US3635239A

US3635239A - Gas supply shutoff valves

Info

Publication number: US3635239A
Authority: US
Inventors: Sydney Farrer
Original assignee: Bryan Donkin Co Ltd
Current assignee: Bryan Donkin Co Ltd
Priority date: 1969-03-19
Filing date: 1970-03-16
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18
Also published as: DE2012989A1; GB1244805A

Abstract

A gas supply shutoff valve including a valve member hingedly mounted within a main body part; a detent mechanism including a linkage arrangement for retaining said valve member in an inoperative position, the linkage arrangement moving ''''overcenter'''' when the valve is closed; and means for tripping the detent mechanism to cause the valve to shut.

Description

United States Patent Farrer [4 Jan. 18, 1972 [54] GAS SUPPLY SHUTOFF VALVES References Cited [72] Inventor: Sydney Farrer, Sheffield, England UNITED STATES PATENTS [73] Assignee: The Bryan Donkin Company Limited, 2,426,364 8/1947 Maggecar ..137/458 Chesterfield, England 2,229,543 1/1941 Bailey .127/458 X 948,445 2/1910 Golden 137/462 [221 1970 2,344,583 3 1944 Annin ..137/462 [21] Appl. No.: 19,805

Primary Examiner-Harold W. Weakley Attorney-Jacobs & Jacobs [30] Forelgn Appllcgilon Priority Data Mar. 19, 1969 Great Britain ..l4,483/69 [571 ABSTRACT A gas supply shutoff valve including a valve member hingedly [52] 11.8. CI. ..137/46l, 137/462, 137/463 mounted within a i body part; a detent mechanism i [51 ll!!- Cl ..Fl6k 117/02 ing a linkage arrangement for retaining said valve member in [58] Field of Search ..137/458,461,462, 463 an imperative position, the linkage arrangement moving overcenter when the valve is closed; and means for tripping the detent mechanism to cause the valve to shut.

6 Claims, 5 Drawing Figures III) PATENTEU JAN 1 8 1972 SHEET 2 OF 5 INVENTOQ 570MB) fleas/a QMQ QWA/ I PATENTEU JAN 1 8 I972 SHEET 3 [IF 5 PATENIEB MN I 8 i972 SHEET 5 BF 5 W h m w H n N M & m1 mm F |.|L P Ow. Om m mv\hu IN VENTOP SyQA/Ey @flzsirc GAS SUPPLY SHUTOFF VALVES The invention relates to gas supply shutoff valves and has for its object to provide an improvement therein.

According to the invention, there is provided a gas supply shutoff valve including a valve member hingedly mounted within a main body part; a detent mechanism for retaining said valve member in an inoperative position, said detent mechanism including a linkage arrangement arranged to move overcenter when the valve is closed; and means for tripping the detent mechanism to cause the valve to shut in response to an excess pressure signal transmitted from some gauge point downstream of the valve, a seal which is formed between the valve member and a seat when the valve is closed being sufficiently resilient to ensure that after the linkage arrangement has moved overcenter there is provided a gastight seal. The means for tripping the detent mechanism will preferably in clude an actuating unit provided with a flexible diaphragm against which a gauge pressure is caused to act. Preferably, also, an adjustable spring acts on said diaphragm in opposition to said gauge pressure. The detent mechanism may include a roller carried by one of the links of the linkage arrangement, said roller being capable of acting against a trip lever under the control of the actuating unit. In addition to the valve being caused to shut in response to an excess pressure signal trans mitted from some gauge point downstream of the valve, means may be provided to cause shutoff in response to excess pressure in the valve itself. Such means may include a valve which can be arranged to open in response to a predeterminedly high pressure in said valve to permit said high pressure to act against the flexible diaphragm and may also include a restricting orifice in a pipe communicating with the gauge point downstream of the valve.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which:

FIG. 1 is a longitudinal section through a shutoff valve embodying the invention,

FIG. 2 is a scrap view illustrating a modification which may be made to the valve illustrated in FIG. 1.,

FIG. 3 is a scrap view illustrating an alternative modification which may be made,

FIG. 4 is a schematic view showing the valve installed in a gas supply line, and

FIG. 5 is a view similar to FIG. 4 but showing a modification which may be made.

Referring now to FIG. 1 of the drawings, a safety shutoff valve for installation in a gas supply system includes a main body part with coaxial inlet and outlet passages indicated 12 and 14 respectively. A valve member generally indicated 16 is pivotally mounted within the body part about the axes of oppositely disposed spigots 18 of screwed plugs (not shown) which are screwed into the body part, said spigots engaging the opposite ends of a tube 20 which is welded to one end of an arm 22. The tube 20 and arm 22, together with spigots l8, constitute a hinge mounting for the valve member 16.

