US3779268A

US3779268A - Automatic changeover valve for chlorine gas system

Info

Publication number: US3779268A
Application number: US00262385A
Authority: US
Inventors: W Conkling
Original assignee: Pennwalt Corp
Current assignee: US Filter Wallace and Tiernan Inc
Priority date: 1972-06-13
Filing date: 1972-06-13
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18
Also published as: AU465232B2; CA965329A; AU5299273A

Abstract

An automatic changeover diaphragm valve for chlorine gas service incorporates a loading spring on the atmospheric side of the diaphragm in order to provide a regulated positive pressure discharge. A latching mechanism for the valve employs spaced parallel rods which engage a V-groove on the loading spring spool to hold the valve in standby condition prior to release for changeover operation. The diaphragm includes a tetrafluorethylene web on the gas side and a chlorosulfonated web on the atmospheric side clamped at the outer peripheries. A sectored metal disk is used to abut against the chlorosulfonated web while the central portions of the two webs are in clamped disposition.

Description

United States Patent [191 Conkling 1 AUTOMATIC CHANGEOVER VALVE FOR CHLORINE GAS SYSTEM [21] Appl. No.: 262,385

US. Cl 137/113, 137/510, 222/6 Int. Cl. GOSd 7/01 Field of Search 137/113,114,118,

References Cited UNITED STATES PATENTS 10/1956 Zimmer et al. 137/113 12/1965 Kilbourn 137/510 FOREIGN PATENTS OR APPLICATIONS 1,126,436 Germany 137/1 [3 670,224 1/1939 Germany 251/297 Primary ExaminerAlan Cohan Assistant Examiner-Edward Look Attorney-Stanley Bilker et a1,

[57] ABSTRACT An automatic changeover diaphragm valve for chlorine gas service incorporates a loading spring on the atmospheric side of the diaphragm in order to provide a regulated positive pressure discharge. A latching mechanism for the valve employs spaced parallel rods which engage a V-groove on the loading spring spool to hold the valve in standby condition prior to release for changeover operation. The diaphragm includes a tetrafluorethylene web on the gas side and a chlorosulfonated web on the atmospheric side clamped at the outer peripheries. A sectored metal disk is used to abut against the chlorosulfonated web while the central portions of the two webs are in clamped disposition.

, AUTOMATIC CHANGEOVER VALVE FOR CHLORINE GAS SYSTEM This invention relates to diaphragm valves, and more particularly relates to diaphragm valves of the automatic changeover type which are employed in corrosive gas or liquid systems, such as in dispensing chlorine. The present invention constitutes an improvement over the automatic changeover valve shown and described in prior US. Pat. No. 3,604,445.

Chlorine, because of its exceedingly high chemical activity coupled with the facility with which it diffuses readily through non-rigid materials, has previously presented almost insurmountable difficulties for the diaphragm. While thin sheets of a noble metal, such as silver or tantalum, enjoy a degree of success in corrosive environments, the fatigue created by repeated deflections over extended periods of time causes them to rupture andresults in a most serious problem of chlorine'leakage. In a compact automatic changeover valve which requires considerable diaphragm excursion in order to latch, metal diaphragms are entirely impractical.

Halocarbon polymers, such as chlorinated and fluorinated ethylenes and propylenes in the form of semirigid plastic sheets or elastomers, alone or in combination with chlorosulfonated elastomers have also been tried for diaphragm service, but 'without significant success. In such instances, the chlorine permeated entirely through thin sections at a very high rate, and even though the diaphragm was under negative pressure, there was severe corrosive attack upon metallic parts on the atmospheric side. Elastomers reinforced with glass or polyester cloth by lamination separated in a short time with consequent disintegration. While unreinforced elastomers not only lacked the necessary strength without the back-up means, but also ultimately distorted as a result of swelling with consequent malfunction of the valve itself. When layers of the foregoing materials had been used the osmotic pressures tended to build up between the layers causing distortion and rupture in the direction of the chlorine system.

Another significant aspect of the present invention is derived from the fact that the majority of water and waste treatment chlorination systems operate under a positive pressure at the supply end where a changeover valve is most useful. Accordingly, a basic improvement of the instant automatic changeover valve is in the provision of means permitting the diaphragm to operate against a positive pressure discharge, i.e., a pressure greater than atmospheric, in contradistinction to the sub-atmospheric or vacuum discharge of the automatic changeover valve shown and claimed in US. Pat. No. 3,604,455. The means for affording such a positively pressured output is accomplished by way of a spring biasing force which is disposed to opening the valve against a balancing regulated working pressure in the opposite direction on the clamped diaphragm. A still further improvement provided by the valve herein to be described is in the use of a relatively strong and compact detent mechanism vis-avis the magnetic or toggle latch of the aforesaid patented system which retains the valve in standby position.

