GB2307292A - Vapour containment valve - Google Patents

Abstract

A vapour containment valve cartridge 7 comprises a cartridge housing 12 for mounting within a valve housing and having an inlet, an outlet and a valve surface arranged between the inlet and the outlet and forming a portion of a generally spherical surface 18. A valve body 28 is received within the cartridge housing 12 and has an enlargement 31 forming part of a generally spherical surface of generally equal curvature to the generally spherical surface 18 on the cartridge housing 12. A resilient O-ring seal 34 is accommodated in a groove 36 on enlargement 31 such that the weight of the valve body 28 causes sealing between the two generally spherical surfaces. As a result, vapour in the valve housing 12 below a threshold pressure is prevented from passing from the inlet to the outlet, and vapour above the threshold passes from the inlet to the outlet.

Description

VAPOUR CONTAINMENT VALVE The present invention relates to a vapour containment valve and relates particularly, but not exclusively, to a vapour containment valve for use in the petroleum and / or chemical industries.

Pressure / vacuum valves are known in the petroleum industry. The valves are used to control emission of petroleum vapours from storage systems and / or delivery points, and are generally fitted end of line on a system to vent vapours above a certain pressure to the atmosphere, or as part of a larger system, for example for vapour recovery. In the United Kingdom, because petrol storage facilities are not recognised as pressure vessels, current guidelines only allow a pressure of 0.5psi to be instilled upon such facilities. The valves retain petroleum vapour within the storage system until the valve working pressure is reached, after which the valve vents to atmosphere to release the pressure build-up. Once the pressure within the storage system has been reduced, the cycle of pressure build-up starts again.

Existing valves suffer from the disadvantage of requiring regular checks to ensure that they are operating within specified tolerances due to the method of their manufacture, for example spring controlled or lever controlled valves.

Existing valves are also susceptible to either sticking or leakage if fitted at an angle other than vertical, which can have an adverse effect on the operating efficiency of such valves.

According to an aspect of the present invention, there is provided a vapour containment valve cartridge, the cartridge comprising: a first valve member for mounting within a valve housing and having an inlet, an outlet and a first valve surface arranged between said inlet and said outlet, the first valve surface forming a portion of a first substantially spherical surface; a second valve member adapted to be received in said first valve member and having a second valve surface for contact with said first valve surface, said second valve surface forming a portion of a second substantially spherical surface of substantially equal curvature to said first substantially spherical surface; and sealing means for sealing between said first and second valve surfaces by means of the weight of said second valve member, wherein vapour in the valve housing below a threshold pressure is prevented from passing from said inlet to said outlet, and vapour above said threshold pressure passes from said inlet to said outlet.

By providing first and second valve surfaces in the form of portions of substantially spherical surfaces, the sealing action of the valve cartridge is not significantly impaired by non-vertical alignment of the valve cartridge in use in the valve housing.

The sealing means may comprise an O-ring of resilient material located in a groove formed in said second valve surface.

This provides the advantage that by suitable location of the groove, the sealing surface area, and therefore the threshold pressure of the valve, can be adjusted.

The first and second valve members are preferably provided with co-operating guide means for controlling relative movement of the first and second valve members.

In a preferred embodiment, said co-operating guide means comprises upper and lower stems on said second valve member for sliding movement within corresponding apertures in said first valve member.

At least one said aperture may be formed within a removable part of the first valve member.

This provides the advantage of facilitating access to the second valve member for removal and / or replacement and / or maintenance thereof.

The cartridge preferably further comprises resilient means for preventing collision between the first and second valve members when the pressure in the valve housing exceeds the threshold pressure.

This provides the advantage of reducing undesirable noise caused by collision between the first and second valve members when vapour is vented through the valve cartridge.

In a preferred embodiment, the resilient means comprises an O-ring arranged between opposing faces of the first and second valve members.

The cartridge may further comprise external sealing means for effecting sealing between the exterior of the first valve member and the interior of the valve housing.

In a preferred embodiment, the external sealing means comprises at least one O-ring of resilient material arranged in a respective groove in the external periphery of the first valve member.

This provides the advantage of allowing for differing expansion and contraction co-efficients of the first valve member and internal wall of the valve housing.

According to another aspect of the invention, there is provided a vapour containment valve assembly, the assembly comprising a valve cartridge as defined above, and a valve housing for receiving the valve cartridge.

In a preferred embodiment, the valve housing is provided with at least one aperture for receiving a locking member for locking the second valve member in the sealing condition thereof relative to the first valve member.