The valve member 16 is provided with a sheet metal pressing 24 with an annular lip 26 formed integrally with it. An annular disc 28 is welded to the inwardly dished surface of the pressing 24 to form an annular space 30 which is filled with a resilient material. A seating ring 32 is screw-threaded into the upstream end of the outlet passage as shown and is provided with an annular projection 34 constituting a valve seat arranged to bite into the resilient material filling the space 30 in the door, thereby providing a good gastight seal when the valve member has been closed. A screw-threaded spindle 36 is provided for securing the valve member to the arm 22, and said spindle is surrounded by a pair of abutting rubber bushes 38 where it extends through a hole in said arm. This improves still further the seal which is made when the valve member has been closed, since the valve member is able to adjust its position upon the valve seat.

A detent mechanism arranged to retain the valve member in the raised inoperative position in which it is shown in chaindotted lines in FIG. 1 is constituted by a trip lever 40 pivotally mounted at 42 in a bracket 44 depending from an upper wall 45 of the main body; a roller 46 abutting a notched part 50 of the trip lever; a roller carrier assembly comprising a link 52 secured at one end to a pair of plates 48; a bracket 54 projecting from the arm 22 and pivotally connected to the other end of the link 52; and a further link 56 pivotally mounted at one end to the roller carrier assembly and pivotally mounted at its other end about the axis of a spindle 58. A spring 60 encircles the spindle 58 and acts against the link 56, the arrangement being such that when the detent mechanism is tripped, that is to say released, the spring acts to cause the valve member to be slammed shut upon its seat, being assisted in this of course by any flow of gas which there may be through the valve as the valve member approaches its seat. It will be seen that, in slamming shut, the valve member causes the linkage arrangement constituted by the links 52 and 56 to move overcenter" and a pin 62 which is also mounted between the plates 48 abuts against the link 56 to retain the links in a near straight condition so that the valve member is held hard upon its seat.

Means for tripping the detent mechanism in response to an excess pressure signal include an actuating unit generally indicated 64. The actuating unit includes a body part 66 surmounting the main body part 10 and provided with a flexible diaphragm 68. A space above the diaphragm is open to atmosphere but a space between the diaphragm and the upper wall 45 of the main body part constitutes a gauge pressure chamber 70 the pressure within which acts in opposition to the force of a spring 72 which bears downwardly upon the diaphragm and reacts against an adjusting screw 74. A spindle 76 which is connected at its upper end to the diaphragm extends slidably through a bush 78 and at its lower end is connected to a fork member 80 between the arms of which a roller 82 is mounted. The arms of the fork member straddle the trip lever and the roller bears against an upper part of the surface of an aperture 84 which is considerably larger than the roller as shown. The bush 78 is recessed as shown for the reception of a rubber O-ring 86 which surrounds the spindle 76, and the O-ring is retained in position by means of a cap 88 screwed on the lower end of the bush.

Referring now to FIG. 4, an excess pressure signal can be transmitted to the actuating unit 64 from a point some distance downstream of the valve by means of an impulse pipe 90. As shown, this point may be downstream of a pressure regulator generally indicated 92 or of some other control. A tapping 94 is provided through the wall of the main body part 10, breaking into the gauge pressure chamber 70, for the connection of the impulse pipe.

During normal operation, the valve member 16 is latched up in its inoperative position out of the main gas stream by the detent mechanism. However, if the pressure in the chamber 70 exceeds a predetermined maximum, this pressure of course being related to the pressure at the gauge point downstream of the valve, the detent mechanism is tripped by the actuating unit 64 so that the valve member is immediately slammed shut by the spring 60. (The force of the spring 72 can of course be adjusted by the adjusting screw 74, when a top cap 96 has been removed, to vary the pressure at which the detent mechanism will be tripped). As previously described, the links 52 and 56 move overcenter" as the valve is shut, but the valve can be reopened and the mechanism reset when normal operating conditions have been reestablished by turning the spindle 58 in an anticlockwise direction when viewed as in FIG. 1.

Referring now to FIG. 2, in a modification of the valve just described the spindle 76 has been replaced by a very slender rod 98 an upper end of which is fitted with a button-type washer 100 of resilient material arranged to form a seal between the underside of the diaphragm and on orifice-type nozzle 102 formed on the upper end of the bush 78. The valve is of course arranged to operate in substantially the same way as before but it is thought that the reliability of the valve (after perhaps years of use without once having had to shut ofi the gas supply) may be improved due to the elimination of the O- ring seal 86 which despite lubrication can be a source of sticking.

An alternative method of eliminating the O-ring seal is shown in FIG. 3 where the spindle 76 has been replaced by a slender tension wire 104 connected at its upper end to the flexible diaphragm and at its lower end to a retaining block 106 carried by a flexible metallic strip 108. The retaining block and flexible strip 108 (the latter of which is secured at one end beneath a lug 110 formed within the main body part) together constitute a trip lever which replaces the pivoted trip lever 40. This eliminates a further possible source of sticking after years of service. in this case also a button-type washer 100 is used to make contact with the upper end of the bush 78. In additionto this there is a resilient washer 112 encircling the tension wire 104 and held in contact with the underside of the bush 78 by means of a light compression spring 114 which reacts against the retaining block. An important feature of this latter arrangement is the ability of the tension wire 104 to move slightly from side to side without affecting the sealing means employed.

