. in place on the valve member 68.
Means are provlded for subjecting the relief valve chamber 85 to pressure in the inlet passage 17 and, as shown in the drawings, this means includes the velocity ;~ 15 sensitive pressure pickup tube 96 extending through the body 19 and connected to the terminal itting 97. A pipe 98 connects the terminal fitting 97 to the terminal itting 84 of the relief valve assembly 16. Additional means are : provided for connectiny the chamber 53 in the upstream check valve assembly 13 to the space 82 in the relief valve housing 67 between the flexible diaphragms 77 and 78. As -; shown in the drawings, this means includes the terminal :-~ fitting 99 which communicates with the chamber 53, and ` the terminal fitting 83 which communicates with the relief valve space 82. A pipe 101 connects the terminal fitting 99 to the temminal fitting 83, as shown in Figure 1. Con-ventional test fittings 102 and 103 are provided on the :~ ~ body 19 in communication with the inlet passage 17 and the outlet passage 18. These test fittings are normally closed.
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3~3 In the operation of the backflow prevention device, the pressume of water in the upstream gate valve 11 acts through the inlet passage 17 and against the exposed portion of the upstream check valve assembly 13 within the annular stationary seat 25. This pressure tends to open the valve in opposition to the force of the spring 33. When the upstream pressure has .reached a su~ficient intensity to move the valve disk 29 away from the seat 25, the pressure acts over a larger cross-sectional area of the valve poppet 28 and the additional force increases the opening movement of the valve disk 29 away from the stationary seat 25. Water flows into the arcuate space 46 between the shoulders 47 and 48 and passes through the ejector nozzle 44 and into the flared entrance opening 50 of the transverse passage 51. The rapid ~low from ~: the small discharge end of the ejector nozzle 44 reduces the pressure of liquid in the chamber 53 by an aspiration efect. Water is discharged from the transverse;passage ~ 51 through the zone~l5 and its velocity head~acts directly :~ 20 on the exposed surface of the valve poppet 64 in the:
downstream check valve assembly 14. Water is discharged .~ through the window 60 in the wall of the barrel 61 and : passes into the discharge passage 18 in the body 19.
The conEiguration of the ribs and spaces on the outer surface o~ the valve poppet 28 i~ the upstream check valve assembly 13 has the following beneficial effect: the flow .:
from the inlet passage 17 is shielded from any substantial .
communication directly with the zone 15, and instead the :.
:~ flow from the inlet passage 17 is directed toward the arcuate space 46 which is defined between the inclined ribs 47 and 48 and which space 46 feeds the ejector nozzle :., . . , :
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44. The spaces or pockets 55 and 56 on the other side of these barrel-containing ribs 47 and 48 are in direct open communication with the side window 26 in the stationary barrel 21, and hence are in communication with the zone 15. The circumferential cross flow on the periphery of the valve poppet 28 through the groove 54, pockets 55 and 56 and side window 26 serves as a barrier to leakage from the inlet 17 axially along the cylindrical surface of the valve poppet 28 into the aspirated chamber 53.
Check valve 13 is designed to maintain a specified minimum pressure dlfferential and cooperates with the relief valve assembly 16 to insure that no reverse flow could ever occur. If for any reason the pressure differ-ential reflected to the assembly falls below a prescribedlevel, the relief valve assembly will open and vent the ` zone 15 to atmosphere as a means of maintaining this required differential. The second check valve 14 normally will also maintain a lesser pressure diffexential; how-ever, it is subject to system presssure conditions wherein -~ the pressure in discharge chamber 18 can exceed the normal ~; supply pressure in chamber 17. Under these conditions the ; function of check valve 14 is to remain closed and isolate zone 15 from the higher backflow pressures. If the second check valve 14 should leak, this reverse flow would tend to equalize the pressure differential maintained across the first check valve 13 and consequently the relief valve assembly 16 would be caused to open and vent the zone 15 to atmosphere and dissipate the reverse flow lea~age.
More particularly, if the differential pressure be-tween the chamber 85 and the chamber 82 is not maintained, '' :
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a3~3 the spring 86 acts in a direction to open the valve by moving the disk 71 away from the stationary seat 69.
Thls pressure differential could be reduced by reason of leakage through the downstream check valve 14, or it might be reduced by failure to maintain the pressure drop through the upstream check valve 13. Any factor or foreign ma~ter which could cause leakage through the upstream check valve 13 would tend to diminish the pressure differential between the chambers 82 and 85.
Check valve 13 functions to maintain a high initial pressure differential as a backflow protection margin of safety, and to resist initial flow through the check valve.
However, as normal flow is established and increases, the initial pressure differential across its seat is re-flected against the larger area of -the valve poppet 28 and is applied across the ejector 44 which in turn aspir- ~:
ates the chamber 53. This combined efect causes the check valve 13 to provide a substantially reduced pressure :~ differential under flowing conditions. This:substantially 20 reduced pressure differential is actually less than the :
initial pressure differential required under a no flow condition. In order to prevent this lower than normal j:
pressure differential from causing the differential relief valve to open, a higher pressure differential is reflected to the relief valve assembly 16 as a result of adding the velocity head pressure sensed through tube 96 to pressure :
chamber 85 and by also applying the reduced pressure in the aspirated chamber 53 to pressure chamber 82. The result is that the differential reflected to the control is greater than the differential between pressure chamber .
