US3852547A - Differential pressure switch with hinged plate on diaphragm - Google Patents

Differential pressure switch with hinged plate on diaphragm Download PDF

Info

Publication number
US3852547A
US3852547A US00391052A US39105273A US3852547A US 3852547 A US3852547 A US 3852547A US 00391052 A US00391052 A US 00391052A US 39105273 A US39105273 A US 39105273A US 3852547 A US3852547 A US 3852547A
Authority
US
United States
Prior art keywords
diaphragm
pressure
differential pressure
switch
contact
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 - Lifetime
Application number
US00391052A
Inventor
H Dietz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US00391052A priority Critical patent/US3852547A/en
Application granted granted Critical
Publication of US3852547A publication Critical patent/US3852547A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00Switches operated by change of a physical condition
    • H01H35/24Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/26Details
    • H01H35/2607Means for adjustment of "ON" or "OFF" operating pressure
    • H01H35/2614Means for adjustment of "ON" or "OFF" operating pressure by varying the bias on the pressure sensitive element
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00Switches operated by change of a physical condition
    • H01H35/24Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/34Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm
    • H01H35/346Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by diaphragm in which the movable contact is formed or directly supported by the diaphragm

Definitions

  • FIG. 3 is a section view taken along section line 3-3 DIFFERENTIAL PRESSURE SWITCH WITH HINGED PLATE ON DIAPHRAGM BACKGROUND OF THE INVENTION
  • This invention relates generally to electrical switches and more particularly to an electrical differential pressure switch.
  • Differential pressure switches are known. Generally these switches are somewhat expensive to construct since they must be sealed to provide a positive seal on the vacuum side thereof and require leverage systems for rendering them sensitive. They are not able to take large overloads without damage and are substantially limited as to range of operation so that if a wide range of response to pressures is desired there is a decided limitation as to this range. Furthermore, the switches are generally circular in configuration and they require special complex tooling for the manufacture thereof.
  • Another object of the present invention isto provide an electrical differential pressure switch of a configuration which makes it possible to construct various sizes of the switch for different applications without great tooling costs.
  • Another object of the present invention is to provide a switch which is readily sealed eliminating the use of friction-creating seals.
  • FIG. 2 is a se'ction view taken along section line2 2
  • FIG. 1 is a front elevation view of a switch accordingofFlG. 2; I
  • FIG. 4 is a fragmentary section -view of a modification of the switch in FIGSYI and 3 and illustrates a flowswitchembodiment; and i I FIG. 5 is a section view taken along section line 5-,-5.
  • the diaphragm pressure plate 21a is constructed with lesser surface area than the cloth diaphragm 20 and has an edge 23 bearing on an edge surface 24 of the frame 21 so that it is pivotal thereon so that the two opposed edges 23, 24 define a hinge or pivot for pivoting of the backing or pressure plate 210.
  • the assembled diaphragm and backing plate define a vacuum space 26 and a pressure space 27 within a housing 10, 12 of the electrical differential pressure switch according to the invention.
