GB2382399A

GB2382399A - A valve actuating device,valve and method

Info

Publication number: GB2382399A
Application number: GB0206683A
Authority: GB
Inventors: Grahame Harcourt Platt
Original assignee: ENVIROTECH PRODUCTS Ltd
Current assignee: ENVIROTECH PRODUCTS Ltd
Priority date: 2002-03-21
Filing date: 2002-03-21
Publication date: 2003-05-28
Also published as: GB0206683D0; AU2003216824A1; WO2003081102A1

Abstract

In a combined roll over and pressure/ vacuum relief valve 10 and an actuation device 100, the valve comprises a valve body 18, 20 and a roll-over gravity element 52, 58 pivoted in the valve body and which actuates the valve when the orientation of the valve body changes with respect to gravity. The actuation device comprises a valve body engagement member 102 and a rollover gravity element engagement part 104. The actuation device has two positions. In the first the engagement part 104 and member 102 can engage said element 58 and body 20 respectively. In a second position, the element 58 is displaced by part 104 to actuate the valve and close it. A catch 72 on the device releasably retains the part 104 in engagement with the element 58 in the second position. In a second embodiment the actuation device comprises a lever acted on by a weight and has only one position in which the element 58 is displaced. The device may be used when testing a tank in which the valve and fire engulfment valve are fitted to test seals and operability of the valve.

Description

Valve Actuating Device, Valve and Method This invention relates to volatile fuel storage tanks and pressure/vacuum relief valves therefor. In particular, this invention relates to transportable tanks wherein said valve incorporates a rollover shut-off mechanism. More particularly, the invention relates to a valve actuating device for testing such valves, and to a method of testing transportable volatile fuel storage tanks incorporating such valves.

Pressure/vacuum relief valves are known that pop open when a given pressure difference on either side of the valve is exceeded. This can occur when temperatures rise or when the liquid, typically hydrocarbon fuel, is agitated-such as tends to occur during transport.

Pressures can also rise during filling. On the other hand, during drainage of the liquid (or indeed, after cooling or settling of the liquid) a vacuum situation can pertain in the tank. Then ambient air should be permitted to enter the tank to relieve the vacuum.

It is also known to provide a rollover mechanism for such valves that automatically closes the valve in the event that the tank is toppled. This is necessary because the action of rolling over will always result in the pressure difference mentioned above being exceeded and the pressure relief valve opening. That can lead to loss of fuel.

Finally, a fire engulfment valve is disposed in the tank to open when the pressure difference across the valve exceeds a higher threshold pressure. Normally, this valve is not operated because the pressure/vacuum relief valve will operate first. However, in a rollover

situation the pressure relief valve will be closed by the rollover mechanism. However, should a fire, for example, outside the tank cause excessive heating of the liquid therein, this could result in catastrophic rupture of the tank. Thus a fire engulfment valve is arranged to open first. In this event there is a controlled escape of pressurised liquid/vapour which, although undesirable in itself, is clearly the lesser of two evils.

New British Standard BS EN 12972/2001 requires regular testing of tanks and the aforementioned valves, as well as of the integrity of the seals between such valves and the wall of the tanks.

It is an object of the present invention to provide a device that facilitates such testing. The present invention is predicated on the fact that pressure/vacuum relief valves are almost invariably disposed adjacent inspection hatches formed in the top walls of tanks. It is also predicated on the fact such valves almost invariably are contained primarily within the confines of the tank, and particularly the rollover mechanism, and where access is, therefore, impossible from outside the tank.

In accordance with a first aspect of the present invention, there is provided a rollover pressure/vacuum relief valve and an actuation device therefor, wherein the valve comprises a valve body and a rollover gravity element pivoted in the valve body and which actuates the valve when the orientation of the valve body changes with respect to gravity, said actuation device comprising a valve body engagement member and a rollover gravity element engagement part, said part being mounted on the member, and wherein the device has two positions, in a

first of which positions said part and member can engage said element and body respectively and in a second of which positions said element is displaced by said part and with respect to the body to actuate the valve, a catch on the device releasably retaining the device in engagement with the valve in said second position.

Preferably, said gravity element part of the device is displaceably mounted on the body member of the device, said positions of the device being dispositions of said part with respect to said member.

Preferably, said part is spring biased with respect to the member towards said second position.

Preferably, said catch is formed on said part.

Said valve body may comprise a skirt and said gravity element may comprise a pendulum having a lip. In this event, when engaged between said skirt and lip, said part and member are urged apart by said spring bias to displace the pendulum into said actuated position of the valve. Said gravity element part may be slidably mounted on studs, springs on said studs urging the gravity element part and body member apart. The body member may have a fork adapted to fit over said skirt to locate the body member and gravity element with respect to the pendulum.