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L3~3 17 and zone 15 but it is only greater under velocity flowing conditions. Under static or reverse flow con-ditions wherein the relief valve assembly may be reqwired to open, unwanted pressure differentials related to S normal flow conditions are not induced.
The device shown in the drawings and described above has been found to have exceptional operating char-acteristics. The pressure required for initial opening of the upstream check valve 13 is relatively high, and yet the pressure drop from the inlet passage 17 to the outlet passage 18 is exceptionally low during normal flow conditions.
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~,i co~lxially of said valve seat, a va.:lv~ poppet guided :Eor movement in said barrel toward and al~ay from sa;d va:lve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream chec~ valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seatl an ejector no~le on said valve poppet receiving fluid from said barrel when said valve poppe~ has separated from said valve seat, said ejector nozzle having a discharge end communicating with said chamber so that relatively rapid fluid flow from said ejector causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
~ccording to a ifth aspect of the invention there is provided in backflo~ prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermlned pressure conditions in the pipes, the ilnp~ovement comprisi.ng, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly -3a-... ~ :, :: , : . . .. , ':
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3~3 wilen said valve poppet is initi.ally moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, the downstream check valve assembly having a valve poppet communicating with the zone and positioned to receive the velocity head d;scharge from the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
According to a sixth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstr0am check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pres!sure conditions in the pipes, the improvement comprising, in combination: an inlet pass-age from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved a.way from said seat by fluid pressure D -3b-, .
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ln said in:Let passage, means cooperating with said barrel and said valve poppet to defiTIe a chamber remote from said valve seat, an ejector noz~le on said valve poppet receivîng fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet cooperating with said barrel to form two series of pockets and ribs symmetrical with respect to said ejector nozzle and acting to minimize flow from said seat into said chamber, said ejector nozzle having a discharge end communicating wlth said cllamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said :
1~ chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
According to a seventh aspect of the invention there is provided in a backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assembl:ies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, i.n combination: an inlet passage .
rom-the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly~ a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat~ a spring acting to move said valve poppet into sealing contact wlth said valve seat~ said sprlng actlng to create a pressure drop through the upstream check valve assembbly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector no~zle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve -3c-D
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poppct cooperating with saicl ~arrel to form pockets and ribs to produce circumferential flow o-E fluid on -tlle outer surEace of said valve poppet away from said ejector ~ozzle and thereby acting to minimize axial flow from said seat along said valve poppet into said chamber, said ejector nozzle having a discllarge end communicating with said chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
According toan eighth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downst~eam check valve assemblies wïth a zone between them, and a relie:E valve device for venting the zone to atmosphere under precletermined pressure conditions in the pipes, the ïmprovement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned within the body coaxially of said valve seat, a body having a removable cover, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, saicl valve poppet, stem, spring and retainer being axially insertable into said barrel as a unitary assembly in the absence of said cover, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said -3d-,' ' ' ' .
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va.lve seat, said ejector nozzle having a discharge end communicating with said spring chamber so tilat relatively rapid fluid flow from said ejector nozz:lc causc~s cl re~d~ction in f.luid press~lre in said spring chamber to oppose the action oE said sprïng and thereby reduce the pressure drop across the upstream check valve assem~ly.
According to a ninth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies w;~h a zone between ~hem~ and a relief valve device for venting the zone to atmosphere under prede~ermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the wpstream check valve assembly, a valve poppet guicled for movement toward and away from said valve seat, a first spring acting to move said valve poppet into sealing contact with saicl valve seat, said first spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage~ means cooperating with said valve poppet to define a chamber remote from said valve seat, aspirator means on said valve poppet receiving fluid when said valve poppet has separated from said valve seat, ancl acting to cause a reduction in Eluid pressure in said chamber to oppose the action of said first spring and thereby reduce the pressure dxop across ~he upstream clleck valve assembly, sai.d relief valve device having relatively movable valve parts for controlling flow from said zone to atmosphere, a second spring acting to cause relative movement of said valve parts toward open position, and di:Eferen- :
tial pressure mecms sensitive to pressure in said inlet passage and in said aspira~ed chamber for changing the effective force of said second D -3e-i. . .. . , ., ~ . , . . :
spring.
According to ~q tenth aspect o~ the invention there is provided backflow prevention apparatus for installation between a supply pipe and a discharge pipe, having in combination: a check valve assembly having an inlet passage from the supply pipe terminating in a stationary valve seat, a stationa.ry barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel ~oward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the check valve assembly when said valve poppet is initially moved away from sai.d seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formed be~ween said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stàtionary barrelJ the third chamber being formed downstream of said valve poppet and said barrel~ an ejector nozzle having an intake receiving flow from the first chamber when said valve poppet has separated from said valve seat, a discharge passage from said ejector nozzle communicating with said third chamber, and a space between its intake and its discharge passage connected to said second chamber so that relatively rapid flow from said ejector nozzle causes a reduction :in :Fluid pressure in sn:i.d seconcl chnmbcr to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
Accord:ing to an eleventh aspect of the invention there is provided a pressure differential valve assembly for installation between a supply pipe and a discharge pipe, comprising in combination: an inlet passage from the supply pipe terminati.ng in a stationary valve seat forming a D
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3~3 part of the valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided :for movelllent in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seatj said spring acting to create a pressure drop through the valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber ~eing formed between said valve seat and one side of said valve poppet, the second chamber being formed : .:
on the other side of said valve poppet and in cooperation wlth sa.id stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, aspirator means receiving fluid from said first chamber when said valve poppet has separated from said valve seat, said aspirator means havIng a discharge passàge communicating with said third chamber, said aspirator means being connected to said second chamber so that relatively rapid flow from said aspirator means causes a reduction in fluid pressure in said second chamber to oppose the action :; :
of said spring and thereby reduce the pressure drop across the valve assembly.