In a still further modification, as illustrated in FIG. 5, the arrangement is such that the detent mechanism will be tripped by the actuating unit 64 in response to an excessively high inlet pressure. In this case, there is provided a spring closed valve generally indicated 116 which can be arranged to open in response to a predeterminedly high pressure in the outlet passage 14, the valve opening to allow the flow of gas under pressure through a pipe 118 communicating with the impulse pipe 90. A restricting orifice 120 is disposed in the impulse pipe on the downstream side of the point at which the pipe 1 18 breaks into it so that a flow of gas under pressure through the pipe 118 quickly builds up a pressure of gas within the chamber 70 so that the detent mechanism is tripped. Of course, the presence of the restricting orifice does not interfere with the normal very slight flow of gas through the impulse pipe 90 to and from the chamber 70 to maintain a gas pressure within said chamber equal to that at the gauge point I some distance downstream of the valve.

Thus there is provided a safety cutoff valve which it is thought will be very effective in operation, even after many years of use under normal operating conditions, to cause a positive shut off in response to predetermined high-pressure conditions. in this connection it should be noted that after the linkage arrangement has moved overcenter there is provided a gastight seal from negligible pressure difference up to the full rated pressure without grease sealing or auxiliary sealing means. In addition, it will be seen that the arrangement provides a full bore opening to gas flow during normal operating conditions and that there are fail-safe characteristics which commend the design of valve illustrated in the drawings. For example, if the spring 60 should break the valve member can fall from its raised, inoperative position towards its lower, closed position under the force of gravity and can of course be assisted by gas flow through the valve. Similarly, if the spring 72 should break the detent mechanism will be tripped and the valve fails to safety.

Various other modifications may be made without departing from the scope of the invention. For example, the valve member may be mounted in numerous different ways and the overcenter" and detent mechanisms may also be modified in various ways. The valve member itself may of course be constructed in various ways but it will be understood that it might be as light as possible consistent with strength requirements. The form of construction described and illustrated by way of example has been found to fulfill both these requirements but other constructions may be found to be equally effective.

What is claimed is:

l. A gas supply shutoff valve including a main body part; a valve member within said body part; a valve seat within said body part against which the said valve member can close; a hinge mounting between said body part and said valve member; a detent mechanism for retaining said valve member in an inoperative position; means responsive to an excess pressure signal transmitted from some gauge point downstream of the valve for tripping the detent mechanism to cause the valve member to shut against the valve seat; a linkage arrangement pivotably connected between the body part and the valve member; and resilient material for forming a gastight seal between said valve member and the valve seat when the valve has been closed, the linkage arrangement being such that it can move overcenter when the valve member has been closed onto the valve seat, and the resilience of the resilient material in relation to the characteristics of linkage arrangement being such as to ensure that after the linkage arrangement has moved overcenter there is still provided a gastight seal.

2. A gas supply shutoff valve according to claim 1, further characterized in that the means for causing the valve to shut in response to an excess pressure signal include an actuating unit provided with a flexible diaphragm against which a gauge pressure is caused to act.

3. A gas supply shutoff valve according to claim 2, further characterized in that an adjustable spring acts on said diaphragm in opposition to said gauge pressure.

4. A gas supply shutoff valve according to claim 1, further characterized in that the detent mechanism includes a roller carried by one of the links of the linkage arrangement, said roller being capable of acting against a trip lever under the control of the actuating unit.

5. A gas supply shutoff valve according to claim 1, further characterized in that in addition to the valve being caused to shut in response to an excess pressure signal transmitted from some gauge point downstream of the valve, additional shutoff means are provided to cause shut off of the valve in response to excess pressure in the valve itself.

6. A gas supply shutoff valve according to claim 5, further characterized in that said additional shut off means include a normally closed valve means arranged to open in response to a predeterminedly high pressure in said valve, said responsive means being operably associated with said valve means for tripping the detent mechanism when said valve means is opened, and a restricting orifice in a pipe communicating with the gauge point downstream ofthe valve.

Claims

1. A gas supply shutoff valve including a main body part; a valve member within said body part; a valve seat within said body part against which the said valve member can close; a hinge mounting between said body part and said valve member; a detent mechanism for retaining said valve member in an inoperative position; means responsive to an excess pressure signal transmitted from some gauge point downstream of the valve for tripping the detent mechanism to cause the valve member to shut against the valve seat; a linkage arrangement pivotably connected between the body part and the valve member; and resilient material for forming a gastight seal between said valve member and the valve seat when the valve has been closed, the linkage arrangement being such that it can move ''''overcenter'''' when the valve member has been closed onto the valve seat, and the resilience of the resilient material in relation to the characteristics of linkage arrangement being such as to ensure that after the linkage arrangement has moved ''''overcenter'''' there is still provided a gastight seal.

6. A gas supply shutoff valve according to claim 5, further characterized in that said additional shut off means include a normally closed valve means arranged to open in response to a predeterminedly high pressure in said valve, said responsive means being operably associated with said valve means for tripping the detent mechanism when said valve means is opened, and a restricting orifice in a pipe communicating with the gauge point downstream of the valve.