  • a bracket 29 is mounted on the front plate 10 and supports thereon a micro switch having an electrical contact 31 bearing against a flexible flat clock spring 33 mounted on the bracket by a threaded fastener 34 and its nut 34a.
  • a floating pin 36 provided with a head 36a, of larger diameter. than the shank of the pin, is axially movable in a bearing 40 mounted on the bracket 29.
  • the pin 36 extends through the bearing into the vacuum space 26.
  • a seal 42 seals the base of the bearing and opening in the front plate through which the pin 36 passes and forms a seal circumferentially of'the floating pin and .provided on the backside of the switch and is in communication'with theinterior of the pressure space 27. Both compartments are fluidtight.
  • a vacuum is supplied to the space 26and fluid pressure is supplied to the pressure space 27.
  • the differential pressure willactuate the floating pin which bears on the flat clock spring 33 which will flex and actuate the" micro switch contact.
  • the differential pressure switch can be actuated by air flow, a liquid level of pressure, alevel-of granulematerials or pressure from an inflated bladder subjected to externalpressure and is excellent for use with fluidic circuits. 1
  • the vacuum connector When used as a differential pressureswitch it can be ures the, total pressure and the vacuum connector is connected to an opening in an airduct perpendicular to the air flow (static pressure). It can accordingly be used 'to indicate staticpressu're and it can alsoindicate a vacuum.
  • the switch construction according to the invention allows increasing the 'size of the switches conings 18. Between the front andback' plates is mounted structed and increasing the area of the diaphragm so that the sensitivity of the switch can be increased. A sensitivity of 0.02 inches of water column pressurehas been obtained. Likewise, by decreasing the area of the diaphragm the switch can be used at high pressures, in
  • the flat spring can be removed and changed and accordingly a different pressure response can be set on the switch by changing the flat spring.
  • FIGS. 4 and Sin which the diaphragm 21a is provided with an eyeleted'hole 22.
  • This embodiment makes the switch a flow switch.
  • the fluid media which could include water or some other liquid, passing th'rougli the pressure connection into the inner chamber of the switch would pass through the eyeleted hole and out thevacuum connection of the switch.
  • the pressure in the pressure chamber would be higher than the pressure in-the vacuum chamber. The difference between these two pressures is dependent on the rate of flow of the fluid through the eyeleted hole. This difference in pressure can be established to actuate the micro switch when a specific rate of flow is obtained.
  • said actuating element comprises an adjustingscrew, one of said plates having a sealed opening defining an access to .said adjusting screw, and means sealing said opening.
  • An electrical differentialv pressure switch including means removably mounting said flat spring for interchangementfof flat springs of different strengths therebyto vary the response of said switch to different pressure differentialsu,
  • a differential pressure switch according to claim 1 including a thin flexible seal circumferentially of said contact flexing when the contact is actuated? 7.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Switches Operated By Changes In Physical Conditions (AREA)