According to a twelfth aspect of the inventlon there is provided in backflow prevention apparatus or installat.ion between n supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure condit:ions in the pipes, the :Lmprovement comprising, in combination: an inlet passage from the supply pi.pe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for -3g-~ .
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movement in said barrel -toward and away Erom said valve seat, a spring acting to move said valve ~poppet into seali:ng contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure ïn said ïnlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first :
chamber being formed between said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, aspirator means receiving fluid from said :Eirst chamber when said valve poppet has separated from said valve seat, said aspirator means acting to reduce the pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said second chamber.
According to a thirteenth aspect of the invention there is provided in backflow prevention apparatus for ins~allation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assembli.es with a zone between them, and a relie:E valve device ~or venting the zone to atmosphere ~mder predeterm:ined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part o~ the upstream check valve assembly, a stationary barrel ~`
positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move saïd valve poppet into sealing contact with said valve seat, said -3h-;
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3~3 spring acting to create a pressure drop through the upstream check valve assembly ~ en sai(Z valve poppet is ;nit;ally moved away Erom said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formcd between said valve seat and one side of said valve poppet, :
the second chamber being formed on the other side of said -valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, an ejector nozzle having an intake receiving flow from the first chamber when said valve poppet is separated from said valve seat, a discharge passage rom said ejector nozzle communicating with said third chamber, and a space between its intake and its dîscharge passage connected to said second chamber so that relatively rapid flow from said ejector nozzle causes the reduction in pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
According to a fourteenth aspect of the invention there is provided in backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including a differential check valve ~-assembly for connection to the supply pipe, the improvement comprising, .
in combination: a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet having pockets and ribs cooperating with said barrel to produce circumferential Elow of fluid on the outer -3i-D ~ -~13~1 s~lrface of saicl vaLve poppe-t away from said ejector noz~le and thereby acting to minimize axial flo~ from sai.d valve seat along said valve poppet into said chamber, said ejector nozzle llaving a portion communicat-ing ~ith said cha~,ber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring.
According to a fifteenth aspect of the invention there is provided in a check valve assembly, the improvement comprising, in combination: a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a removable cover secured relative to said barrel, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into seal-ing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem, spring and retainer being axially `~
insertable into said ~arrel as a unitary assembly in the absence of said removable cover, aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means communicat.ing with said spring chamber so that relatively rapid fluid flow through said aspirator means causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
According to a sixteenth aspect of the invention there is provided in a check valve assembly, the improvement comprlsing, in combination: a stationary body, a stationary barrel positioned within -3j-.
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the ~ody and having a coaxial valve seat thereonJ a removable cover secured relative to said barrel and body, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said va]ve seat, means cooperating with sa;d barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclos-ing said s,pring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem, spring, retainer, barrel and seat being axially insertable into said body as a unitary assembly in the absence of said removable cover~ aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means communicating with said spring chamber so that relatively rapid flow through said aspirator means causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
In the drawings:
Figure 1 is a side elevation showing a preferred embodiment of this invention.
Figure 2 is a sectional elevation showing a portion of Figure 1.
Figure 3 is a perspective view showing the valve poppet employed in the upstream check valve assembly.
Figure 4 is a transverse sectional view of the valve poppet shown in Pigure 3, taken substantially on the lines 4-4 as shown in Figure 2.
Figure 5 is a sectional elevation of the relief valve assembly.
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Figure 6 is an encl view of the relief valve asse:mbly taken substantially on the lines 6-6 as shown in F;gure 5.
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3~3 ~ eferring to the drawings, the backflow prevention device generally designated 10 is posi.tioned between two Gonventional gate valves ll and 12. The ~ate valve ll forms a part of a water supply pipe, and the gate valve 12 forms a part of a water discharge pipe. The device 10 prevents flow of water from the discharge pipe bac~ into the supply pipe.
As shown in Figure 2, the device 10 includes an upstream check valve assembly generallv designated 13, a downstream check valve assembly generally designated 14 having a zone 15 between them. ~ relief ~alve assembly -generally designated 16 vents ~he zone 15 to atmosphere whenever the pressure in zone 15 and chamber 53 approaches the pressure in the inlet passage 17, within predetermined limits. The passages 17 and 18 and the zone 15 are all formed within the integral body 19. The upstream check valve assembly 13 and the downstream check valve assembly 14 are mounted on the body l9 at right angles to each other, and each is positioned at an angle of 45 degrees to the aligned axes of the inlet and outlet passages 17 and 18.