This provides the advantage of enabling a system in which the valve assembly is installed to be pressure tested, for example to locate leaks in other parts of the system, while the valve assembly remains installed in the system.

The valve assembly may further comprise an air inlet valve for allowing air to enter the valve housing in response to pressure reduction therein.

This provides advantages when the valve assembly is installed in a petroleum storage system, such as a filling station, since problems caused by pressure reduction in the system as a result of removal of petroleum to a customer's vehicle can be prevented by inlet of air into the system.

The valve assembly may further comprise an adaptor for connection to the valve housing adjacent said outlet, wherein said adaptor is connected in use to pipework.

This provides the advantage of enabling the valve assembly to be connected in line, as opposed to end of line.

According to a further aspect of the invention, there is provided a volatile fluid storage system comprising a valve assembly as defined above, and a storage vessel having a vapour outlet connected to the valve assembly adjacent said inlet.

According to a further aspect of the invention, there is provided a volatile fluid delivery method, the method comprising the steps of: delivering volatile fluid from an outlet of a volatile fluid delivery vehicle to a storage vessel of the system as defined above; and delivering vapour passing through the outlet of the valve cartridge to an inlet of the delivery vehicle.

This provides the advantage of minimising pollution caused by escape of vapour to the atmosphere, while vapour below the threshold pressure of the valve cartridge is retained within the storage system, thus minimising waste.

The method may further comprise the step of supplying fluid to a plurality of said storage vessels wherein the outlets of said assemblies are connected to a single vehicle.

A volatile fluid may be petroleum.

In order that the invention may be better understood, a preferred embodiment of the invention is described in detail below, by way of example only, and not in any limitative sense, with reference to the accompanying drawings in which: Figure 1 is a schematic view of a valve assembly embodying an aspect of the present invention; Figure la is a vertical cross-sectional view of an adapter of the assembly of Figure 1; Figure ib is a vertical cross-sectional view of a clamp ring of the assembly of Figure 1; Figure 2a is a vertical partial cross-sectional view of part of a valve cartridge of Figure 1; Figure 2b is a vertical cross-sectional view of a valve body of Figure 2a; Figure 2c (i) is a vertical cross-section of part of a cartridge housing of Figure 2a; Figure 2c (ii) is a view from below of the cartridge housing of Figure 2c (i);; Figure 2d (i) is a plan view of a guide ring of the valve cartridge housing of Figure 2a; Figure 2d (ii) is a cross-sectional view of the guide ring of Figure 2d (i); Figure 3 is a view of a locking bar for use in testing the valve assembly of Figure 1; Figure 3a (i) and Figure 3a (ii) show removable plugs for use with the valve assembly of Figure 1; Figure 3b is a partial cross-sectional elevation of part of the valve assembly of Figure 1 with the locking bar of Figure 3 in place; Figure 4 is a partial cross-section elevational view of a lower part of the valve assembly of Figure 1; Figure 4a (i) is a plan view of a guide ring of the assembly shown in Figure 4; Figure 4a (ii) is a cross-section of the guide ring shown in Figure 4a (i); Figure 4b (i) is a plan view of a valve seat of Figure 4; Figure 4b (ii) is a cross-section of the valve seat of Figure 4b (i); and Figure 4c is a cross-sectional view of a vacuum valve poppet of Figure 4.

Referring in detail to Figure 1, a valve assembly 1 comprises a valve housing in the form of an aluminium main body 2 having a threaded top aperture 3 for receiving a threaded adapter 4, a threaded bottom aperture 5 for mounting to a pipe (not shown) connected to the upper part of a petroleum storage vessel, and a non-threaded air inlet aperture 6 open to the atmosphere.

Adapter 4 (the function of which will be described in greater detail below) enables top aperture 3 to be connected to an inlet pipe of a petroleum delivery tanker (not shown), and upper aperture has 2 inch BSP (British Standard Pipe) taper.

Similarly, bottom aperture 5 has 2.5 inch BSP taper to accept reducing bushes to enable connection of main body 2 to pipes of smaller diameter, and air inlet aperture 6 is arranged at the same height as bottom aperture 5 and is non-threaded. Aperture 3, 5, 6 have generally the same diameter.

A pressure cartridge assembly 7, which will be described in greater detail below, is accommodated within main body 2 and a clamp ring 8 is arranged on top of the pressure cartridge 7.