It is therefore an object of this invention to provide an automatic changeover valve for positive pressure discharge.

Another object of this invention is to provide an automatic changeover valve for use with corrosive fluids and gases.

Yet another object of this invention is to provide an improved standby latching device for automatic changeover valves.

A still further object of this invention is to provide a diaphragm construction for regulating and changeover valves used in a corrosive fluid environment wherein repeated deflections at relatively high excursions will be withstood without rupture or leakage.

Other objects of this invention are to provide an improved device of the character described that is easily and economically produced, sturdy in construction including subsidiary operating, maintenance and servicing advantages, and both highly efficient and effective in operation.

With the above and related objects in view, this in vention consists of the details of construction and combination of parts as will be more fully understood from the following detailed description when read in conjunction with the accompanying drawing in which:

FIG. 1 is a fragmentary elevational view of a gas dispenser system using an automatic changeover valve embodied in this invention.

FIG. 2 is a sectional view taken longitudinally through one of the valves.

FIG. 3 is an exploded perspective view of a diaphragm assembly employed in the automatic changeover valve.

FIG. 4 is a sectional view taken along lines 44 of FIG. 2.

FIG. 5 is a sectional view taken along lines 5-5 of FIG. 2.

Referring now in greater detail to the drawings in which similar reference characters refer to similar parts, there is shown a pair of automatic changeover valves V1 and V2, each comprising a housing, generally designated as A, a diaphragm, generally designated as B, a valve member, generally designated as C, and a latching assembly D for holding the valve unit in standby position. As has been set forth in considerable detail in prior US. Pat. No. 3,604,455, the automatic changeover valves are used in pairs and are coupled to respective gas cylinder E1 and E2. The pressure responsive diaphragm B allows each of the valve units V1 and V2 to be modulated between closed and open positions, the latching mechanism D functioning to hold one valve in a standby closed position while the other valve is open and dispensing chlorine into the system from its associated cylinder. Depletion of the chlorine in the first cylinder E1 causes a decrease in system pressure by way of a control unit F connected to the two valve units by

separate conduits

10 and 12. The control unit F is connected by conduit 16 to a suitable injector (not shown) in order to dispense the chlorine at a controlled rate. In this invention, the control unit F requires a supply pressure above atmospheric to function normally. Depletion of the chlorine in the first cylinder E1 causes a decrease in system pressure which when communicated to the second valve V2 releases the diaphragm of the latter from its detent latch whereupon the second valve unit is opened to initiate discharge of chlorine from the second cylinder E2 when the first is exhausted.

The housing A of each valve comprises a body portion 18, a collector portion 20 and a cap 22, all preferably of metallic construction. The collector portion 20 is of generally cylindrical configuration and is attached to the body portion 18 in gas tight disposition therewith by a plurality of screws 24 extending through circumferentially spaced openings in collector flange 26 and threadably engaging respective tapped holes in the body 18. A gasket 28 inserted within a complementary groove in one surface of the body portion 18 is engaged in sealing disposition by a shoulder 30 projecting from the collector flange 26. The cap 22 is secured to the opposite face ofthe body portion 18 by a series of screws 32 threadably engaging circumferentially spaced tapped holes in the body portion after passing through respective holes in the diaphragm B as well as the cap itself so as to clamp the margins of the diaphragm therebtween. The body portion includes an inlet port 36 and an outlet port 38 diametrically disposed therein with respect to each other and being threaded to receive complementary fittings. In the present design, inlet port 36 is closed off with a threaded plug 40, and an alternate threaded inlet 36A is provided in the collector 20 to permit filtering of impurities in the chlorine supplies. That is, impurities in the chlorine supplies have a tendency to deposit within the area of the valve member C, and, when such deposits accumulate to an appreciable extent, there is a likelihood in certain installations for the valve stem to jam in open position. As is apparent, a valve fixed in open disposition could result in an uncontrolled chlorine flow together with possible hazardous venting of the chlorine from the chlorinator system itself.