The upstream check valve assembly 13 includes a sta tionary barrel 21 mounted within the body 19 and having a flange 33 clamped between the body 19 and the station-- ary cover 23. An alignment pin 20 assures the proper orientation of the barrel 2I within the body l9, One end of the barrel 21 has a circular opening 24 defined within a stationary annular seat 25. The barreI 21 has a side window 26 communicating with the zone 15.
A valve poppet 28 is slidably mounted in the barrel :
21 for movement toward and away from the stationary seat , , , .~ .
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L3~33 25. The valve poppet 28 is provided with an annular resilient disk 29 which cooperates with the sea~ 25 to form a bubble tight seal. A re~ainer plate 31 holds the resilient disk in position and is itself fixed to the valve poppet 28 by means of the screw 32. A coil compression spring 33 has one end seated against the internal shoulder 34 of the valve poppet 28 and the other end engaging an end flange 35 on the spring re-tainer 36. The spring 33 encircles the tapering portion 36a of the retainer. A key 37 presents turning of the retainer within the cover 23, which cover is secured to the body 13 by means of threaded fastenings 38, as shown in Figure l. A central non-circular tubular stem 39 is secured to the valve poppet 28 by means of the threaded element 41 and washer 42, and slides through a notching non-circular opening 43 in the radial portion 36b of the spring retainer 36. The stem 39 is received into a matching recess 40 in the valve poppet 28. The valve poppet 28, stem 39, element 41, washar 42, retainer 36 and spring 33 constitute a unitary assembly for installa- -tion into position, in the absence of the cover 23. For safety reasons a special tool is required to engage the threaded element 41. The assembly of cover 23 causes the spring to be further compressed beyond its relaxed positiont An ejector nozzle 44 is mounted OIl the valve poppet 28 and has a relatively large entrance opening 45 commun-icating with the space 46 defined between the valve poppet 28 and the barrel 21 and between the ribs 47 and 48. The r ' ' ' . : ' 3~ ~
discharge opening 49 is smaller and is directed toward a transverse passage 51 in the valve poppet 28 but ~.
which is separated therefrom by the space 52. ~ The space 52 communicates with a reduced pressure chamber 53 con- :
taining the spring 33. This chamber 53 extends into the upper portion of the barrel 21 and into the cover 23 both inside and outside of the spring retainer 36.
A circumferential~ groove 54 is formed in the outer cylindrical surface of the valve poppet 28, and this groove 54 is interrupted at two locations to communicate with the arcuate spaces 55 and 56 formed in the outer surface of the valve poppet 28 and bounded by the inter-: ior surface 57 of the stationary barrel ~l. The arcuate space 55 extends from the rib 48 to the rib 5~, and the arcuate space 56 extends from the rib 47 to the rib 59.
Both of these arcuate spaces 55 and 56 communicate with the window opening 26 in the barrel 21. As best shown in Figure 4~ the transverse passage 51 in the valve poppet ~; 28 discharges through the center of the window opening - 20 26 in:the stationary barrel 21.
The downstream check valve assembly 14 i5 similar to the upstream check valve assembly 13 in many respects except that it does not have an ejector nozzle 44 or a transverse passage 51. The stationary barrel 61 carries the stationary annular seat 62 which is engaged by the resilient disk 63 carried on the valve poppet 64. The coil compression spring 65 engages the cover 66 at one end and engages the valve poppet 64 at the other end.
The cover 66 and the barrel 61 are secured to the body and aligned in the manner described in connection with ~ the upstream chec~ valve assembly 13.
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13~3 The relief valve assembly 16 is best shown in Figures 5 and 6 and it includes a stationary housing 67 and a ~alve member 68 in the housing movable toward and away from a stationary annular seat 69. The 5 resilient disk 71 i.s carried on the valve member for contact with the annular seat 69. The valve member 68 includes a valve stem 72 slidably mounted in the guide 73 and haviny the circular plate 74 ixed on one end by means of the threaded stem element 75 and washer 75a.
The cover 76 is bolted to the housing 67 and clamps the rim of a relatively large rolling diaphxagm 77 between them. The relatively small rolling diaphragm 78 has its outer periphery clamped between the guide 73 and a wall of the housing 67. The inner portion of the rolling diaphragm 78 is fixed to the valve member 68 by means of the clamping plate 79 and threaded ~astenings 81.
The effect of the diaphragm 78 is to offset the unbalanced forces resulting from the pressure differential between zone 15 and atmospheric pressuxe in discharge 104. A
chamber 82 is formed within the housing 67 and between the flexible diaphragms 77 and 78, and this chamber 82 communicates with a terminal fitting 83. A similar ter-minal fitting 84 is carried on the cover 76 and commun-icates with the chamber 85 between the cover 76 and the flexible diaphragm 77.
The coil compression spring has one end seated on the stationary guide member 73 and the other end contacts the pressure plate 87 mounted for self-aligning movement on the spherical surface of the central box 88 on the plate 74. The tubular flanged part 89 is bolted to the housing 67 and 91 and is bolted to the mating flanged part 92 on the body 92 on the body 19, as shown in Figure 1.
