US3830250A - Valve proving system - Google Patents

Abstract

The invention relates to a valve proving system. A duct is connected to the valve casing, between the inlet and outlet to collect leakage. Means is provided to ensure that when the valve is closed the pressure in the duct is initially low and means is also provided to produce a response when the pressure in the duct exceeds a predetermined value.

Description

United States Patent 1191 Smith 1451 Aug. 20, 1974 VALVE PROVING SYSTEM [75] Inventor: William Arthur Smith, London,

England [73] Assignee: Babcock & Wilcox Limited, London,

England [22] Filed: May 12, 1972 [21] Appl. No.: 252,563

[30] Foreign Application Priority Data May 14, 1971 Great Britain 15070/71 [52] US. Cl 137/312, 73/46, 137/628 [51] Int. Cl. Fl6k 51/00 [58] Field of Search 137/312, 557; 73/405,

[56] References Cited UNITED STATES PATENTS 2,136,519 11/1938 OConnor ..25l/25X 310 3 VALVE 8/1968 Grove et a1. 137 312 3,51 1,082 5/1970 Lathrop et a1 73/46 3,605,792 9/1971 Westbrook 137/312 FOREIGN PATENTS OR APPLICATIONS 1,211,199 ll/l970 Great Britain 137/312 Primary Examiner-William R. Cline Assistant ExaminerRichard Gerard Attorney, Agent, or Firm-Joseph M. Maguire, Esq.; Robert .1. Edwards, Esq.

[57] ABSTRACT 6 Claims, 2 Drawing Figures SOL ENOID OPERATED 7 IS l8 THROTTLE KVALVE THROTTLE Kw: LVE 3 2a 5 ll VENTED GAS j Q/cneck VALVE /0115 VALVE fAlR OPERATED VALVE I5 27 PRESSURE sw1Tc1-1 FUEL VALVE #0 /4 FUEL VALVE ACTUATOR Pmmanwnzmw 59 SOLENOID OPERATED 3/0 3 VALVE 9% JMQQ/ICHECK VALVE I9 15 30 THRCTTLE KVALVE 2 gg/cnscx VALVE 330 fAlR OPERATED VALVE:

l5 PREssuR|-: 0b 1 a SWITCH vsm'en sAs/ l3 FUEL VALVE 0 #0 I2 \IFUEL VALVE- 5 ACTUATOR d. I I

VALVE PROVING SYSTEM This invention relates to valve proving systems and derives from a consideration of the problems arising in the design of gas-fired burner installations.

In a gas fired furnace having a tall flue, the flue, even when the furnace is idle, will tend to be raised by ambient conditions to a temperature higher than that of the furnace chamber. The resultant temperature differences will tend to result in currents establishing a negative pressure in the furnace chamber so that if the supply of gas to the furnace is controlled by a valve, and a leak caused by wear, for instance, has developed through the valve, then there will be a tendency for gas to be drawn into the furnace chamber. If there is no warning of the presence of gas in the chamber, and the ignition of the burners is initiated in the normal way, a risk of explosion arises.

By use of the present invention in association with a gas-fired furnace, for instance, it is possible, should a leak develop in the valve controlling the flow of gas to the furnace, to derive an indication of the fact so that remedial action can be taken. Apparatus embodying the invention may, it will be understood, be used in other contexts.

According to the present invention, there is provided a valve having a casing, an inlet to and an outlet from the casing, and means movable within the casing between an operative position in which a connection between the inlet and the outlet is established and an inoperative position in which the inlet and the outlet are obturated, and a valve proving system including a duct opening into the casing between the inlet and the outlet, means responsive to the pressure within the duct and arranged to produce a response when the pressure in the duct exceeds a certain value, exhaust means associated with the end of the duct remote from the casing that, on actuation, reduces the pressure in the duct and after actuation effects a closure of the end of the duct, and means whereby the exhaust means may be actuated when the valve is in its closed condition.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawing in which:

FIG. 1 shows schematically, valve proving apparatus, and

FIG. 2 shows a sleeve valve that may be used in a modification of what is shown in FIG. 1

In this embodiment a double block ball valve is included in the duct 11 by which gas is supplied to a furnace. The furnace is not shown in the drawings but may be assumed to discharge combustion gases through a boiler stack. When the furnace is inoperative, ambient temperature conditions will tend to lower the pressure in the stack so that there is positive pressure difference across the valve 10 that tends to draw gas into the furnace chamber. The valve includes a casing 12 having a spherical cavity and diametrically opposite inlet and outlet openings 12a and 12b respectively. A ball 13 is rotatable within the casing 12 and is penetrated by a passage that, when the valve is operative, connects the inlet and outlet openings and, when the valve is inoperative, lies transversely of the axisof the openings.