As is shown in FIG. 2, a filter assembly Cl is used to strain out the majority of the fine residual in the chlorine which does not settle out within the collector 20. A cylindrical filter cap 42 having an opening 44 at one end thereof covered by a filter 46 of felt composition is utilized to screen out the impurities. Flange 48 on the filter cap 42 is drawn into abutting engagement upon an annular extension 50 of the body portion 18 with a gasket 52 therebetween by nut 56, the latter threadedly engaging a complementary threaded portion 58 on the exterior of annular extension 50. The inlet 36A is at the bottom of the collector 20 so that any condensate in the chamber thereof can drain back toward the supply. In the event that the quality of the chlorine supply and the rate of flow do not warrant the filter assembly Cl, a gas cap 42A with a closed end wall may be used in substitution of filter cap 42. In the latter case the plug 40 is removed from the inlet port 36 so that the body port 36 may be coupled to a gas supply E instead of the collectors inlet port 36A. The collector portions 20, the holding screws 24, and the gasket 28 may then be entirely omitted in order to simplify the device and reduce cost.

The valve assembly C includes a molded tetrafluorethylene seat portion 60, which is a force fit within a shouldered bore 62 of the body 18, and a valve stem 64 longitudinally slidable with respect thereto. The conical forward end 66 of the valve stem is adapted to engage upon and close off a counterbored orifice extending through the seat 60.

The valve stem 64 includes a guide rod having a forward extension 70 which is carried loosely within the orifice 68 and a rearward extension 72 which is carried within a guide retainer 74. The guide retainer 74 is of U-shaped configuration and includes a washer spotwelded thereto which is held against the felt'filter 46 and the end wall of the filter cap 42 (or closed cap 42A) by compression spring 76. The spring'76 is of coil or helical disposition the forward end of which is reduced in diameter for abutment against a shoulder 68. The spring 76 has a working force of approximately 8 pounds and biases the stem 64 into closed disposition against the seat 60 such that the forward extension projects beyond the peripheral edge of the hub 80 integrally formed on body portion 18.

The diaphragm B constitutes a non-adhesively secured stack comprising a tetrafluorethylene sheet 82 on the chlorine gas side in abutment with a chlorosulfonated polyethylene (Hypalon) sheet 84 on the atmospheric side. The sheet 82 may be 0.010 inch thick skived electrical grade Teflon, while 0.031 inch thick sheet I-Iypalon or Viton (fluorelastomer) have proven satisfactory for the laminate 84. A partially segmented washer 86 with radially extending slots 88 abuts the elastomeric sheet 84. The washer or sector plate 86 is of 1/64 inch beryllium copper sheet and acts as a barrier against blowout of the unclamped area of the diaphragm. The central portions of the

laminates

82 and 84 as well as the sector plate 86 are drawn into clamped disposition by a flat headed screw 90 threadedly engaging a tapped bore 92 in spool piece 94. The spool piece 94 is of Monel metal and includes an enlarged head 96 for abutting up against the interior margin of the sector plate 86. The head 96 of the spool piece has a peripheral V-groove 98 which constitutes a detent for the latch mechanism D, while the marginal edges of the

sheets

82 and 84 of the diaphragm B are clamped between the cap 22 and the body portion 18. It is to be observed that the outer and inner margins of the sector plate 86 remain unclamped. Thus, the respective outer and inner margins of the sector plate may float freely within an internal recess 100 in the cap 22 and a recess at the end of the spool piece 94.

The sector plate 86 thus acts to insure against blowout should inadvertent overpressure occur within the valve body 18 but does not impede extension of the diaphragm over the range of deflections required. The chlorine initially diffuses through the tetrafluorethylene sheet 82 and into contact with the elastomeric (I-Iypalon or Viton) diaphragm 84 causing the latter to become tacky. The pressure of the gas against the proximal side of the diaphragm causes the now tacky I-Iypaion or Viton sheet 84 to bond to the face of the washer 86 in a relatively short time. Once the diaphragm 84 is bonded to the sector washer plate 86, the chlorine gas can no longer flow between the surfaces of the elastomeric diaphragm 84 and the segments of the washer 86 itself. Thus, after bonding of the sectored plate 86 and the segments thereof to the diaphragm web 84, the only areas through which chlorine may thereafter diffuse are the radially extending slots 88. In the present design, the slots 88 occupy less than 5 percent of the total area of the washer, the metal itself being impermeable. While the elastomeric web 84 may be prebonded to the washer plate 86, it could be redundant in view of the short period of time that it takes for chlorine to diffuse through the tetrafluorethylene web 82 and activate the elastomeric web 84. Protection of the elastomeric diaphragm 84 from direct contact with the chlorine is accomplished by means of the tetrafluorethylene web 82 between the gas and elastomer. The osmotic pressure for tetrafluorethylene is so low that it does not separate from the elastomer. The elastomer promotes a gas tight sea] at the clamped edges and the center of the diaphragm stack. Blowout protection is provided by the strength of the beryllium copper washer 86 and the tetrafluorethylene web 82. At the same time excellent flexibility and resistance to fatigue are provided by the elastomeric web 84 and the segments of the sectored beryllium copper washer 86.