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From this description it will be understood that pressure in the cha~ber 85 acts to close the valve disk 71 against the stationary seat 69, in opposition to the force of the spring 86. Pressure in the chamber 82 serves to supplement the force of the spring 86. Movement of the valve member 68 is guided by the sliding contact between the stem 72 and the guide 73 and by the sliding of the fingers 93 in the axial bore 94 of the member having the stationary seat 69. The guide fingers 93 are formed integrally with the circular plate 95 which holds the resilient disk 7]. in place on the valve member 68.
Means are provlded for subjecting the relief valve chamber 85 to pressure in the inlet passage 17 and, as shown in the drawings, this means includes the velocity ;~ 15 sensitive pressure pickup tube 96 extending through the body 19 and connected to the terminal itting 97. A pipe 98 connects the terminal fitting 97 to the terminal itting 84 of the relief valve assembly 16. Additional means are : provided for connectiny the chamber 53 in the upstream check valve assembly 13 to the space 82 in the relief valve housing 67 between the flexible diaphragms 77 and 78. As -; shown in the drawings, this means includes the terminal :-~ fitting 99 which communicates with the chamber 53, and ` the terminal fitting 83 which communicates with the relief valve space 82. A pipe 101 connects the terminal fitting 99 to the temminal fitting 83, as shown in Figure 1. Con-ventional test fittings 102 and 103 are provided on the :~ ~ body 19 in communication with the inlet passage 17 and the outlet passage 18. These test fittings are normally closed.
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3~3 In the operation of the backflow prevention device, the pressume of water in the upstream gate valve 11 acts through the inlet passage 17 and against the exposed portion of the upstream check valve assembly 13 within the annular stationary seat 25. This pressure tends to open the valve in opposition to the force of the spring 33. When the upstream pressure has .reached a su~ficient intensity to move the valve disk 29 away from the seat 25, the pressure acts over a larger cross-sectional area of the valve poppet 28 and the additional force increases the opening movement of the valve disk 29 away from the stationary seat 25. Water flows into the arcuate space 46 between the shoulders 47 and 48 and passes through the ejector nozzle 44 and into the flared entrance opening 50 of the transverse passage 51. The rapid ~low from ~: the small discharge end of the ejector nozzle 44 reduces the pressure of liquid in the chamber 53 by an aspiration efect. Water is discharged from the transverse;passage ~ 51 through the zone~l5 and its velocity head~acts directly :~ 20 on the exposed surface of the valve poppet 64 in the:
downstream check valve assembly 14. Water is discharged .~ through the window 60 in the wall of the barrel 61 and : passes into the discharge passage 18 in the body 19.
The conEiguration of the ribs and spaces on the outer surface o~ the valve poppet 28 i~ the upstream check valve assembly 13 has the following beneficial effect: the flow .:
from the inlet passage 17 is shielded from any substantial .
communication directly with the zone 15, and instead the :.
:~ flow from the inlet passage 17 is directed toward the arcuate space 46 which is defined between the inclined ribs 47 and 48 and which space 46 feeds the ejector nozzle :., . . , :
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44. The spaces or pockets 55 and 56 on the other side of these barrel-containing ribs 47 and 48 are in direct open communication with the side window 26 in the stationary barrel 21, and hence are in communication with the zone 15. The circumferential cross flow on the periphery of the valve poppet 28 through the groove 54, pockets 55 and 56 and side window 26 serves as a barrier to leakage from the inlet 17 axially along the cylindrical surface of the valve poppet 28 into the aspirated chamber 53.
Check valve 13 is designed to maintain a specified minimum pressure dlfferential and cooperates with the relief valve assembly 16 to insure that no reverse flow could ever occur. If for any reason the pressure differ-ential reflected to the assembly falls below a prescribedlevel, the relief valve assembly will open and vent the ` zone 15 to atmosphere as a means of maintaining this required differential. The second check valve 14 normally will also maintain a lesser pressure diffexential; how-ever, it is subject to system presssure conditions wherein -~ the pressure in discharge chamber 18 can exceed the normal ~; supply pressure in chamber 17. Under these conditions the ; function of check valve 14 is to remain closed and isolate zone 15 from the higher backflow pressures. If the second check valve 14 should leak, this reverse flow would tend to equalize the pressure differential maintained across the first check valve 13 and consequently the relief valve assembly 16 would be caused to open and vent the zone 15 to atmosphere and dissipate the reverse flow lea~age.
More particularly, if the differential pressure be-tween the chamber 85 and the chamber 82 is not maintained, '' :
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a3~3 the spring 86 acts in a direction to open the valve by moving the disk 71 away from the stationary seat 69.
Thls pressure differential could be reduced by reason of leakage through the downstream check valve 14, or it might be reduced by failure to maintain the pressure drop through the upstream check valve 13. Any factor or foreign ma~ter which could cause leakage through the upstream check valve 13 would tend to diminish the pressure differential between the chambers 82 and 85.
Check valve 13 functions to maintain a high initial pressure differential as a backflow protection margin of safety, and to resist initial flow through the check valve.