A spindle 14 by which the ball can be rotated is perpendicular to both that axis and the openings and extends through a seal 14a in the casing and a duct 15 opens into the casing at a point dimetrically opposite the seal. At its other end, the duct opens into a cylinder 16 in which a piston 17 is reciprocable. One or, for safety should one spring fail, several springs (indicated at 18), urge the piston 17 towards-the end of the cylinder remote from the end into which the duct opens and a seal 19 is formed between the piston and the cylinder. The seal used in the embodiment illustrated is provided by a flexible sleeve fixed at one end to the piston 17 and at the other end to the end of the cylinder 16 towards which the piston is urged by the springs. Between its ends, the sleeve is folded upon itself, the position of the fold relatively to the ends moving as the piston moves within the cylinder. The cylinder is provided, at the end to which the duct leads, with a one-way valve 20, flow through which facilitates the movement of the piston towards that end of the cylinder.

Between the cylinder 16 and the casing 12, the duct 15 includes a non-retum valve 25 and, upstream of that, a diaphgram-controlled isolating valve 26. Between the diaphragm-controlled valve 26 and the casing 12, a pressure responsive switch 27 is connected to respond to the pressure in the duct 15 and generate an audible or visible signal if the pressure exceeds a certain value.

The operation of the ball valve 10 is controlled pneumatically by air delivered through an air line 30 from a source (not indicated). Pressure in the line 30 acts through the actuator 34 to rotate the spindle 14 against the action of a restoring spring incorporated in the actuator 34 and which tends continuously to rotate the spindle 14 in the sense that closes the valve 10. Connection between the air line 30 and the source is through a solenoid controlled two-way valve 31 which in one conditionconnects the source to the line and in the other obturates the source and connects the line to a vent 31a. There extends from the line 30 to the end of the cylinder 16, on the side of the piston 17 opposite to that to which the duct 15 leads, a branch 32 and to the diaphragm-controlled valve 26, a branch 33. Eace of these branches contains an air flow restrictor 32a and 33a respectively to control the reactions of the piston and the diaphragm-controlled valve to the actuation of the valve that connects the air line 31 to the vent 31a.

Now suppose the furnace is to be brought into operation. The solenoid valve 31 is operated to connect the air line to the source. The pressure in the line 30 will open the ball valve 10 so that gas flows to the furnace. Pressure in the branch 33 will cause the isolating valve 26 to snap shut. Pressure in the branch 32 moves the piston in the cylinder in the direction that compresses the springs, gas or air on the spring side of the piston escaping through the pressure relief valve 20. If the ball 13 is a close fit in the casing 12 so that no unacceptable leak around it has developed, the pressure within the duct 15 will not rise to such a value as to actuate the pressure responsive switch 27.

the valve 10 has closed. Gas that may have been trapped in the valve will pass through the duct and escape through the pressure relief valve 20. When the pressure in the line has been relieved through the vent 31a, movement of the piston 17 under the action of the springs 18, at a rate controlled by the setting of the valve 32a, will then act to lower the pressure in the duct 15. The position of the piston 17 in the cylinder 16 will be determined by equilibrium between the effect of the springs and the pressure in the duct 15. Should there be a leakage into the casing 12 (as a result of wear for instance), between the inlet and the outlet of the gas control valve 10, gas will leak into the duct and so raise the pressure in the duct. Then the piston 17 will move under the action of the springs 18 to maintain equilibrium until the piston 17 reaches the end of its possible range of travel. Throughout this time, the pressure in the duct 15 is less than that at which the pressure responsive switch 27 operates. When the pressure increases beyond a predetermined value greater than the pressure that can be maintained by movement of, the piston, the valve 27 will open and cause an alarm to operate so that appropriate action can be taken to eliminate the valve or duct leakage indicated by the operation of the alarm.

In a modification of what has been described the diaphragm controlled valve 26 is replaced by a sleeve valve of which the rod 41 is connected to be positively moved by rotation of the shaft 14 of the valve 10, the position of the rod in the sleeve being dependent upon the orientation of the ball 13. The sleeve valve has an inlet 42 to which one part of the duct 15 is connected, and an outlet 43, to which the other part of the duct 15 is connected, the inlet and outlet being connected or obturated according to the position of the rod 41. The sleeve valve is also provided with a vent 44. When the gas valve is open the corresponding position of the rod 41 is such that the inlet 42, outlet 43, and vent 44 are closed by the rod 41. As the spindle 14 of the gas valve starts to rotate in closing the valve, it moves the rod 41 to the position in which it is shown in the drawing, in which the inlet 42 is connected to the vent 44, and the outlet 43 is closed. Further rotation of the shaft, to a position in which the inlet 12a and outlet 12b are obturated by the ball 13, causes the rod 41 to move to a position in which the inlet 42 and outlet 43 are connected so that movement of the piston 17 in the cylinder 16 under the action of the springs 18 exhausts the casing 12. Movement of the ball 13 to its final position is accompanied by movement of the rod 41 to a position in which it closes both the inlet 42 and the outlet 43 so that leakage after this into the casing 12 will create pressure in that part of the duct 15 that lies between the casing 12 and the valve 40 which, if the pressure becomes high enough, will cause an alarm to be given.

An advantage of the embodiment shown in FIG. 1 over the modification of FIG. 2 is that it does not require the bracket, and other components that may be required in the latter to establish a reliable connection between the spindle 14 and the rod 41 of valve 40, thus enabling the complete assembly of component parts to be erected on a small flat panel which may be mounted on pipe bracketing immediately adjacent to the ball valve and a single connection utilized to make the entry to the ball valve casing.

In the embodiments that have been described, piston 17 is moved by pressure in the line 30 and once the pressure has been removed, and the piston has moved to the extreme position to which it is urged by the springs 18, the increase of pressure in duct 15 will cause an alarm to sound and the apparatus will remain in this condition until remedial steps are taken. Now it may be that a slow rate of leakage into the casing, and hence into the furnace, could be tolerated. It is therefore envisaged that the piston and cylinder 16 might be replaced by a device, such as an electric pump, which would act to exhause the duct 15 but which could be re-activated automatically without the line 30 being put under pressure after the pressure responsive switch 27 had operated. In these circumstances infrequant operation of the alarm would be considered tolerable whilst action would be considered necessary if the alarm operated at a rate greater than an allowable maximum.

1 claim:

l. The combination of a fluid flow valve including a casing having an inlet and an outlet opening, a valving member disposed within the casing and movable between open and closed valve positions with respect to said openings, a system for removing fluid from within the casing when the valving member is in closed position, pressure responsive means for venting the system when the fluid pressure therein exceeds a predetermined value, said system comprising wall means defining a chamber, duct means flow connecting an end of said chamber with the casing space intermediate said openings, partition means movable within the chamber, and resilient means urging the partition means away from said chamber end, the duct means including an isolating valve having an open position to establish communication between said chamber and casing sapce, and a closed position to cut off communication therebetween, and pressure responsive means for generating a signal when the fluid pressure within the duct means exceeds a predetermined value, said last named value being less than that required for venting the system, a control circuit operatively associated with said fluid flow valve and system, and including means for actuating the valving member and isolating valve and partition means, the presence of said actuating means in the control circuit serving to open the flow valve and to close the isolating valve and to counteract said resilient means and move the partition means toward said chamber end, and the absence of said actuating means from the control circuit serving to close the flow valve and to open the isolating valve and to permit the resilient means to urge the partition means away from said chamber end to form a reservoir therebtween and reduce the pressure within said system.

2. The combination according to claim 1, wherein said actuating means is a pressurized fluid.

3. The combination according to claim 1, including throttling means disposed in the control circuit to delay the actuation of said isolating valve and partition means.

4. The combination according to claim 1, wherein said resilient means includes at least one spring member.

5. The combination according to claim 1, wherein the chamber is in the form of a cylinder and the partition means includes a disc member.

6. The combination according to claim 5, including a flexible sleeve forming a seal between said cylinder and disc member.

Claims (6)

1. The combination of a fluid flow valve including a casing having an inlet and an outlet opening, a valving member disposed within the casing and movable between open and closed valve positions with respect to said openings, a system for removing fluid from within the casing when the valving member is in closed position, pressure responsive means for venting the system when the fluid pressure therein exceeds a predetermined value, said system comprising wall means defining a chamber, duct means flow connecting an end of said chamber with the casing space intermediate said openings, partition means movable within the chamber, and resilient means urging the partition means away from said chamber end, the duct means including an isolating valve having an open position to establish communication between said chamber and casing sapce, and a closed position to cut off communication therebetween, and pressure responsive means for generating a signal when the fluid pressure within the duct means exceeds a predetermined value, said last named value being less than that required for venting the system, a control circuit operatively associated with said fluid flow valve and system, and including means for actuating the valving member and isolating valve and partition means, the presence of said actuating means in the control circuit serving to open the flow valve and to close the isolating valve and to counteract said resilient means and move the partition means toward said chamber end, and the absence of said actuating means from the control circuit serving to close the flow valve and to open the isolating valve and to permit the resilient means to urge the partition means away from said chamber end to form a reservoir therebtween and reduce the pressure within said system.

2. The combination according to claim 1, wherein said actuating means is a pressurized fluid.

3. The combination according to claim 1, including throttling means disposed in the control circuit to delay the actuation of said isolating valve and partition means.

4. The combination according to claim 1, wherein said resilient means includes at least one spring member.

5. The combination according to claim 1, wherein the chamber is in the form of a cylinder and the partition means includes a disc member.

6. The combination according to claim 5, including a flexible sleeve forming a seal between said cylinder and disc member.

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