The latch mechanism D includes an apertured circular plate 102 having parallel beryllium

copper wire rods

104 and 106 spaced from each other by a distance slightly less than the periphery of the spool head 96. The

rods

104 and 106 are set within spaced grooves in the detent plate 102 and are loosely held therein when the plate is affixed to the interior of the body 18 by screws 108. The aperture 110 of the detent plate 102 is sufficiently large to permit the head 96 of the spool 94 to pass therethrough after the detent latch has been released. When the spool 94 is drawn to the left as shown in FIGS. 2 and 3, the

rods

104 and 106 engage within the V-groove 98 so as to retain the diaphragm B in latched standby position until the latching or detent force is exceeded. Coil spring 112 compressed between the end wall 114 of cap 22 and the head 96 of the spool 94 is resisted in part by the pressure on the diaphragm B effected by the other control valve as well as by the detent force.

In order to latch the diaphragm B against the force of the spring 112, a knob 116 having internal threads 118 engaging complementary external threads on the cap 22 is rotated counterclockwise. Accordingly, a screw 126 having its shank threaded within a tapped bore 122 in the spool 94 and its head retained within a counterbore 124 in the knob 116 is caused to be drawn to the left until the V-groove detent 98 is engaged by the

detent rods

104 and 106. Once the detent is latched, the knob 116 is rotated in the opposite direction to its inoperative position whereby the detent force and the pressure under the diaphragm B regulated by the alternate valve unit V2 hold the detent in latched disposition against the force of the main spring 112. The spring 112 which has a working load of typically 50 pounds tends to open the valve C against a balanced regulated pressure of 25 psi. acting on the clamped diaphragm B, typically square inches in effective area. The detent force of the latching mechanism D is norinally 30 pounds retention force.

When the alternate supply cylinder E2 is depleted and the regulated pressure effected by control unit F falls below its normal level, for example, 10 p.s.i., the force under the diaphragm B of standby valve V1 becomes insufficient to hold the detent latch D. The force of the main spring 112 thereupon dislodges the grooved head of spool 94 from the detent pins 104 and 106 so as to snap the diaphragm into its operative or regulating position and effect gas flow changeover from cylinder D2 to cylinder D1. Note that in operative position the head of screw 90 abuts up against the stem extension rod 70 to open the valve C against the force of biasing spring 76 in a manner substantially as set forth in US. Pat. No. 3,604,445 except for the fact the instant changeover valve system operates against a positive pressure discharge and uses a spring 112 on the atmospheric side whereas the prior patented system operated against a negative or vacuum pressure. Because of the net inward force on the diaphragm of the foregoing patented construction, there was no need to include a spring or equivalent thereof on the atmospheric side of the diaphragm.

During actual operation of the changeover valves in a chlorination system, it is possible that chlorine may be withdrawn from the cylinders E at such high rates that the pressure diminishes to the actuation of changeover level before the first cylinder is empty. For example, 5 to 10 pounds of liquid chlorine may remain in a 150 pound cylinder at the time of changeover when a withdrawal rate of pounds per day is maintained. Ambient heat is not transferred through the walls of the cylinder so as to maintain a minimum of IO p.s.i. gas pressure when the level of liquid chlorine in the cylinder is low but not completely exhausted.

In the present invention, washers are incorporated behind the spool head 94 under the main spring 112 so as to adjust the regulated pressure upwardly to a very precise level. The two valves V1 and V2 can thereby be adjusted to provide the same regulated pressure within a very small tolerance, for example, 26 1% p.s.i. With such a balance, the two valves V1 and V2 in an operating system will tend to pass chlorine after the reserve valve has switched open, thus permitting the nearly empty container to exhaust itself within a reasonable time in contradistinction to a valve on an exhausted cylinder which tended to regulate at an appreciably lower level than the alternate valve.

Of especial usefulness is the ability to accomplish positive shut off of the valve at any time, as when it is desired to service the chlorinator, by backing off the threaded knob 116. As is apparent, when the knob 116 is in off position (fully counterclockwise), the biasing spring 76 acts to close the orifice 68 by forcing the stem 64 against the valve seat 60 regardless of the pressure downstream of the orifice 68.

Although this invention has been described in considerable detail, such description is intended as being illustrative rather than limiting, since the invention may be variously embodied without departing from the spirit thereof and the scope of the invention is to be determined as claimed.