However, as normal flow is established and increases, the initial pressure differential across its seat is re-flected against the larger area of -the valve poppet 28 and is applied across the ejector 44 which in turn aspir- ~:
ates the chamber 53. This combined efect causes the check valve 13 to provide a substantially reduced pressure :~ differential under flowing conditions. This:substantially 20 reduced pressure differential is actually less than the :
initial pressure differential required under a no flow condition. In order to prevent this lower than normal j:
pressure differential from causing the differential relief valve to open, a higher pressure differential is reflected to the relief valve assembly 16 as a result of adding the velocity head pressure sensed through tube 96 to pressure :
chamber 85 and by also applying the reduced pressure in the aspirated chamber 53 to pressure chamber 82. The result is that the differential reflected to the control is greater than the differential between pressure chamber .
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L3~3 17 and zone 15 but it is only greater under velocity flowing conditions. Under static or reverse flow con-ditions wherein the relief valve assembly may be reqwired to open, unwanted pressure differentials related to S normal flow conditions are not induced.
The device shown in the drawings and described above has been found to have exceptional operating char-acteristics. The pressure required for initial opening of the upstream check valve 13 is relatively high, and yet the pressure drop from the inlet passage 17 to the outlet passage 18 is exceptionally low during normal flow conditions.
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Claims (23)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, the downstream check valve assembly having a valve poppet communicating with the zone and positioned to receive the velocity head discharge from the upstream check valve assembly.
2. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle causes a re-duction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
3. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating m a stationary annular valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means acting to reduce the pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve sub-jected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
4. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary annular valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said chamber so that relatively rapid fluid flow from said ejector causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
5. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, the downstream check valve assembly having a valve poppet communicating with the zone and positioned to receive the velocity head discharge from the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said chamber of the upstream check valve assembly.
6. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet cooperating with said barrel to form two series of pockets and ribs symmetrical with respect to said ejector nozzle and acting to minimize flow from said seat into said chamber, said ejector nozzle having a discharge end communicating with said chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
7. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from -the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet cooperating with said barrel to form pockets and ribs to produce circumferential flow of fluid on the outer surface of said valve poppet away form said ejector nozzle and thereby acting to minimize axial flow from said seat along said valve poppet into said chamber, said ejector nozzle having a discharge end communicating with said chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
8. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned within the body coaxially of said valve seat, a body having a removable cover, a valve poppet guided for movement in said barrel toward and away from said valve seat, a apring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem, spring and retainer being axially insertable into said barrel as a unitary assembly in the absence of said cover, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, said ejector nozzle having a discharge end communicating with said spring chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly.
9. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a valve poppet guided for movement toward and away from said valve seat, a first spring acting to move said valve poppet into sealing contact with said valve seat, said first spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said valve poppet to define a chamber remote from said valve seat, aspirator means on said valve poppet receiving fluid when said valve poppet has separated from said valve seat, and acting to cause a reduction in fluid pressure in said chamber to oppose the action of said first spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having relatively movable valve parts for controlling flow from said zone to atmosphere, a second spring acting to cause relative movement of said valve parts toward open position, and differential pressure means sensitive to pressure in said inlet passage and in said aspirated chamber for changing the effective force of said second spring.
10. The combination set forth in claim 9 in which said relief valve device has a first expansible space sensitive to pressure in said inlet passage and has a second expansible space sensitive to pressure in said aspirated chamber, said spaces sharing a common movable wall.
11. The combination of any one of claims 1, 2 or 3 wherein said relief valve device includes a maovable valve element cooperating with a stationary seat for controlling flow to atmosphere from said zone, a second spring acting to cause said movable valve element to move toward open position, and differential pressure means sensitive to pressure in said inlet passage and in said chamber for changing the effective force of said second spring.
12. The combination of any one of claims 1, 2 or 3 wherein said relief valve device includes a movable valve element cooperating with a stationary seat for controlling flow from said zone to atmosphere, said movable valve element including a stem, a body enclosing said stem and having a cover, a plate having a spherical hub portion fixed to said stem, a first flexible diaphragm engaging said plate and having an outer peri-phery clamped between the cover and the body to form a first expansible space, a second flexible diaphragm extending between the stem and the body, a self-aligned member mounted on said spherical hub portion of said plate, a spring operatively positioned between said member and said body and acting to move said movable valve element away from said stationary seat, means for connecting the space within the body and between said diaphragms to said aspirated chamber.
13. The combination of any one of claims 1, 2 or 3 wherein said relief valve device includes a movable valve element cooperating with a stationary seat for controlling flow from said zone to atmosphere, said movable valve element including a stem, a body enclosing said stem and having a cover, a first flexible diaphragm having an outer periphery clamped between the cover and the body to form a first expansible space, a second flexible diaphragm extending between the stem and the body, a spring operatively positioned between said stem and said body, said means including a guide member within said spring fixed relative to said body and having sliding contact with said stem, said guide means also including fingers carried by said movable valve element and slidably engaging a stationary bore upstream of said stationary seat, means for connecting said first expan-sible space to said inlet passage, and means for connecting the space between said diaphragms to said aspirated chamber.