Alternatively, said actuation device may comprise a gravity lever which, when engaged between said skirt and lip, levers the pendulum into an actuated position of the valve by action of gravity on the lever when the valve is in a normal operational position in which the pendulum would not otherwise actuate the valve. In this event,

said member and parts are regions of the lever. Said catch may be a step in the lever.

In a second aspect, the present invention provides a rollover pressure/relief valve actuation device comprising a valve body engagement member, a rollover gravity element engagement part, mounted on said member, bias on the device to urge the rollover gravity element of a rollover pressure/vacuum relief valve into an actuated position thereof when said element part and body member are engaged with said gravity element and valve body respectively and said valve body is in a normal operational position in which said gravity element would not otherwise actuate the valve, and a catch to retain the device in position on the valve.

Preferably, said element part is displaceably mounted on the body member and said bias comprises a spring disposed between them.

In a third aspect, the present invention relates to a method of testing a transportable volatile fuel tank comprising: a) a tank; b) an inspection aperture; c) a closure for said aperture; d) a rollover pressure/vacuum relief valve having a valve body and a gravity element adapted to close the valve in the event of displacement of the tank from a normal operational position; and e) a fire engulfment valve, said method comprising the steps of: i) opening said aperture; ii) manually activating said gravity element to close said relief valve; and

iii) pressurising said tank to detect any leakage through said relief valve and fire engulfment valve, and any other part of the tank, and to detect the pressure at which said engulfment valve actuates.

Potentially, it is possible, before step i) above, to take the steps of: iv) closing said aperture v) pressurising said tank to detect any leakage through said pressure/vacuum valve and any other part of the tank; and vi) further pressurising said tank to detect the pressure at which said pressure/vacuum relief valve operates to relieve said pressure.

Alternatively, however, it is possible to test the fluid-tightness and operability of the pressure/vacuum relief valve from outside the tank by connecting a chamber to the outlet of the valve and, firstly, applying a reduced pressure to the chamber to test the seal, and noting the pressure at which the pressure relief valve pops, and secondly to pressurise the chamber and note the pressure at which the vacuum relief valve operates. This avoids the need to pressurise the entire tank twice.

Preferably, said manual activation of said gravity element is effected by use of an actuation device in accordance with this invention.

Preferably, said device is inserted through said aperture prior to engagement with said relief valve.

The invention is further described hereinafter, by way of example, with reference to the accompanying

drawings, in which: Figure 1 is a section through a rollover pressure/vacuum relief valve, held in an actuation position by an actuation device in accordance with the present invention; Figure 2 is a similar view to Figure 1 but with a different embodiment of actuation device; Figure 3 is a schematic illustration of a tank to which the present invention has effect; and Figure 4 is a side section through the actuation device shown in Figure 1.

With reference to Figure 1, a rollover pressure/vacuum relief valve 10 is shown. This has a shoulder 12, an 0-ring seal 14, and a threaded neck 16.

The neck 16 is arranged for insertion through a hole in a top wall of a tank (not shown in Figure 1) and to be secured therein by a threaded nut (also not shown). The bulk of the valve 10 is therefore within the confines of the tank.

The valve 10 comprises a hollow valve body 18 terminating in a skirt 20. A plunger 22 has magnet elements 24 seated on a ferromagnetic ring 26 fixed in the valve body 18. An 0-ring seal 28 seals the plunger 22 against the ferromagnetic ring and hence against the valve body 18. Should the pressure in the valve body exceed a low threshold limit (about 100 mBar) then the magnetic attraction between the magnet elements 24 and ferromagnetic ring 26 is broken and the plunger 22 pops up permitting venting of the tank around the plunger 22 through passages 30 in the plunger 22.

In the event of a vacuum developing in the tank, a vacuum seal element 32 is provided in the plunger 22.

The seal element 32 has an 0-ring 34 to seal against a seat 36 in the plunger. A spring 38 urges the seal element against seat 36. The springs 38 are supported on a circlip 40 supported on downwardly depending legs 42 of the plunger 22.

A rollover mechanism 50 comprises a pendulum 52 pivotably mounted in a plate couplet 54 with two degrees of freedom of rotation (in fact, it has a third degree of freedom of rotation about the axis 52. However, this has no relevance). A plate 56 is mounted on the pendulum 52 and, when gravity deflects a weight 58, the pendulum 52 pivots in the couplet 54 and tilts the plate 56. A seal element 60 is spring biased out of engagement with a seat 62 in the valve body 18 by a spring 64. An 0-ring 66 on the valve member 60 affects a seal against the seat 62 when the plate 56 is tilted as shown in Figure 1.

Thus, when a tank incorporating the pressure/vacuum relief valve 10 in a horizontal top wall is tilted from its normal operational position through an angle a equal to about 20 degrees, the seal member 60 is pressed against seat 62 closing the valve 10.

Also shown in Figure 1 is a valve actuation device 100 in accordance with the present invention. The actuation device 100 comprises a body member 102 and a gravity element 104. The gravity element 104 is mounted through studs 106 and dowels 108 and urged apart by springs 110 (see also Figure 4). Thus, the gravity element 104 is movable back and forth in the direction of the arrow X is Figure 1 relative to the body member 102.

The body member 102 is provided with a fork 112 adapted to engage anywhere around the periphery of skirt

20 of the valve 10. Before the fork 112 can be engaged with the skirt 20, the pendulum 52 must be displaced slightly in order to permit access of the fork to the inside of skirt 20. During insertion, the gravity element 104 is pressed against the body member 102, compressing the springs 110. When the fork 112 is fully inserted around skirt 20, ledge or rim 70 of weight 58 can engage catch 72 on gravity element 104. When gravity element 104 is released, springs 110 push it leftwardly in the drawing and displace the pendulum 52 sufficiently far to tilt plate 56. Seal member 60 compresses spring 64 and gently seats 0-ring 66 against seat 62. Indeed, the strength of the springs 110 are selected so that the valve formed by valve member 60 only just closes.

In the position shown in Figure 1, the actuation device 100 is retained in engagement with the valve 10 by the catch 72. It can only be released therefrom by compressing the gravity element against the body member so that catch 72 can escape from edge 70, and the fork 112 be withdrawn from engagement with the skirt 20.

Referring to Figure 2, a different embodiment of actuation device 100'is shown. Here, the actuation device 100'comprises a simple lever comprising a body member 102'and a gravity element 104'in which a catch 72'is formed. In this embodiment there is no relative movement between body member 102'and gravity element

104'. Instead, to employ the device 100', the body member 102 is inserted between weight 58 of the pendulum 52 and skirt 20. The lever 100'is then pivoted downwardly (in Figure 2) pushing the weight 58 leftwardly in the drawing until the catch 72 engages with the lip 70 of the weight 58. At this point, the lever 100'can be released and a weight 112 on its end constitutes a bias

and serves to pivot the lever 100 about catch 72.

Pivoting continues until a limit is reached defined by contact between seal member 60 and its seat 62, and contact between the body member 102'and the inside of skirt 20. Again, the magnitude of the weight 112 is arranged so that the displacement force on the pendulum 52 is not quite matched by the restoring force of the spring 64. The valve formed by member 60 and seat 62 is then only lightly closed.

Light closing represents the minimum position equivalent to perhaps only 20 degrees of tilting of the tank and it is at this degree of closing that the valve 60,62 is most likely to leak, if at all. Thereafter, increasing fluid pressure in the tank, or increased tilting should press the valve member 60 progressively more tightly against its seat 62.

Referring to Figure 3, a transportable storage tank 150 has various valves and apertures in its walls having various functions, and only some of which are schematically illustrated. An inspection aperture 152 is illustrated having an openable closure member 154. A seal 156 is provided to seal the interior of the tank 150 when the closure member 154 is closed as shown in Figure 3. Near to the inspection aperture 152 is a rollover pressure/vacuum relief valve 10, substantially as illustrated in Figures 1 and 2. A weather shield 158 is shown protecting the outlet 159 to the valve. A fire engulfment valve 160 is also shown. Finally, a filling and draining port 170 is disposed in the bottom of the tank 150.

To test the efficacy and operability of the various seals and valves, the following routine is proposed.

First, the aperture 152 is closed and the tank 150 is pressurised to a pressure approaching 100 mBar.

Evidence of any leakage is detected and faulty components replaced.

Second, the pressure inside the tank is increased and the pressure at which plunger 22 pops to relieve the pressure inside the tank 150 is noted. If this is not at the prescribed pressure, valve 10 is replaced or adjusted. (Adjustment is possible by adjusting the position of the magnetic elements 24 with respect to the plunger 22 so that they are nearer or further from the ferromagnetic ring 26).

Alternatively, the aforementioned features can be tested by applying a vacuum chamber on outlet 159 (after removing weather shield 158) and reducing the pressure therein to detect both leakage past the pressure relief valve plunger 22 and the pressure at which it pops.

Hitherto, it has not been possible to test in situ the rollover seal (60,66, 62), nor to test the fire engulfment valve 160. It is not possible to test that valve because pressure relief valve 10 operates to relieve pressure at a much lower pressure (about 100 mBar) than the designed opening pressure of fire engulfment valve 160 (typically about 220 mBar).

Thus, the present invention suggests opening closure member 154 and engaging actuation device 100 with the rollover pressure/vacuum relief valve 10, as described above. After engagement thereof, as shown in Figure 1 or 2, as the case may be, the closure member 154 is again closed and the tank 150 pressurised. As the pressure

increases above the normal threshold value of popping of plunger 22, the efficacy of the seal effected by the rollover mechanism 50, as well as by the fire engulfment valve 160 can be tested.

Finally, the pressure at which the fire engulfment valve 160 releases can be checked to confirm compliance.

If any leakage is detected or the threshold pressure for the fire engulfment valve 160 is inappropriate, the requisite adjustments or changes can be made.

The great advantage with the present invention is that the components are tested in situ. Hitherto, the only method of testing is to remove the components so that they can individually be checked. However, this does not test either their operability in situ or, indeed, the seal between them and the tank (seal 14 in the case of the rollover pressure/vacuum relief valve 10).

Claims

1. A rollover pressure/vacuum relief valve and an actuation device therefor, wherein the valve comprises a valve body and a rollover gravity element pivoted in the valve body and which actuates the valve when the orientation of the valve body changes with respect to gravity, said actuation device comprising a valve body engagement member and a rollover gravity element engagement part, said part being mounted on the member, and wherein the device has two positions, in a first of which positions said part and member can engage said element and body respectively and in a second of which positions said element is displaced by said part and with respect to the body to actuate the valve, a catch on the device releasably retaining the device in engagement with the valve in said second position.

2. A valve and actuation device as claimed in claim 1, wherein, said gravity element part of the device is displaceably mounted on the body member of the device, said positions of the device being dispositions of said part with respect to said member.

3. A valve and actuation device as claimed in claim 2, wherein, said part is spring biased with respect to the member towards said second position.

4. A valve and actuation device as claimed in claim 2 or 3, wherein said catch is formed on said part.

5. A valve and actuation device as claimed in any

preceding claim, wherein said valve body comprises a skirt and said gravity element comprises a pendulum having a lip.

6. A valve and actuation device as claimed in claims 3 and 5, wherein, when engaged between said skirt and lip, said part and member are urged apart by said spring bias to displace the pendulum into said actuated position of the valve.

7. A valve and actuation device as claimed in claim 6, wherein said gravity part is slidably mounted on studs, springs on said studs urging the gravity part and body member apart.

8. A valve and actuation device as claimed in claim 6 or 7, wherein the body member has a fork adapted to fit over said skirt to locate the body member and gravity element with respect to the pendulum.

9. A valve and actuation device as claimed in claim 5, wherein said actuation device comprises a gravity lever which, when engaged between said skirt and lip, levers the pendulum into an actuated position of the valve by action of gravity on the lever when the valve is in a normal operational position in which the pendulum would not otherwise actuate the valve.

10. A valve and actuation device as claimed in claim 9, wherein, said member and parts are regions of the lever, said catch being a step in the lever.

11. A rollover pressure/relief valve actuation device comprising a valve body engagement member, a

rollover gravity element engagement part, mounted on said member, bias on the device to urge the rollover gravity element of a rollover pressure/vacuum relief valve into an actuated position thereof when said element part and body member are engaged with said gravity element and valve body respectively and said valve body is in a normal operational position in which said gravity element would not otherwise actuate the valve, and a catch to retain the device in position on the valve.

12. An actuation device as claimed in claim 11, wherein, said element part is displaceably mounted on the body member and said bias comprises a spring disposed between them.

13. An actuation device as claimed in claim 11 or 12, having any of the features defined in any of claims 2 to 10.

14. A method of testing a transportable volatile fuel tank comprising: a) a tank; b) an inspection aperture; c) a closure for said aperture; d) a rollover pressure/vacuum relief valve having a valve body and a gravity element adapted to close the valve in the event of displacement of the tank from a normal operational position; and e) a fire engulfment valve, said method comprising the steps of: i) opening said aperture; ii) manually activating said gravity element to close said relief valve; and iii) pressurising said tank to detect any leakage

through said relief valve and fire engulfment valve, and any other part of the tank, and to detect the pressure at which said engulfment valve actuates.

15. A method as claimed in claim 14, wherein before step i) above, the method comprises the steps of: iv) closing said aperture v) pressurising said tank to detect any leakage through said pressure/vacuum valve and any other part of the tank; and vi) further pressurising said tank to detect the pressure at which said pressure/vacuum relief valve operates to relieve said pressure.

16. A method as claimed in claim 14 or 15, wherein said manual activation of said gravity element is effected by use of an actuation device as claimed in claim 11,12 or 13.

17. A method as claimed in claim 14,15 or 16, wherein said device is inserted through said aperture prior to engagement with said relief valve.