Abstract

A pressure-responsive switch responsive to a differential pressure developed internally of a housing having a pressureresponsive diaphragm. The diaphragm supports an actuating element that impinges upon an axially displaceable pin extending outwardly of the housing. The pin bears against a flat spring that is flexed to close an electrical contact in dependence upon the pressure differential. The flat spring is removably mounted for exchange of springs to vary the range of operation of the switch.

Description

United States Patent [1 1 [111 3,852,547
Dietz i Dec. 3, 1974 DIFFERENTIAL PRESSURE SWITCH WITH HINGED PLATE ON DIAPHRAGM [76] Inventor: Henry G. Dietz, 8O Salisburg Ave.,
Garden City, NY. 11530 [22] Filed: Aug. 24, 1973 [21] Appl. No.: 391,052
52 us. Cl. 200/83 Y, 200/83 A [51] Int. Cl. H0111 35/34 [58] Field Of Search ZOO/61.25, 81.9 R, 83 A, 200/83 8,83 N, 83 S, 83 SA, 83 Y, 83 P [56] References Cited UNITED STATES PATENTS 2,500,457 3/1950 Hess u 200/83 A 3,002,064 9/1961 Nelsen 200/83 A 3,005,887 10/1961 Robson 200/83 A 3,256,045 6/1966 $161261 ZOO/81.9 R
3,424,883 1/1969 Heskett ZOO/81.9 R 3,689,719 9/1972 Phillips 200/83 N FOREIGN PATENTS OR APPLICATIONS 676,140 2/l930 France 200/83 N Primary ExaminerRobert K. Schaefer Assistant ExaminerGerald P. Tolin Attorney, Agent, or FirmRobert E. Burns; Emmanuel J. Lobato; Bruce L. Adams [57] ABSTRACT 7 Claims, 5 Drawing Figures of no.1;
FIG. 3 is a section view taken along section line 3-3 DIFFERENTIAL PRESSURE SWITCH WITH HINGED PLATE ON DIAPHRAGM BACKGROUND OF THE INVENTION This invention relates generally to electrical switches and more particularly to an electrical differential pressure switch.
Differential pressure switches are known. Generally these switches are somewhat expensive to construct since they must be sealed to provide a positive seal on the vacuum side thereof and require leverage systems for rendering them sensitive. They are not able to take large overloads without damage and are substantially limited as to range of operation so that if a wide range of response to pressures is desired there is a decided limitation as to this range. Furthermore, the switches are generally circular in configuration and they require special complex tooling for the manufacture thereof.
SUMMARY OF THE INVENTION It is a principal object of the presentinvention to provide a sensitive electrical differential pressure switch which is,
inexpensive to construct and easy to 'vary the sensitivity thereof and which has a very wide range pressure response. It has a minimum of working parts and has the abilityto obtain large leverage ratios. Another object of the present invention isto provide an electrical differential pressure switch of a configuration which makes it possible to construct various sizes of the switch for different applications without great tooling costs. V
Another object of the present invention is to provide a switch which is readily sealed eliminating the use of friction-creating seals. 1
BRIEF DESCRIPTION OF THE-DRAWINGS Other features and advantages of the electrical differential pressure switch in accordance with the present invention will be better'understood as described in the following specificationv and appended claims in conjunction with- -the following drawings in which:
to the invention;
FIG. 2 is a se'ction view taken along section line2 2 FIG. 1 is a front elevation view of a switch accordingofFlG. 2; I
FIG. 4 is a fragmentary section -view of a modification of the switch in FIGSYI and 3 and illustrates a flowswitchembodiment; and i I FIG. 5 is a section view taken along section line 5-,-5.
A v prises a front plate and a back plate 12 spaced from each other by rectangular gaskets 14,15 made of a compressible material, such as cork or the like, and
held together by a plurality of screws 17 within busha diaphragm 20 made of a flexible material; for example cloth suitably impregnated with butyl or silicone, and a diaphragm pressure plate 21a which comprises a tongue of a metallic frame 21. The plate 21a is actually not a part of the frame 2l'and the cloth diaphragm 20 is bonded thereto as illustrated in FIGS. 2 and 3. The diaphragm pressure plate 21a is constructed with lesser surface area than the cloth diaphragm 20 and has an edge 23 bearing on an edge surface 24 of the frame 21 so that it is pivotal thereon so that the two opposed edges 23, 24 define a hinge or pivot for pivoting of the backing or pressure plate 210. The assembled diaphragm and backing plate define a vacuum space 26 and a pressure space 27 within a housing 10, 12 of the electrical differential pressure switch according to the invention.
A bracket 29 is mounted on the front plate 10 and supports thereon a micro switch having an electrical contact 31 bearing against a flexible flat clock spring 33 mounted on the bracket by a threaded fastener 34 and its nut 34a. I
A floating pin 36 provided with a head 36a, of larger diameter. than the shank of the pin, is axially movable in a bearing 40 mounted on the bracket 29. The pin 36 extends through the bearing into the vacuum space 26. A seal 42 seals the base of the bearing and opening in the front plate through which the pin 36 passes and forms a seal circumferentially of'the floating pin and .provided on the backside of the switch and is in communication'with theinterior of the pressure space 27. Both compartments are fluidtight. i
In operation a vacuum is supplied to the space 26and fluid pressure is supplied to the pressure space 27. The differential pressure willactuate the floating pin which bears on the flat clock spring 33 which will flex and actuate the" micro switch contact. The differential pressure switch can be actuated by air flow, a liquid level of pressure, alevel-of granulematerials or pressure from an inflated bladder subjected to externalpressure and is excellent for use with fluidic circuits. 1
When used as a differential pressureswitch it can be ures the, total pressure and the vacuum connector is connected to an opening in an airduct perpendicular to the air flow (static pressure). It can accordingly be used 'to indicate staticpressu're and it can alsoindicate a vacuum.
The switch construction according to the the invention allows increasing the 'size of the switches conings 18. Between the front andback' plates is mounted structed and increasing the area of the diaphragm so that the sensitivity of the switch can be increased. A sensitivity of 0.02 inches of water column pressurehas been obtained. Likewise, by decreasing the area of the diaphragm the switch can be used at high pressures, in
pounds per square inch levels.
The use of a diaphragm with a backing plate construction and the hinge position and direct pin actuation at a pointvery close to the hinge point results in a possibilityof using a small diaphragm to seal the vacuum side of the switch with no friction loss in transmitting the main diaphragm force to the micro switch. This makes the switch totally sealed on the vacuum side and makes use of friction-creating seals unncessary.
Moreover, the flat spring can be removed and changed and accordingly a different pressure response can be set on the switch by changing the flat spring.
.A modification of the switch is shown in FIGS. 4 and Sin which the diaphragm 21a is provided with an eyeleted'hole 22. This embodiment makes the switch a flow switch. The fluid media, which could include water or some other liquid, passing th'rougli the pressure connection into the inner chamber of the switch would pass through the eyeleted hole and out thevacuum connection of the switch. The pressure in the pressure chamber would be higher than the pressure in-the vacuum chamber. The difference between these two pressures is dependent on the rate of flow of the fluid through the eyeleted hole. This difference in pressure can be established to actuate the micro switch when a specific rate of flow is obtained.
What l claim and desire to secure by letters patent is:
fining a hinge for said pressure plate about which the pressure plate pivots, an electrical contact mounted on saidhousing exteriorly of said space, an actuator for'ac:
tuating said contact to an operative position comprising a flexible flat spring mounted exteriorly of said casing for flexing to a position to close said contact, an axially displaceable pin in communication with the interior of said housing and extending outwardly thereof for bearing against said float spring to deflect it in a direction for closing said contact, an actuating element mounted on said diaphragm for movement therewith to contact and engage said pin to actuate it in response to a pressure differential in said compartments flexing the diaphragm in a direction for actuating said switch, and connectors for applying a medium to one of said compartments to develop said differential pressure.
2. An electrical differential pressure switch accord ing to claim 1, in which said diaphragm comprises a rectangular flexible area, said diaphragm pressure plate having a generally rectangular area of lesser dimension than the area of. said flexible'material.
3. An electrical differential pressure switch according to claim 1, in which said actuating element is disposed adjacent said diaphragm pressure'plate edge surface.
4. An electrical differentiaal pressure switch according to claim 3, in which said actuating element comprises an adjustingscrew, one of said plates having a sealed opening defining an access to .said adjusting screw, and means sealing said opening.
5. An electrical differentialv pressure switch according to claim 1, including means removably mounting said flat spring for interchangementfof flat springs of different strengths therebyto vary the response of said switch to different pressure differentialsu,
- 6. A differential pressure switch according to claim 1, including a thin flexible seal circumferentially of said contact flexing when the contact is actuated? 7. A differential pressure switch according to claim whereby said differentialiswitch'functions as'a flow switch actuatable when a specific flow rate obtains -40 through said opening.

Claims (7)

1. A differential pressure switch comprising a housing comprising two spaced, opposed plates defining a fluidtight space therebetween, a flexible pressure responsive diaphragm comprising a flexible material and a diaphragm pressure plate bonded to said flexible material separating said space into two compartments, a rigid member having an edge surface in said space opposed to an edge surface of said pressure plate and in close proximity therewith, the edge surfaces jointly defining a hinge for said pressure plate about which the pressure plate pivots, an electrical contact mounted on said housing exteriorly of said space, an actuator for actuating said contact to an operative position comprising a flexible flat spring mounted exteriorly of said casing for flexing to a position to close said contact, an axially displaceable pin in communication with the interior of said housing and extending outwardly thereof for bearing against said float spring to deflect it in a direction for closing said contact, an actuating element mounted on said diaphragm for movement therewith to contact and engage said pin to actuate it in response to a pressure differential in said compartments flexing the diaphragm in a direction for actuating said switch, and connectors for applying a medium to one of said compartments to develop said differential pressure.
2. An electrical differential pressure switch according to claim 1, in which said diaphragm comprises a rectangular flexible area, said diaphragm pressure plate having a generally rectangular area of lesser dimension than the area of said flexible material.
3. An electrical differential pressure switch according to claim 1, in which said actuating element is disposed adjacent said diaphragm pressure plate edge surface.
4. An electrical differentiaal pressure switch according to claim 3, in which said actuating element comprises an adjusting screw, one of said plates having a sealed opening defining an access to said adjusting screw, and means sealing said opening.
5. An electrical differential pressure switch according to claim 1, including means removably mounting said flat spring for interchangement of flat springs of different strengths thereby to vary the response of said switch to different pressure differentials.
6. A differential pressure switch according to claim 1, including a thin flexible seal circumferentially of said contact flexing when the contact is actuated.
7. A differential pressure switch according to claim 1, in which said diaphragm has an opening providing communication between said two compartments, whereby said differential switch functions as a flow switch actuatable when a specific flow rate obtains through said opening.
US00391052A 1973-08-24 1973-08-24 Differential pressure switch with hinged plate on diaphragm Expired - Lifetime US3852547A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US00391052A US3852547A (en) 1973-08-24 1973-08-24 Differential pressure switch with hinged plate on diaphragm

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00391052A US3852547A (en) 1973-08-24 1973-08-24 Differential pressure switch with hinged plate on diaphragm

Publications (1)

Publication Number Publication Date
US3852547A true US3852547A (en) 1974-12-03

Family

ID=23545015

Family Applications (1)

Application Number Title Priority Date Filing Date
US00391052A Expired - Lifetime US3852547A (en) 1973-08-24 1973-08-24 Differential pressure switch with hinged plate on diaphragm

Country Status (1)

Country Link
US (1) US3852547A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3989910A (en) * 1975-04-07 1976-11-02 Robertshaw Controls Company Control device and method of making the same
US4433219A (en) * 1982-02-22 1984-02-21 Dietz Henry G Differential pressure switch with square diaphragm plate supported by the diaphragm
US4692574A (en) * 1985-06-15 1987-09-08 Honeywell B.V. Differential pressure responsive switch
WO1990000806A1 (en) * 1988-07-11 1990-01-25 Robertshaw Controls Company Control device, electrical switch unit therefor and methods of making the same
US4932120A (en) * 1988-07-11 1990-06-12 Robertshaw Controls Company Method of making a control device and electrical switch unit therefor
US4951810A (en) * 1988-07-11 1990-08-28 Robertshaw Control Company Fluid control device for electrical switch unit
US5122628A (en) * 1990-05-25 1992-06-16 Fike Corporation Sudden pressure rise detector
GB2252673A (en) * 1991-01-28 1992-08-12 Dwyer Instr In field settable differential pressure switch assembly
US6452122B1 (en) * 1999-03-31 2002-09-17 Leroy Peter C. Pressure sensing device
US20110036175A1 (en) * 2009-08-14 2011-02-17 Land Iii H Bruce Apparatus and Method for High Frequency Low Pressure Arc Flash Sensor
US20120199109A1 (en) * 2011-02-07 2012-08-09 Carrier Corporation Method And System For Variable Speed Blower Control

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2500457A (en) * 1946-12-10 1950-03-14 Harry A Dutton Jr Fluid pressure switch
US3002064A (en) * 1958-03-26 1961-09-26 Axel L Nielsen Sump pump and flood control equipment
US3005887A (en) * 1958-04-16 1961-10-24 American Air Filter Co Air flow control apparatus
US3256045A (en) * 1962-06-22 1966-06-14 Kelsey Hayes Co Tractor-trailer brake system
US3424883A (en) * 1965-11-15 1969-01-28 Don E Heskett Fluid conducting device and pressure sensitive control means
US3689719A (en) * 1971-09-13 1972-09-05 Dwyer Instr Fluid pressure operated diaphragm switch with improved adjustment means and contact structure

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2500457A (en) * 1946-12-10 1950-03-14 Harry A Dutton Jr Fluid pressure switch
US3002064A (en) * 1958-03-26 1961-09-26 Axel L Nielsen Sump pump and flood control equipment
US3005887A (en) * 1958-04-16 1961-10-24 American Air Filter Co Air flow control apparatus
US3256045A (en) * 1962-06-22 1966-06-14 Kelsey Hayes Co Tractor-trailer brake system
US3424883A (en) * 1965-11-15 1969-01-28 Don E Heskett Fluid conducting device and pressure sensitive control means
US3689719A (en) * 1971-09-13 1972-09-05 Dwyer Instr Fluid pressure operated diaphragm switch with improved adjustment means and contact structure

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3989910A (en) * 1975-04-07 1976-11-02 Robertshaw Controls Company Control device and method of making the same
US4433219A (en) * 1982-02-22 1984-02-21 Dietz Henry G Differential pressure switch with square diaphragm plate supported by the diaphragm
US4692574A (en) * 1985-06-15 1987-09-08 Honeywell B.V. Differential pressure responsive switch
WO1990000806A1 (en) * 1988-07-11 1990-01-25 Robertshaw Controls Company Control device, electrical switch unit therefor and methods of making the same
US4914264A (en) * 1988-07-11 1990-04-03 Robertshaw Controls Company Control device having a self-supporting switch unit therein
US4932120A (en) * 1988-07-11 1990-06-12 Robertshaw Controls Company Method of making a control device and electrical switch unit therefor
US4951810A (en) * 1988-07-11 1990-08-28 Robertshaw Control Company Fluid control device for electrical switch unit
US5122628A (en) * 1990-05-25 1992-06-16 Fike Corporation Sudden pressure rise detector
GB2252673A (en) * 1991-01-28 1992-08-12 Dwyer Instr In field settable differential pressure switch assembly
GB2252673B (en) * 1991-01-28 1994-11-16 Dwyer Instr In field settable differential pressure switch assembly for fluid pressure applications
US6452122B1 (en) * 1999-03-31 2002-09-17 Leroy Peter C. Pressure sensing device
US20110036175A1 (en) * 2009-08-14 2011-02-17 Land Iii H Bruce Apparatus and Method for High Frequency Low Pressure Arc Flash Sensor
US8091429B2 (en) 2009-08-14 2012-01-10 The Johns Hopkins University Apparatus and method for high frequency low pressure arc flash sensor
US20120199109A1 (en) * 2011-02-07 2012-08-09 Carrier Corporation Method And System For Variable Speed Blower Control
US9200847B2 (en) * 2011-02-07 2015-12-01 Carrier Corporation Method and system for variable speed blower control

Similar Documents

Publication Publication Date Title
US3852547A (en) Differential pressure switch with hinged plate on diaphragm
US4091249A (en) Pressure sensitive electrical switch having a snap element
US3492968A (en) Fluid actuated visual indicator
US4450375A (en) Piezoelectric fluid control device
US3270771A (en) Resilient disc check valve
US4254731A (en) Filter restriction indicator
KR920001585A (en) Push switch with improved operator assembly
JPH07280678A (en) Differential pressure switching device and display device with servo piston guided by returning spring
GB1311143A (en) Fluid spring
SE500280C2 (en) Keyboard
GB1153458A (en) Improvements in or relating to Pressure Responsive Devices
KR930020508A (en) Pressure Differential Switch for Gas Storage Pressure Vessel
US3814877A (en) Pressure switch with diaphragm and adjustable contact
US3187711A (en) Magnetic pressure indicator
US5081328A (en) Flow switch
US4433219A (en) Differential pressure switch with square diaphragm plate supported by the diaphragm
US4101747A (en) Differential pressure operated switch
US3483800A (en) Fluidically operated actuator means or the like
GB925284A (en)
GB1217812A (en) A differential pressure responsive switch
US6596951B1 (en) Snap disc pressure switch
GB2132415A (en) Diaphragm pressure switch
US3349203A (en) Pressure equalizing switch device
GB2129618A (en) Pressure responsive device having an hysteresis characteristic
CA1210333A (en) High gain pneumatic switch