14. Backflow prevention apparatus for installation between a supply pipe and a discharge pipe, having in combination: a check valve assembly having an inlet passage from the supply pipe terminating in a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber keying formed between said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, an ejector nozzle having an intake receiving flow from the first chamber when said valve poppet has separated from said valve seat, a discharge passage from said ejector nozzle communicating with said third chamber, and a space between its intake and its discharge passage connected to said second chamber so that relatively rapid flow from said ejector nozzle causes a reduction in fluid pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
15. A pressure differential valve assembly for installation between a supply pipe and a discharge pipe, comprising in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formed between said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, aspirator means receiving fluid from said first chamber when said valve poppet has separated from said valve seat, said aspirator means having a discharge passage communicating with said third chamber, said aspirator means being connected to said second chamber so that relatively rapid flow from said aspirator means causes a reduction in fluid pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the valve assembly.
16. The combination set forth in claim 15 in which said aspirator means comprises an ejector nozzle having an intake receiving flow from said first chamber, a discharge passage communicating with said third chamber, and a space between the intake and the discharge passage connected to said second chamber.
17. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formed between said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, aspirator means receiving fluid from said first chamber when said valve poppet has separated from said valve seat, said aspirator means acting to reduce the pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the upstream check valve assembly, said relief valve device having a valve subjected to differential pressure between the pressure in the inlet passage and the pressure in said second chamber.
18. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including upstream and downstream check valve assemblies with a zone between them, and a relief valve device for venting the zone to atmosphere under predetermined pressure conditions in the pipes, the improvement comprising, in combination: an inlet passage from the supply pipe terminating in a stationary valve seat forming a part of the upstream check valve assembly, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, said spring acting to create a pressure drop through the upstream check valve assembly when said valve poppet is initially moved away from said seat by fluid pressure in said inlet passage, means cooperating with said barrel and said valve poppet to define three chambers, the first chamber being formed between said valve seat and one side of said valve poppet, the second chamber being formed on the other side of said valve poppet and in cooperation with said stationary barrel, the third chamber being formed downstream of said valve poppet and said barrel, an ejector nozzle having an intake receiving flow from the first chamber when said valve poppet is separated from said valve seat, a discharge passage from said ejector nozzle communicating with said third chamber, and a space between its intake and its discharge passage connected to said second chamber so that relatively rapid flow from said ejector nozzle causes the reduction in pressure in said second chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
19. The combination set forth in claim 18 in which the downstream check valve assembly has a valve poppet communicating with the third chamber and positioned to receive the velocity head discharge from the upstream check valve assembly.
20. The combination set forth in claim 18 in which said ejector nozzle is mounted on said valve poppet.
21. In backflow prevention apparatus for installation between a supply pipe and a discharge pipe, the apparatus including a differential check valve assembly for connection to the supply pipe, the improvement comprising, in combination: a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said valve poppet to define a chamber remote from said valve seat, an ejector nozzle on said valve poppet receiving fluid from said barrel when said valve poppet has separated from said valve seat, the outer surface of the valve poppet having pockets and ribs cooperating with said barrel to produce circumferential flow of fluid on the outer surface of said valve poppet away from said ejector nozzle and thereby acting to minimize axial flow from said valve seat along said valve poppet into said chamber, said ejector nozzle having a portion communicating with said chamber so that relatively rapid fluid flow from said ejector nozzle causes a reduction in fluid pressure in said chamber to oppose the action of said spring.
22. In a check valve assembly, the improvement comprising, in combina-tion: a stationary valve seat, a stationary barrel positioned coaxially of said valve seat, a removable cover secured relative to said barrel, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem, spring and retainer being axially insertable into said barrel as a unitary assembly in the absence of said removable cover, aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means communicating with said spring chamber so that relatively rapid fluid flow through said aspirator means causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