The clamp ring 8 is held in place underneath a spark arrestor 9 in the form of a 60 / 60 stainless steel gauze by means of adapter 4 which has an external thread for fitting in aperture 3.

Valve body 2 is also provided with a pair of generally diametrically opposite apertures 10, one of the apertures 10 being arranged slightly higher than the other, the purpose of which will be described in greater detail below. During normal use of the valve assembly 1, apertures 10 are plugged and sealed (see Figure 3a). An adapter port 11 allows the insertion of a test needle (not shown) to monitor pressures within the valve system 1 without allowing vapours to escape.

Referring now to Figures 2a to 2c, the pressure cartridge 7 comprises a first valve member in the form of a cartridge housing 12 machined from gunmetal or any other suitable material and of generally cylindrical external shape and of external diameter slightly less than the internal diameter of the adjacent part of main body 2 to which the pressure cartridge 7 is mounted. The external surface of the cartridge housing 12 is provided with a pair of grooves 13 for receiving O-rings 14 (see Figure 3b) of suitable resilient material such as nitrile or viton for sealing between the cartridge housing 12 and the main body 2. O-rings 14 form an air tight seal between cartridge housing 12 and the adjacent part of main body 2 and also allow for differing expansion and contraction coefficients of those components.

The cartridge housing 12 has a bottom guide member 15 formed therein and defining a plurality of vapour inlet spaces 16 and having a generally circular central aperture 17 therethrough above the bottom guide member 15. An internal valve surface 18 forms a portion of a generally spherical surface, and a generally cylindrical region 19 extends above the internal valve surface 18 to a shoulder 20 for receiving a removable upper guide member 21. The upper guide member 21 is held in place by means of a circlip 22 received in a groove 23 above the upper guide member 21.

As shown in Figure 2d, upper guide 21 comprises a stamped outer ring 24 of brass or any suitable material to which a concentric inner ring 25 having a generally circular central aperture 26 therethrough is attached by three generally equiangularly arranged spacers 27 such that aperture 26 of upper guide 21 is axially aligned with aperture 17 of lower guide member 15.

Referring again to Figure 2a, a second valve member in the form of a valve body 28 of brass has an upper generally cylindrical guide portion 29 having an external diameter slightly smaller than the internal diameter of aperture 26 of upper guide member 21, and a lower generally cylindrical guide portion 30 having external diameter slightly less than the internal diameter of aperture 17 of lower guide member 15 and aligned with guide portion 29.

Between the upper 29 and lower 30 guide portions an enlargement 31 has an external valve surface 32 forming part of a generally spherical surface of substantially the same curvature as the spherical surface formed by internal valve surface 18 of cartridge housing 12. The external valve surface 32 is provided with a groove 33 for accommodating a resilient O-ring seal 34, and a shoulder portion 35 is arranged at the upper part of enlargement 31 and has a groove 36 at the radially inner most part thereof for accommodating an O-ring 37. The O-ring 37 serves to prevent metal to metal contact between shoulder portion 35 and upper guide 21 as the valve body 28 slides within the cartridge housing 12, and thus reduces unwanted noise as vapour is vented through the valve cartridge 7.

Referring to Figure lb, clamp ring 8 comprises a gun metal, machined ring having a pair of generally diametrically opposite slots 38, of which only one is shown in Figure lb.

The external diameter of clamp ring 8 is slightly less than the internal diameter of the adjacent part of main body 2, such that clamp ring 8 when resting on cartridge housing 12 extends upwards in the pipe as far as shoulder 39 thereof (see Figure 3b).

As shown in greater detail in Figure la, adapter 4 is gravity diecast and has generally circular cross-section. The adapter 4 is provided with an external thread 40 for fitting to a corresponding thread in aperture 3, and an internal thread 41 for receiving a pipe (not shown) fitted thereto. A seal is formed between adapter 4 and main body 2 by means of a resilient O-ring 42 arranged within groove 43 in the external periphery of adapter 4. The adapter 4 serves the dual purpose of allowing pipes of varying diameter to be attached to the top of the main body, as well as preventing damage to the internal thread of main body 2 during pipe installation.

Pressure cartridge 7 is held in place inside main body 2 by being placed inside the main body 2 through aperture 3 when adapter 4 is removed until lower guide member 15 of cartridge housing 12 rests upon a circumferential stop 44 (see Figure 3b) arranged at the internal periphery of main body 2. Clamp ring 8 is then placed on top of cartridge housing 12 with slots 38 thereof aligned with apertures 10 of main body 2, and the spark arrestor 9 is placed on top of the clamp ring 8 such that the external periphery of the spark arrestor 9 rests on shoulder 39 of the main body. The entire assembly is then held in place when adapter 4 is screwed into aperture 3.

