GB2245957A - Valve operating mechanism - Google Patents

Abstract

A remote shut-down system for effecting closure of handwheel controlled valves of storage vessels containing toxic or hazardous fluids includes a pair of rotary shafts 41, 42 connected by a clutch mechanism 44 which, in the position shown, permits rotation of the shaft 42 on direct manual operation of the associated handwheel, and, in a second portion, locks the two shafts against relative rotation so as to permit remote actuation of the associated valve through rotation of the drive shaft 41. The two parts of the clutch are brought into engagement by rotation of a screw-threaded nut 66. Remote actuation is effected manually or in response to the detection of the presence of toxic fluid. <IMAGE>

Description

VALVE OPERATING MECHANISMS This invention relates to valve operating mechanisms particularly for effecting remote operation of valves controlling the egress of toxic or hazardous fluids from storage vessels.

Chlorine is commonly supplied in storage drums equipped with hand operable valves. If there is a leakage of chlorine downstream of the drum, it is essential that the drum outlet valve is closed rapidly and reliably without the need for an operator to approach the drum valve handwheel.

According to the present invention there is provided a valve operating mechanism comprising a connector adapted to be fitted to the handwheel of a storage vessel in drive transmitting relation with the handwheel, a rotary drive source and a shaft assembly connecting the drive source to the connector, the shaft assembly being in two parts interconnected by a coupling device which, in a first mode of operation, serves to transmit rotary drive between the two shaft parts and, in a second mode of operation, interconnects the shaft parts with axial play to allow them to be decoupled with respect to rotary drive.

In a presently preferred embodiment of the invention, the coupling device comprises a pair of clutch members, each rotatably fast with respective ones of the shaft parts and being movable relative to one another between an engaged position and a decoupled position.

The coupling device facilitates re-opening of the valve by means of the handwheel after the valve has been closed by the mechanism, ie. by allowing, in said second mode of operation, the shaft parts to be displaced axially relative to one another to facilitate release of the connector from the handwheel.

The drive source is conveniently a fluid powered motor which is supplied with fluid under pressure via a receiver or accumulator, means such as a compressor preferably being provided to maintain the fluid in the receiver or accumulator at a predetermined pressure sufficient to rotate the shaft assembly through as many revolutions as necessary to drive the handwheel from an open position to a fully closed position in the event that valve closure is required.

Preferably, at least one of the shaft parts is connected to the drive source and the connector respectively by a universal coupling.

Typically the handwheel of the storage vessel will include two or more openings and the connector comprises two or more projections for reception in these openings such that the projections can be inserted into and withdrawn from the handwheel in an axial direction.

Preferably operation of the mechanism to effect valve closure is triggered in response to actuation of a user-operable switch located remotely from the storage vessels and/or a detector sensitive to the fluid stored by the vessel. Thus, if there is a release of hazardous fluid from the vessel, shutdown may either be initiated manually or automatically.

The invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a plan view of a storage system for chlorine containing drums; Figure 2 is a side view showing one of the drums and part of the remotely operable shut-down mechanism associated with the drum; Figure 3 is a side view showing one form of coupling between the handwheel of a drum valve and part of the shut-down mechanism; and Figure 4 is a view of a clutch device forming part of the shut-down mechanism.

Referring to the Figure 1, there is shown a storage and supply system for chlorine stored in a number of drums 10 of conventional design. In accordance with standard practice, each drum is equipped with two hand operable valves 12, 14 by means of which chlorine in liquid or gaseous form can be tapped from the drums via outlets 16. In the embodiment shown, only the liquid supply valves 14 are intended to be used, the other valves being permanently closed in this case. However, it will be appreciated that the valve operating mechanism of the invention may be additionally or alternatively be used in conjunction with the valves 12, according to requirements. The drums 10 are mounted on racks 18 within an enclosure 20 which isolates the drums from the surroundings. The enclosure 20 can be accessed for drum replacement purposes via an entrance 22 equipped with a roller shutter door 24.