23. In a check valve assembly, the improvement comprising, in combina-tion: a stationary body, a stationary barrel positioned within the body and having a coaxial valve seat thereon, a removable cover secured relative to said barrel and body, a valve poppet guided for movement in said barrel toward and away from said valve seat, a spring acting to move said valve poppet into sealing contact with said valve seat, means cooperating with said barrel and said cover and said valve poppet to define a spring chamber remote from said valve seat and enclosing said spring, said valve poppet having a central axial stem fixed thereto, a spring retainer positioned within a portion of said spring and having a central opening for sliding contact with said stem, said valve poppet, stem spring, retainer, barrel and seat being axially insertable into said body as a unitary assembly in the absence of said removable cover, aspirator means receiving fluid from said barrel when said valve poppet has separated from said valve seat, said aspirator means communicating with said spring chamber so that relatively rapid flow through said aspirator means causes a reduction in fluid pressure in said spring chamber to oppose the action of said spring and thereby reduce the pressure drop across the check valve assembly.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US91864678A | 1978-06-23 | 1978-06-23 | |
| US918,646 | 1978-06-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1101303A true CA1101303A (en) | 1981-05-19 |
Family
ID=25440726
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA330,412A Expired CA1101303A (en) | 1978-06-23 | 1979-06-22 | Backflow prevention apparatus |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS5527576A (en) |
| CA (1) | CA1101303A (en) |
| DE (1) | DE2925179A1 (en) |
| GB (5) | GB2102918B (en) |
| MX (1) | MX150564A (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5896644A (en) * | 1981-12-03 | 1983-06-08 | Mitsubishi Rayon Co Ltd | Reinforced resin composition |
| JPS58125724A (en) * | 1982-01-21 | 1983-07-26 | Asahi Chem Ind Co Ltd | Resin foam |
| ATE15822T1 (en) * | 1982-01-26 | 1985-10-15 | Socla | BACKFLOW PREVENT FOR PRESSURE LINES. |
| JPS59102947A (en) * | 1982-12-02 | 1984-06-14 | Mitsubishi Rayon Co Ltd | Methacrylic resin composition |
| JPS59152855A (en) * | 1983-02-22 | 1984-08-31 | 旭化成株式会社 | Solid multilayer acryl sheet-shaped shape |
| JPS6086150A (en) * | 1983-10-18 | 1985-05-15 | Mitsubishi Rayon Co Ltd | Thermoplastic resin composition having excellent heat resistance and impact resistance |
| GB2179121B (en) * | 1985-08-17 | 1989-08-02 | Wigley Albert F | Improvements in or relating to fluid control valves |
| JPH02153962A (en) * | 1988-07-04 | 1990-06-13 | Asahi Chem Ind Co Ltd | Thermoplastic acrylic resin composition |
| JP2593557B2 (en) * | 1989-07-20 | 1997-03-26 | 旭化成工業株式会社 | Multi-layer acrylic polymer |
| US4991622A (en) * | 1989-12-19 | 1991-02-12 | Cmb Industries | Multiply configurable backflow preventer |
| DE29605420U1 (en) * | 1996-03-23 | 1996-06-13 | Festo Kg, 73734 Esslingen | Quick exhaust valve for pneumatic applications |
| WO2002021029A1 (en) * | 2000-09-07 | 2002-03-14 | Cmb Industries, Inc. | Short-length reduced-pressure backflow preventor |
| CN1950412B (en) | 2004-03-30 | 2010-11-10 | 三菱丽阳株式会社 | Impact resistance modifier and resin composition |
| JP5401030B2 (en) | 2007-11-27 | 2014-01-29 | 住友化学株式会社 | Extruded resin film and method for producing the same |
| JP5123654B2 (en) | 2007-12-11 | 2013-01-23 | 住友化学株式会社 | Method for producing extruded resin plate |
| JP5323349B2 (en) | 2007-12-21 | 2013-10-23 | 住友化学株式会社 | Method for producing extruded resin sheet |
| JP5189399B2 (en) | 2008-04-07 | 2013-04-24 | 国立大学法人信州大学 | Check valve |
| JP5189403B2 (en) * | 2008-05-08 | 2013-04-24 | 国立大学法人信州大学 | Backflow prevention device |
| JP5323546B2 (en) * | 2009-03-23 | 2013-10-23 | 住友化学株式会社 | Matte resin film, decorative film, decorative sheet and decorative molded product using the same |
| EP2711394A4 (en) | 2011-05-10 | 2014-04-02 | Mitsubishi Rayon Co | Acrylic resin composition, acrylic resin sheet, acrylic resin laminate, and manufacturing method for same |
| USD736870S1 (en) * | 2013-06-07 | 2015-08-18 | The Pill Golf LLC | Flat chamfered golf ball |
| TWI633147B (en) | 2013-11-25 | 2018-08-21 | Kuraray Co., Ltd. | Acrylic resin film and manufacturing method thereof |
| JP7145150B2 (en) | 2017-05-16 | 2022-09-30 | 株式会社カネカ | DOPE FOR FILM MANUFACTURING AND METHOD FOR MANUFACTURING FILM |
| CN108717963B (en) * | 2018-06-01 | 2024-06-18 | 宁德时代新能源科技股份有限公司 | Valve assembly, cover assembly, secondary battery and battery module |
| CN111692771B (en) * | 2019-03-15 | 2023-12-19 | 开利公司 | Ejector and refrigeration system |
| CN113803503B (en) * | 2021-09-17 | 2023-04-18 | 沈阳工程学院 | Right-angle hydraulic control one-way valve for internet of things terminal information acquisition |
-
1979
- 1979-06-21 MX MX17816779A patent/MX150564A/en unknown
- 1979-06-22 GB GB8132471A patent/GB2102918B/en not_active Expired
- 1979-06-22 DE DE19792925179 patent/DE2925179A1/en not_active Withdrawn
- 1979-06-22 GB GB8216022A patent/GB2101716B/en not_active Expired
- 1979-06-22 CA CA330,412A patent/CA1101303A/en not_active Expired
- 1979-06-22 GB GB7921914A patent/GB2023776B/en not_active Expired
- 1979-06-22 JP JP7900779A patent/JPS5527576A/en active Pending
-
1981
- 1981-10-28 GB GB8132470A patent/GB2108241B/en not_active Expired
-
1982
- 1982-06-02 GB GB8216023A patent/GB2104195B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2101716A (en) | 1983-01-19 |
| GB2104195A (en) | 1983-03-02 |
| GB2023776A (en) | 1980-01-03 |
| GB2023776B (en) | 1983-02-16 |
| JPS5527576A (en) | 1980-02-27 |
| GB2102918B (en) | 1983-06-08 |
| DE2925179A1 (en) | 1980-01-24 |
| MX150564A (en) | 1984-05-30 |
| GB2101716B (en) | 1983-05-25 |
| GB2108241A (en) | 1983-05-11 |
| GB2108241B (en) | 1983-09-07 |
| GB2102918A (en) | 1983-02-09 |
| GB2104195B (en) | 1983-06-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |