US3870436A

US3870436A - Air release valve for self-priming pumps

Info

Publication number: US3870436A
Application number: US451794A
Authority: US
Inventors: Dennis K Remy
Original assignee: Gorman Rupp Co
Current assignee: Gorman Rupp Co
Priority date: 1974-03-18
Filing date: 1974-03-18
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

An automatic air release valve for connection to the discharge side of a self-priming pump, which valve includes a through flow passage having a maximum angular flow change of about 45*, a reciprocal valving rod actuatable to open and close the flow passage, a spring urging the rod toward its open position, and a flexible diaphragm connected to the rod and forming an expansible chamber in the housing communicating with the valve inlet so that pressure generated in the chamber will cause the diaphragm to move the rod and close the passage.

Description

United States Patent 1 1 Remy [ 1 Mar. 11, 1975 AIR RELEASE VALVE FOR SELF-PRIMING PUMPS [75] Inventor: Dennis K. Remy, Galion, Ohio [73] Assignee: The Gorman-Rupp Company,

Mansfield, Ohio 22 Filed: Mar. 18, 1974 211 Appl. No.: 451,794

[52] U.S. C1 ..417/299,137/505.l3, 137/510 [51} Int. Cl. F04b 49/00, F16k 31/12 158] Field of Search 137/510, 505.13; 417/299; 415/27 [56] References Cited UNITED STATES PATENTS 3,123,094 3/1964 Toschkoff 137/505.13

3,575,521 4/1971 Porter 415/21 3,730,215 5/1973 Conery et al. l37/505.l3 X

3,732,889 5/1973 Conery et a1. 137/498 Primary ExaminerC. J. Husar Assistant ExaminerRichard E. Gluck Attorney, Agent, or FirmWatts, Hoffmann, Fisher & Heinke Co.

[57] ABSTRACT 15 Claims, 7 Drawing Figures AIR RELEASE VALVE FOR SELF-PRIMING PUMPS BACKGROUND OF THE INVENTION The present invention relates generally to the selfpriming pump art, and more specifically to a selfpriming pumping system including a new and improved automatic air release valve connected to the discharge side of the pump for venting air from the system.

The customary pumping arrangement employed in sewage lift stations and the like is comprised of at least one self-priming centrifugal pump, a suction inlet pipe connected to the intake side of the pump, a discharge main connected to the discharge side of the pump, and a one-way check valve in the discharge main which prevents liquid from flowing back to the pump when it is shut down.

When the pump is started up, the air in the pumping chamber and any air in the section inlet pipe must be evacuated in order to achieve a full prime. The air which is evacuated cannot be forced pass the check valve in the discharge main because self-priming pumps have limited air compression capability. For example, a typical four inch self-priming centrifugal pump may develop a maximum pressure of 7 psi at its rated speed. If such a pump is installed in a system with a discharge check valve which requires a pressure in excess of 7 psi to open, the pump will not develop sufficient pressure to open the check valve and initiate flow. It is therefore necessary to provide an air release valve between the check valve and the pump for venting air from the system. In order to have an efficiently operating system, the air release valve should automatically close when the pump is operating at rated capacity and head.

Various types of air release valves, such as those disclosed in US. Pat. Nos. 3,474,735, 3,575,521, 3,730,215, 3,732,889 and 3,741,675, have been proposed in the past for use in systems of the type described. Many of these prior art valves are unstable under certain operating conditions, for example, low pressure conditions, and are prone to hydraulic chattering. Another serious disadvantage of conventional air release valves is that they can be easily plugged or fouled by stones, sticks, stringy material and other solids commonly found in raw sewage and the like.

SUMMARY or THE INVENTION An object of the present invention is to provide a pumping system including a self-priming pump and a new and improved air release valve connected to the discharge side of the pump which is open during the priming cycle to vent the evacuated air and which automatically closes when the pump is fully primed to prevent venting of liquid during the pumping cycle.

Another object of the present invention is to provide a new and improved air release valve for use in a pumping system of the type described which is pressure responsive to assure proper opening and closing of the valving element and which is not subject to hydraulic chattering during use.

A further object of the present invention is to provide a new and improved pressure responsive, air release valve suitable for use in pumping systems handling raw sewage and other liquids which contain solids.

Still another object of the present invention is to provide a new and improved air release valve of the type described which affords a self-flushing action, whereby any debris in the valve will be automatically flushed out when the associated pump is actuated.

In the preferred embodiment of the invention, the new air release valve comprises a housing having a through flow passage which connects inlet and outlet ports, a reciprocal valving rod which is movable to open and close the passage, and a flexible diaphragm which is connected to the rod and forms an expansible chamber in the housing. A spring acts on the rod to urge it toward an open position of the valve.

An important feature of the new valve construction is that it is pressure responsive rather than flow responsive, as is typical of many prior art constructions. In the valve of the present invention, the expanisble chamber on one side of the diaphragm communicates directly withthe inlet port. When the pressure in this expansible chamber increases at the end of the priming cycle of the associated pump, the diaphragm is flexed to move the valving rod to a closed position in which it plugs the flow passage in the housing. The valve is automatically opened by the action of the spring whenthe pressure in the expansible chamber decreases, such as when the pump is shut down and/or when the prime is lost. Because of the pressure responsive design of the new valve construction, it is not subject to hydraulic chattering under low pressure operating conditions.

Another important feature of the present invention is the construction which avoids clogging by the debris contained in raw sewage, etc. In the preferred embodiment of the invention, the flow passage through the housing has a maximum angular flow change, i.e.. maximum deviation from straight line flow, of 45. It is also preferred that the flow passage have a minimum diam eter of one inch. It has been found that a one inch diameter passage having a maximum angular flow change of 45 avoids all plugging and blockage problems when used to handle raw domestic sewage.

The new valve is preferably installed so that the .expansible chamber in the valve housing is disposed above the flow passage with which the chamber communicates. Any debris which may find its way into the chamber during operation of the pump will'settle into the flow passage when the pump has been shut down. The debris will then be automatically flushed out of the valve during the next cycle of the pump.

Other objects, features and advantages of the invention will be had by reference to the following detailed description and the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of a sewage lift station embodying the air release valve of the present invention;

FIG. 2 is an enlarged top plan view of the new valve;

FIG. 3 is a vertical cross-sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a side elevational view taken along the line 44 of FIG. 3; and 1 FIGS. 5, 6 and 7 are cross-sectional views of the valve illustrating different stages of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and to FIG. 1 in particular, there is shown a sewage pumping system which includes a conventional self-priming centrifugal pump such as disclosed in U.S. Pat. No. 3,575,521. In the illustrated arrangement the pump 10 is disposed above a wet wall 11 which collects the sewage to be pumped. A suction inlet line 12 is connected to the intake side of the pump 10 and extends down into the wet wall 11. A discharge main 13 is connected to the discharge outlet of the pump 10 and extends upwardly. The discharge main 13 is provided with a one-way check valve 14 which prevents the liquid downstream from the valve from returning to the pump 10 when it has been shut down or is not operating at rated capacity and head.

The pump 10 is driven by an electric motor 15 operated through suitable electric controls 16.

An air release valve constructed in accordance with the present invention is installed in the illustrated pumping system between the pump 10 and the check valve 14 so that the inlet of the valve 20 communicates with the discharge outlet of the pump 10 through the main 13. An exhaust line 21 is connected to the outlet port of the valve 20 and extends into the wet well 13. The purpose of the valve 20 is to vent the air and liquid which is evacuated from the suction inlet pipe 12 and the pumping chamber of the pump 10. The valve 20 automatically closes when the pump is fully primed to prevent the venting of liquid through the valve during the pumping cycle.

Reference is now made to FIGS. 2, 3 and 4 which illustrate the preferred construction of. the new air release valve 20. As shown, the valve 20 comprises a housing 22 which includes a main body 23 and a cap 24. The cap 24 is connected to one end of the body 23 by screws 25. The valve 20 has an inlet port 26 in the cap 24 adapted to be connected to the discharge main 13 by an auxiliary pipe 27 and an outlet port 28 in the body 23 adapted to be connected to theexhaust line 21.

The interior of the housing 22 has a bore 33 which is formed in the end of the body 23 opposite to the cap 24. The bore 33 terminates at the outlet port 28. A fluid passageway 34 in the body 23 communicates with the inlet port 26 and has a mouth intersecting the bore 33 near the outlet port 28. The passageway 34 and a portion of the bore 33 define a through fluid flow passage connecting the

ports

26, 28. In the preferred construction of the invention, the

flow passage

33, 34 has a minimum diameter of one inch and a maximum angular flow exchange of 45. This preferred construction has been found to avoid all plugging and blockage problems when the valve is used in pumping systems handling raw domestic sewage.

The valve 20 is opened and closed by movement of a valving rod 35 which has one end portion reciprocally disposed in the bore 33. The valving rod 35 is movable between a closed position as shown in FIG. 6 in which the end of the rod blocks the mouth of the passageway 34 and an open position shown in FIG. 7 in which the end of the rod is withdrawn in the bore 33 so that the mouth of the passageway 34 is uncovered. This construction in which the rod'35 is withdrawn from the fluid flow path when the valve is open contributes to the clogging-free performance of the valve. In some conventional air release valves, the construction is such that the liquid flows through the valve around the valving element so that the valve is easily plugged by stringy material and other debris.

The valving rod 35 is actuated to its closed position by movement of a flexible diaphragm 36 which is mounted in a cavity formed by the inside surfaces of the cap 24 and the end of the body 23 to which the cap is connected. The diaphragm 36 is held in place by clamping its marginal edge between cooperating flanges of the body 23 and the cap 24. As shown, the valving rod 35 sidably extends through a wall 37 of the housing body 23 into the cavity in which the diaphragm is mounted. The central part of the diaphragm 36 is clamped between a pair of

plates

42, 43 which are secured by a nut 44 to a reduced diameter, threaded end portion of the valving rod 35.

The diaphragm 36 cooperates with the inside of the cap 24 to define an expansible pressure chamber 45. An auxiliary chamber 46 is formed inside of the cap 24 next to the pressure chamber. This auxiliary chamber 46 is located between the inlet port 26 and the fluid passageway 34 and opens into one side of the expansible chamber 45 so that fluid entering the inlet port can flow into chamber 45 and generate pressure to flex the diaphragm 36 and move the valving rod 35 to its closed position. The chamber between the diaphragm 36 and the end of the body 23 is vented to the atmosphere by a hole 47 extending through the body wall 37.

Access is provided into the expansible pressure chamber 45 by a clean-out opening 48 through the top of the cap 24. The opening 48 is normally closed by a plate 49 which is secured in place by screws 50.

The valving rod 35 is urged to its open position shown in FIGS. 2, 5 and 7 by a spring 52 which surrounds a central portion of the rod. One end of the spring 52 abuts a wall 53 of the housing body 23. The other end of the spring 52 engages an abutment washer 54 which is connected to the valving rod 35. In the illustrated and preferred embodiment of the invention, the washer 54 is adjustable along the length of the rod 35 toward and away from the wall 53 in order to change the spring loading of the valve. To this end, the rod 35 is formed with a series of holes 55 which are spaced axially of the rod. A pin 56 is adapted to be fitted through any one of these holes 55 in order to hold the washer 54 in a selected position.'

When the pump 10 of the system shown in FIG. 1 is shut down, its pumping chamber. is open to the atmosphere and the valve 20 is held in its open position due to the fact that the pressure in the valve chamber 45 is insufficient to overcome the spring 52. Upon the start up of the pump, air from the pumping chamber will be forced out through the open valve as shown in FIG. 5, since the downstream check valve. 14 will be held closed by the back pressure of the system head. As the pumpoperation continues, liquid will begin to flow with the air until sufficient pressure has been generated in the chamber 45 to overcome the spring force. At that time the pump will have been fully primed and the diaphragm will be forced to the position of FIG. 6 to move the valving rod 35 to its closed position. Premature closing of the valve can be prevented to assure full prime by proper preload adjustment of the

spring assembly

52, 54, 55, 56. Y

Continued operation of the pump 10 causes all of the liquid pumped from the wet wall 11 to be forced through the discharge main l3 past-the check valve 14. When the pump is next shut down, the pressure in the valve chamber 45 is relieved so that the valve 20 is automatically opened by the spring 52. With the valve open, the system is conditioned for the next pumping cycle or priming cycle if the suction leg in the pipe 12 drops during the shut down period.

As will be seen from the foregoing description, the valve 20 is pressure responsive rather than flow responsive due to the large difference in pressure areas between the diaphragm 36 and the end of the valving rod 35 in the bore 33. This pressure responsive characteristic of the valve 20 is an important feature because it assures full opening and closing movement of the valving rod and minimized hydraulic chattering. Hydraulic chattering is a common defect of conventional valve designs in which a hydraulically balanced condition can occur, especially during low pressure operation.

Since the valve 20 is pressure responsive in operation, it can be installed in any position. Preferably, however, the valve is installed in a horizontal position as shown in FIGS. 5-7 in order to obtain a self-flushing action when the valve is cycled. In the illustrated position, the expansible pressure chamber 45 of the valve 20 is above the auxiliary chamber 46. Any debris which finds its way into the valve while it is closed as shown in FlG. 6 will remain suspended in the chamber 45 and- /or will be held in the passageway 34 and the chamber 46 until the pump is shut down. When the pump is shut down and the valve opens as shown in FIG. 7, the movement of the diaphragm will force any debris out of the chamber 45 into the chamber 46 and the debris will be completely flushed out of the valve the next time the pump is started. lt will thus be seen that the invention achieves the objective of providing a reliable valve capable of being used in pumping systems handling raw sewage with contained solids.

Many variations and modifications of the invention will be apparent to those skilled in the art in view of the foregoing detailed disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the invention can be practiced otherwise than as specifically shown and described.

What is claimed is:

1.1n a pumping system including a self-priming pump having an inlet and an outlet, a check valve downstream from said outlet, and an air release valve operatively arranged between said outlet and said check valve for permitting the flow of fluid therethrough when said check valve is closed, the improvement wherein said air release valve comprises:

a. a housing having an inlet port connected to said pump outlet, an outlet port communicating to exhaust, and a flow passage extending between said ports,

b. a valving plug reciprocally mounted in said housing for pressure responsive movement between a closed position in which an end portion of said plug extends into and blocks said flow passage and an open position in which said end portion of said plug is withdrawn from said passage so as to permit unobstructed flow, and

c. actuating means for causing movement of said plug between said positions,

d. said actuating means including movable means mounted in said housing to define an expansible chamber communicating with one of said ports,

e. said movable means being connected to said plug at a location remote from said passage and said one end portion and being movable by pressure generated in said chamber to move said plug to one of said positions.

2. The improvement as claimed in claim 1 in which said chamber is disposed above said flow passage so that debris in said chamber will settle into said flow passage and be flushed from said valve when it is opened and said pump is actuated.

3. The improvement as claimed in claim 1 in which the maximum angular flow change of said passage is 45.

4. The improvement as claimed in claim 1 in which said housing has a clean-out opening into said chamber and includes a removable cover for said opening.

5. In a pumping system including a self-priming pump having an inlet and an outlet, a check valve downstream from said outlet, and an air release valve operatively arranged between said outlet and said check valve for permitting the flow of fluid therethrough when said check valve is closed, the improvement wherein said air release valve comprises:

a. a housing having inlet and outlet ports and a through flow passage connecting said ports,

b. a valving rod reciprocally mounted in said housing for movement between a closed position in which one end of said rod blocks said passage and an open position in which said end portion of said rod is withdrawn from said passage so as to permit unobstructed flow,

0. a diaphragm mounted in said housing to define:

i. an expansible pressure chamber on one side of the said diaphragm having an opening in communication with said inlet port and said passage,

ii. a chamber on the other side of said diaphragm which is vented to the atmosphere,

d. means connecting said diaphragm to said rod so that the pressure generated in said expansible chamber will cause said diaphragm to move said rod to one of said positions, and

e. biasing means resiliently urging said rod to the other of said positions.

6. The improvement as claimed in claim 5 in which said expansible chamber is disposed above said flow passage so that debris in said expansible chamber will settle into said flow passage and be flushed from said valve when it is opened and said pump is actuated.

7. In a pumping system including a self-priming pump having an inlet and an outlet, a check valve downstream from said outlet, and an air release valve operatively arranged between said outlet and said check valve for permitting the flow of fluid therethrough when said check valve is closed, the improvement wherein said air release valve comprises:

a. a housing having inlet and outlet ports, a bore terminating at said outlet port, and a fluid passageway extending from said inlet port to a mouth intersecting said bore,

b. a valving rod reciprocally mounted in said bore for movement between a closed position in which one end of said rod blocks the mouth of said passageway and an open position in which the mouth of said passageway is uncovered so as to permit unobstructed flow,

c. a diaphragm mounted in said housing to define:

i. an expansible pressure chamber on one side of said diaphragm having a side opening in commu nication with said inlet port and said passageway,

ii. another chamber on the other side of said diaphragm which is vented to the atmosphere,

d. said valve being positioned so that said expansible chamber is disposed above said passageway, whereby debris in said expansible chamber entering from said inlet port will settle into said flow passage and be flushed from said valve when it is opened and said pump is actuated,

e. means connecting said diaphragm to said rod so that pressure generated in said expansible chamber will cause said diaphragm to move said rod to said closed position of said valve, and

f. means resiliently urging said rod to said open position of said valve.

8. The improvement as claimed in claim 7 wherein said passageway and a portion of said bore cooperate to define a through fluid flow passage having a maximum angular flow change of about 45.

9. The improvement as claimed inclaim 8 wherein said fluid flow passage has a minimum diameter of about 1 inch.

10. A pressure responsive flow control valve comprising:

a. a housing having first and second ports and a through flow passage connecting said ports,

b. a valve plug reciprocally mounted in said housing for movement between a closed position in which a portion of said plug extends into and blocks said passage and an open position in which said plug is withdrawn from said passage so as to permit unobstructed flow, and

c. acutating means for causing movement of said plug between said positions,

e. said movable means being connected to said plug at a location spaced from said passage andbeing movable by pressure generated in said chamber to move said plug to one of said positions.

1]. A pressure responsive flow control valve comprising:

b. a valving plug reciprocally mounted in said housing for pressure responsive movement between a closed position in which a portion of said plug extends into and blocks said passage and an open position in which said portion of said plug is withdrawn from said passage so as to permit unobstructed flow, and

c. actuating means for causing movement of said plug between said positions,

d. said actuating means including a flexible diaphragm mounted in said housing to define:

i. an expansible pressure chamber on one side of said diaphragm having a side opening communicating with said passage and said inlet port,

e. said diaphragm being connected to said plug and being movable by pressure generated in said expansible chamber to move said plug to one of said positions.

12. The valve as claimed in claim 11 in which said passage has a maximum angular flow change of about 45.

13. A pressure responsive flow control valve comprising:

b. a valving rod reciprocally mounted in said bore for movement between a closed position in which a portion of said rod blocks the mouth of said passageway and an open position in which the mouth of said passageway is uncovered so as to permit unobstructed flow,

c. a diaphragm mounted in said housing to define:

i. an expansible pressure chamber having a side opening in communication with said passageway in said inlet port,

d. means connecting said diaphragm to said rod so that pressure generated in said expansible chamber will cause said diaphragm to move said rod to said closed position, and

e. biasing means resiliently urging said rod to said open position. I

14. A valve as claimed in claim 13 wherein said passageway and a portion of said bore cooperate to define a through fluid flow passage having'a maximum angular flow change of about 45.

15. A valve as claimed in claim 13 in which said housing has a clean-out opening providing access into said expansible chamber, and a removable cover for said clean-out opening.

Claims

1. In a pumping system including a self-priming pump having an inlet and an outlet, a check valve downstream from said outlet, and an air release valve operatively arranged between said outlet and said check valve for permitting the flow of fluid therethrough when said check valve is closed, the improvement wherein said air release valve comprises: a. a housing having an inlet port connected to said pump outlet, an outlet port communicating to exhaust, and a flow passage extending between said ports, b. a valving plug reciprocally mounted in said housing for pressure responsive movement between a closed position in which an end portion of said plug extends into and blocks said flow passage and an open position in which said end portion of said plug is withdrawn from said passage so as to permit unobstructed flow, and c. actuating means for causing movement of said plug between said positions, d. said actuating means including movable means mounted in said housing to define an expansible chamber communicating with one of said ports, e. said movable means being connected to said plug at a location remote from said passage and said one end portion and being movable by pressure generated in said chamber to move said plug to one of said positions.

3. The improvement as claimed in claim 1 in which the maximum angular flow change of said passage is 45*.

5. In a pumping system including a self-priming pump having an inlet and an outlet, a check valve downstream from said outlet, and an air release valve operatively arranged between said outlet and said check valve for permitting the flow of fluid therethrough when said check valve is closed, the improvement wherein said air release valve comprises: a. a housing having inlet and outlet ports and a through flow passage connecting said ports, b. a valving rod reciprocally mounted in said housing for movement between a closed position in which one end of said rod blocks said passage and an open position in which said end portion of said rod is withdrawn from said passage so as to permit unobstructed flow, c. a diaphragm mounted in said housing to define: i. an expansible pressure chamber on one side of the said diaphragm having an opening in communication with said inlet port and said passage, ii. a chamber on the other side of said diaphragm which is vented to the atmosphere, d. means connecting said diaphragm to said rod so that the pressure generated in said expansible chamber will cause said diaphragm to move said rod to one of said positions, and e. biasing means resiliently urging said rod to the other of said positions.

7. In a pumping system including a self-priming pump having an inlet and an outlet, a check valve downstream from said outlet, and an air release valve operatively arranged between said outlet and said check valve for permitting the flow of fluid therethrough when said check valve is closed, the improvement wherein said air release valve comprises: a. a housing having inlet and outlet ports, a bore terminating at said outlet port, and a fluid passageway extending from said inlet port to a mouth intersecting said bore, b. a valving rod reciprocally mounted in said bore for movement between a closed position in which one end of said rod blocks the mouth of said passageway and an open position in which the mouth of said passageway is uncovered so as to permit unobstructed flow, c. a diaphragm mounted in said housing to define: i. an expansible pressure chamber on one side of said diaphragm having a side opening in communication with said inlet port and said passageway, ii. another chamber on the other side of said diaphragm which is vented to the atmosphere, d. said valve being positioned so that said expansible chamber is disposed above said passageway, whereby debris in said expansible chamber entering from said inlet port will settle into said flow passage and be flushed from said valve when it is opened and said pump is actuated, e. means connecting said diaphragm to said rod so that pressure generated in said expansible chamber will cause said diaphragm to move said rod to said closed position of said valve, and f. means resiliently urging said rod to said open position of said valve.

8. The improvement as claimed in claim 7 wherein said passageway and a portion of said bore cooperate to define a through fluid flow passage having a maximum angular flow change of about 45*.

9. The improvement as claimed in claim 8 wherein said fluid flow passage has a minimum diameter of about 1 inch.

10. A pressure responsive flow control valve comprising: a. a housing having first and second ports and a through flow passage connecting said ports, b. a valve plug reciprocally mounted in said housing for movement between a closed position in which a portion of said plug extends into and blocks said passage and an open position in which said plug is withdrawn from said passage so as to permit unobstructed flow, and c. actuating means for causing movement of said plug between said positions, d. said actuating means including movable means mounted in said housing to define an expansible chamber communicating with one of said ports, e. said movable means being connected to said plug at a location spaced from said passage and being movable by pressure generated in said chamber to move said plug to one of said positions.

11. A pressure responsive flow control valve comprising: a. a housing having inlet and outlet ports and a through flow passage connecting said ports, b. a valving plug reciprocally mounted in said housing for pressure responsive movement between a closed position in which a portion of said plug extends into and blocks said passage and an open position in which said portion of said plug is withdrawn from said passage so as to permit unobstructed flow, and c. actuating means for causing movement of said plug between said positions, d. said actuating means including a flexible diaphragm mounted in said housing to define: i. an expansible pressure chamber on one side of said diaphragm having a side opening communicating with said passage and said inlet port, ii. another chamber on the other side of said diaphragm which is vented to the atmosphere, e. said diaphragm being connected to said plug and being movable by pressure generated in said expansible chamber to move said plug to one of said positions.

12. The valve as claimed in claim 11 in which said passage has a maximum angular flow change of about 45*.

13. A pressure responsive flow control valve comprising: a. a housing having inlet and outlet ports, a bore termiNating at said outlet port, and a fluid passageway extending from said inlet port to a mouth intersecting said bore, b. a valving rod reciprocally mounted in said bore for movement between a closed position in which a portion of said rod blocks the mouth of said passageway and an open position in which the mouth of said passageway is uncovered so as to permit unobstructed flow, c. a diaphragm mounted in said housing to define: i. an expansible pressure chamber having a side opening in communication with said passageway in said inlet port, ii. another chamber on the other side of said diaphragm which is vented to the atmosphere, d. means connecting said diaphragm to said rod so that pressure generated in said expansible chamber will cause said diaphragm to move said rod to said closed position, and e. biasing means resiliently urging said rod to said open position.

14. A valve as claimed in claim 13 wherein said passageway and a portion of said bore cooperate to define a through fluid flow passage having a maximum angular flow change of about 45*.