What is claimed is:

1. In a system for supplying gaseous material from cylinders containing the gaseous material at elevated pressure, a pair of combined changeover and selfregulating valve units respectively adapted to be connected to a pair of said cylinders for successively deliv ering from one cylinder at a time a flow of the gaseous material to a common location at a reduced constant positive pressure, each valve unit comprising:

a valve body including a chamber therein and means for coupling said body to one of said cylinders,

a displaceable valve member for opening and closing the corresponding valve unit,

a pressure sensitive diaphragm defining one side of the chamber in the valve body, and displacing said valve member in response to variations in pressure at the common downstream location between a closed position at which gaseous supply is cut off to an open disposition in which the valve unit is open for controlled discharge of said gaseous material at a reduced substantially constant positive pressure,

resilient means biasing said diaphragm toward the chamber and acting to open the valve against a balanced regulated positive pressure of a predetermined level, and

latching means cooperating with and acting against the force of said resilient means when set to retain said diaphragm in an inoperative standby position at which the valve member is closed until the downstream pressure falls below a predetermined abnormal positive level, said latch means being unlatched when the downstream pressure falls below the predetermined abnormal positive level so that the gaseous material will be delivered from one cylinder in the system at a time until depletion thereof whereupon automatic changeover to a fresh cylinder will occur for delivery at the same predetermined constant level until all cylinders are exhausted.

2. The valve unit of claim 1 wherein the latching means comprises a cylindrical member coupled to said diaphragm and having a circumferential V-groove peripherally formed therein, and a pair of spaced parallel rods mounted within said valve body and adapted to engage within said V-groove to define a detent therewith when said cylindrical member is drawn longitudinally a predetermined distance away from said chamber against the force of said resilient means and the internal resistance of said diaphragm.

3. The valve unit of claim 2 wherein said resilient means comprises a coil spring.

4. The valve unit of claim 3 including a cylindrical cap over said diaphragm on the side thereof opposite to the body chamber.

5. The valve unit of claim 4 wherein said cap is externally threaded and a knob having internal threads complementary and in engagement with the external threads of the cap, and means coupling said knob with said cylindrical member whereby turning the knob in one direction will latch the detent and then rotating the knob in the opposite direction will set the diaphragm in standby position.

6. The valve unit of claim 5 including means to adjust the force exerted by the springs in each valve unit so that the pair of valve units are balanced.

7. The valve unit of claim 1 wherein said diaphragm comprises a tetrafluorethylene web and a chlorosulfonated polyethylene elastomeric web, said webs being clamped in stacked disposition at the periphery thereof so that the tetrafluorethylene web is in direct contact with the gaseous material, a circular washer having radially extending slots therein in abutment with the chlo rosulfonated diaphragm, and means to clamp the center areas of said two webs and said washer together.

. sums mmw omcs CERWFEATE @F QCGRREC'NON Patent No- 3, 779, 268 iisw Ianuary 14, 1974 Inventor) Wiliiam C. Conkling It is cm ntzu'riwfa than smm? soy-sass in tho abova-idmtiiie patent and that said Lastaa s $652632: item's sows-mas as bslow:

Column 1, line 56, 3, 604, 455 should read also Column 2, line 43, 3, 604, 455 should read -3, 604, 445;

Signed and sealed this is: day of October 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR C. DANN Commissioner of Patents Attesting Officer

Claims

2. The valve unit of claim 1 wherein the latching means comprises a cylindrical member coupled to said diaphragm and having a circumferential V-groove peripherally formed therein, and a pair of spaced parallel rods mounted within said valve body and adapted to engage within said V-groove to define a detent therewith when said cylindrical member is drawn longitudinally a predetermined distance away from said chamber against the force of said resilient means and the internal resistance of said diaphragm.
3. The valve unit of claim 2 wherein said resilient means comprises a coil spring.
4. The valve unit of claim 3 including a cylindrical cap over said diaphragm on the side thereof opposite to the body chamber.
5. The valve unit of claim 4 wherein said cap is externally threaded and a knob having internal threads complementary and in engagement with the external threads of the cap, and means coupling said knob with said cylindrical member whereby turning the knob in one direction will latch the detent and then rotating the knob in the opposite direction will set the diaphragm in standby position.
6. The valve unit of claim 5 including means to adjust the force exerted by the springs in each valve unit so that the pair of valve units are balanced.
7. The valve unit of claim 1 wherein said diaphragm comprises a tetrafluorethylene web and a chlorosulfonated polyethylene elastomeric web, said webs being clamped in stacked disposition at the periphery thereof so that the tetrafluorethylene web is in direct contact with the gaseous material, a circular washer having radially extending slots therein in abutment with the chlorosulfonated diaphragm, and means to clamp the center areas of said two webs and said washer together.