Each drum 10 has the handwheel of valve 14 coupled to a valve closure mechanism 26 comprising a connector 28 which is adapted to be fitted to the handwheel. As shown in Figure 3, the handwheel 30 has a number of openings 32 therein and the connector 28 has a number of correspondingly located prongs 34 so that the connector can be fitted with its prongs 34 inserted into the openings 32. When required, the connector can be separated from the handwheel by withdrawing the connector to displace the prongs in an axial direction.

Each connector 28 may be coupled by a universal coupling 36 to a torque tube 38 forming part of a shaft assembly interconnecting the connector 28 with a respective air motor 40. It may not be necessary to provide the universal coupling 36 if the prongs 34 are made sufficiently undersize with respect to the handwheel openings because the torque tube may then tilt relative to the connector 28. The torque tube 38 is connected to the output shaft 41 extending from a gear drive 43 associated with each air motor 40 by a universal coupling (part of which is depicted by reference numeral 42 in Figure 4) and a coupling device 44 which is shown in greater detail in Figure 4, the universal coupling being located between the torque tube and the coupling 44.The air motors 40 are connected in a pressurised fluid supply circuit and receive air under pressure from an accumulator 48 which is maintained at a predetermined pressure by an air compressor 46 to ensure that the air pressure available for supply to each of the air motors is at a substantially constant predetermined pressure. The air motors 40 are connected to the accumulator 48 via normally open valves 47 and normally closed valve 49. Thus, in normal operation of the drums, the drum valves 14 are open and the air motors are isolated from the accumulator 48 by the valve 49. The valves 47 are normally open but may be closed when the respective drum is to be disconnected and replaced.

A control circuit (not shown) is provided which, in normal operation of the system, operates the air compressor periodically, as needed, to maintain the air pressure at the predetermined level. Such operation may be under the control of a sensor which responds to the air pressure prevailing in the accumulator 48.

Operation of the valve 49 is controlled by an externally located, user-operable switch 50 and an internally located chlorine detector 52.

Referring now to Figure 4, the coupling device 44 interconnects the torque tube 38 (via universal coupling component 42) and the shaft section 41. The coupling device 44 is in the form of a clutch type arrangement comprising a pair of toothed clutch members 54, 56. The clutch member 54 is secured to one end of the torque tube 38 via component 42 and is slidably mounted on an extension 58 of shaft section 41. Clutch member 54 is also free to rotate with respect to the extension 58.

The other clutch member 56 is also slidably mounted on the extension 58 but is keyed against rotation by key 60 received in a keyway in the extension 58. A coil spring 62 is trapped between the two clutch members 54, 56 and serves to bias them apart. At its extremity, the extension 58 has a collar 64 which is secured to it by pin 65 and abuts the clutch member 54 so as to limit the extent to which the torque tube 38 and the shaft section 52 can be separated from one another.

An adjustable sleeve 66 is mounted on a screw threaded part 67 of the extension 58, the sleeve 66 having a complementary thread so that by rotation of the sleeve, it can be adjusted along the extension and thereby move the clutch member 56 towards the clutch member 54 or allow it to move away from the latter under the action of the spring 62. The external periphery of the sleeve 66 may be knurled or otherwise formed so as to facilitate turning thereof manually. The confronting faces of the clutch members 54, 56 are each formed with a toothed profile such that the toothed projections 68 of each member are aligned with the intertooth spaces 70 of the other member.The sleeve 66 can be adjusted to bring the toothed profiles of the two members 54, 56 into interengaged relation so that rotary drive can be transmitted from the shaft section 41 to the torque tube 38 and hence to the handwheel 30.

In use, after the outlets 16 of the valves 14 have been connected into the supply circuit, the handwheels are operated to open the valves 14. The valve operating mechanisms are then assembled to the handwheels 30. Initially, the sleeves 66 are positioned as shown in Figure 4 so that the clutch members 54, 56 are separated and thereby each permit some degree of axial play between the torque tube 38 and the shaft section 41. The connector 28 is then assembled to the handwheel with its prongs inserted into the openings 32 and the sleeve 66 is adjusted to fully engage the clutch members 54, 56 with one another. In this condition, there is substantially no axial play between the shaft extension 41 and the torque tube 38.

In normal use the valves 14 are maintained open.

If however, a leakage is detected either by an operative (who will press switch 50) and/or by the detector 52, the system operates to rotate the handwheels 30 and close the valves 14. In other words, in these circumstances, the valve 49 is opened so that the air motors are operated to rotate the shaft assemblies, via the coupling devices 44, in the valve closing direction.

The accumulator 48 is designed and arranged so that there is sufficient pressure available at all times to operate the air motors to the extent necessary to effect complete closure of all of the drum valves. In practice, without the coupling device, it is found that the wind up in the system resulting from the valve closure operation poses subsequent difficulties in releasing the torque tube from the handwheel, ie. because of the self-locking effect of the gear drive 43. However, the inclusion of the coupling device 44 eliminates this problem since the sleeve 66 can be backed off to introduce axial play into the system and allow the clutch members to be readily separated, which in turn allows the torque tube to be released from the handwheel and the handwheel operated to re-open the valve.

Although as described above, the valves 12 are described as being permanently closed, it will be appreciated that the shut-down system can be readily used with valves 12 instead of valves 14. If liquid and gaseous chlorine is to be tapped off from the drums at the same time, the system can be modified in a routine manner to cater for this requirement by fitting each valve 12, 14 with its own remote closure arrangement.

Claims (9)

1. A valve operating mechanism comprising a connector adapted to be fitted to thd handwheel of a storage vessel in drive transmitting relation with the handwheel, a rotary drive source and a shaft assembly connecting the drive source to the connector, the shaft assembly being in two parts interconnected by a coupling device which, in a first mode of operation, serves to transmit rotary drive between the two shaft parts and, in a second mode of operation, interconnects the shaft parts with axial play to allow them to be decoupled with respect to rotary drive.

2. A mechanism as claimed in Claim 1 in which the coupling device comprises a pair of clutch members, each rotatably fast with respective ones of the shaft parts and being movable relative to one another between an engaged position and a decoupled position.

3. A mechanism as claimed in Claim 1 or 2 in which the drive source is a fluid powered motor which is supplied with fluid under pressure via a receiver or accumulator.

4. A mechanism as claimed in Claim 3 including means for maintaining the fluid in the receiver or accumulator at a predetermined pressure sufficient to rotate the shaft assembly through as many revolutions as necessary to drive the handwheel from an open position to a fully closed position in the event that valve closure is required.

5. A mechanism as claimed in any one of Claims 1 to 4 in which the handwheel includes two or more openings and the connector comprises two or more projections for reception in these openings such that the projections can be inserted into and withdrawn from the handwheel in an axial direction.

6. A mechanism as claimed in any one of Claims 1 to 5 in which operation of the mechanism to effect valve closure is triggered in response to actuation of a user-operable switch located remotely from the storage vessels and/or a detector sensitive to the fluid stored by the vessel.

7. An installation comprising an enclosure, a plurality of drums mounted side by side within the enclosure with their axes generally horizontal, each drum having a valve located at one end thereof and being provided with a handwheel for opening and closing the valve, a plurality of valve operating mechanisms each as claimed in any one of Claims 1-6 associated one with each drum, and means for actuating said mechanisms to effect closure of said valves.

8. An installation as claimed in Claim 7 in which the actuating means comprises a user-operable member located externally of the enclosure.

9. An installation as claimed in Claim 7 in which the actuating means comprises a sensor arranged to monitor the atmosphere within the enclosure for the presence of gas/vapour stored by the drums.