As shown in Figures 3 and 3b, a locking bar 45 comprises a steel bar having a narrow end 46, intermediate portion 47 and a wide end 48. When the locking bar 45 is inserted through apertures 10 in main body 2 and slots 38 in clamp ring 8, engagement of sloping face 49 of intermediate portion 47 presses valve body 28 downwards relative to the cartridge housing 12 to maintain the valve in the closed position (i.e.

the O-ring 34 compressed between valve surfaces 18 ,32). This arrangement can be used to pressure test a storage system such as a petroleum or chemical storage system in which the valve assembly 1 is installed, e.g. to determine whether leaks occur in other parts of the system, such as in storage tanks, suction lines, vent lines or the like, without necessitating removal of the valve cartridge 7 from the main body 2.

When pressure testing is not being carried out, apertures 10 are normally closed by means of plugs 50 as shown in Figures 3a (i) and (ii) and which comprise threaded brass bolts having resilient O-rings 51.

Referring to Figure 4, an air inlet valve cartridge 52 is provided in aperture 6 of main body 2. The air inlet valve cartridge allows air to enter the vacuum side of valve system 1 when installed in a petroleum storage and delivery facility such as a filling station when pressure at the vacuum side of the system 1 decreases as suction lines draw petrol from storage tanks (not shown) to a delivery point. When petrol is not being drawn to a delivery point, the air inlet valve cartridge 52 remains closed.

As shown in greater detail with reference to Figures 4a to 4c, inlet valve cartridge 52 comprises a brass stamped valve poppet 53 having a stem 54 and a base 55. Base 55 has a rebate 56 for accommodating an O-ring seal 57. Poppet 53 is arranged such that its stem 54 extends vertically upwards and slides within a central aperture 58 of valve ring 59 between an upper open position and lower closed position in which base 55 rests on valve seat 60 such that sealing by O-ring 57 occurs between the base 55 and the valve seat 60. The weight of valve poppet 53 is such that the vacuum valve allows inlet of air at approximately 0.8psi. The vacuum valve cartridge 52 also contains a filter medium and gauze 61, and the assembly is held in place by means of a pair of circlips 62. The gauze is in the form of a 50mm x 50mm mesh, or a pair of meshes between which the air filter medium is retained.The air filter reduces the amount of dirt and dust entering the vacuum valve cartridge 52 which may otherwise cause the valve to leak or stick.

The operation of the valve system 1 shown in the drawings will now be described. In the particular embodiment described, a plurality of valve systems 1 are provided at a petrol storage location such as a filling station, the storage location having a plurality of storage tanks, to a vapour outlet part of each of which the aperture 5 of a respective valve system 1 is connected.

When a delivery of petroleum is made to the petroleum storage location, an outlet of a petroleum delivery vehicle such as a tanker (not shown) is connected to an inlet pipe of one or more petroleum storage tanks of the storage location.

At the same time, aperture 3 of each valve system 1 is connected via pipework to a single inlet pipe of the petroleum delivery vehicle.

As the petroleum storage tank at the storage location (not shown) is filled with liquid petroleum, petroleum vapour 5 is forced out of the tank and enters main body 2 through aperture 5 where it enters inlets 16 of lower guide 15 of cartridge housing 12, but cannot pass upwards to aperture 3 because of the sealing action between valve body 28 and cartridge housing 12, and between cartridge housing 12 and the internal wall of the main body 2 around the housing 12. Vapour is retained within the system by sealing action under the weight of valve body 28 until the pressure of the vapour becomes sufficiently high that the weight of valve body 28 can be overcome to allow vapour to pass between internal valve surface 18 and O-ring 34 to pass upwards through upper guide 21 and aperture 3 to be returned to the petroleum delivery vehicle (not shown).When the pressure reduces in the system as a result of vapour being vented through cartridge assembly 7, the weight of valve body 28 is sufficient to ensure that sealing occurs between O-ring 28 and internal valve surface 18.

At this time, the pressure inside each main body 2 is sufficiently high that valve poppet 53 is forced down onto valve seats 60 to compress O-ring 57, such that the inlet valve cartridge 52 remains in the closed position.

It can therefore be seen that as petroleum is delivered to the storage location, petroleum vapour forced out of the storage tanks is simultaneously returned to the storage vehicle, and polluting escape of vapour to the atmosphere is prevented. In addition, a substantial proportion of the petroleum vapour is retained within the storage location, and only vapour exceeding the threshold pressure of valve cartridge 7 escapes through aperture 3 to be returned to the delivery vehicle, thus minimising waste.

Subsequently to delivery, the pipework connecting aperture 3 of each valve system to the delivery vehicle is sealed off by means of a suitable cap (not shown). As suction lines draw petrol from the storage tanks to a delivery point such as a customer's vehicle, this causes a vacuum (i.e.

pressure reduction) which in turn causes vacuum cartridge 52 to open, allowing air to enter the main body 2 through aperture 6.

This arrests the formation of any vacuum which could hinder operation or damage the storage system.

It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only, and not in any limitative sense, and that various alterations and modifications of the invention are possible without departure from the scope of the invention as defined by the appended claims. For example, different materials may be used depending upon the nature of the fluid to be retained within the system, for example to reduce the instance of chemical attack of constituent parts of the system by fluids retained therein.

Claims (21)

CLAIMS:

1. A vapour containment valve cartridge, the cartridge comprising: a first valve member for mounting within a valve housing and having an inlet, an outlet and a first valve surface arranged between said inlet and said outlet, the first valve surface forming a portion of a first substantially spherical surface; a second valve member adapted to be received in said first valve member and having a second valve surface for contact with said first valve surface, said second valve surface forming a portion of a second substantially spherical surface of substantially equal curvature to said first substantially spherical surface; and sealing means for sealing between said first and second valve surfaces by means of the weight of said second valve member, wherein vapour in the valve housing below a threshold pressure is prevented from passing from said inlet to said outlet, and vapour above said threshold pressure passes from said inlet to said outlet.

2. A cartridge according to claim 1, wherein the sealing means comprises an O-ring of resilient material located in a groove formed in said second valve surface.

3. A cartridge according to claim 1 or 2, wherein the first and second valve members are provided with co-operating guide means for controlling relative movement of the first and second valve members.

4. A cartridge according to claim 3, wherein said cooperating guide means comprises upper and lower stems on said second valve member for sliding movement within corresponding apertures in said first valve member.

5. A cartridge according to claim 4, wherein at least one said aperture is formed within a removable part of the valve member.

6. A cartridge according to any one of the preceding claims, further comprising resilient means for preventing collision between the first and second valve members when the pressure in the valve housing exceeds the threshold pressure.

7. A cartridge according to claim 6, wherein said resilient means comprises an O-ring arranged between opposing faces of said first and second valve members.

8. A cartridge according to any one of the preceding claims, further comprising external sealing means for effecting sealing between the exterior of the first valve member and the interior of the valve housing.

9. A cartridge according to claim 8, wherein said external sealing means comprises at least one O-ring of resilient material arranged in a respective groove in the external periphery of the first valve member.

10. A vapour containment valve assembly, the assembly comprising, a valve cartridge according to any one of the preceding claims, and a valve housing for receiving the valve cartridge.

11. A valve assembly according to claim 10, wherein the valve housing is provided with at least one aperture for receiving a locking member for locking the second valve member in the sealing condition thereof relative to the first valve member.

12. A valve assembly according to claim 10 or 11, further comprising an air inlet valve for allowing air to enter the valve housing in response to pressure reduction therein.

13. A valve assembly according to any one of claims 10 to 12, further comprising an adaptor for connection to the valve housing adjacent said outlet, wherein said adaptor is connected to use in pipework.

14. A volatile fluid storage system comprising a valve assembly according to any one of claims 10 to 13, and a storage vessel having a vapour outlet connected to the valve assembly adjacent said inlet.

15. A volatile fluid delivery method, the method comprising the steps of:- delivering volatile fluid from an outlet of a volatile fluid delivery vehicle to a storage vessel of a system according to claim 14; and delivering vapour passing through the outlet of the valve cartridge to an inlet of the delivery vehicle.

16. A method according to claim 15, further comprising the step of supplying fluid to a plurality of said storage vessels wherein the outlets of said assemblies are connected to a single vehicle.

17. A method according to claim 15 or 16, wherein the volatile fluid is petroleum.

18. A vapour containment valve cartridge substantially as hereinbefore described with reference to the accompanying drawings.

19. A vapour containment valve assembly substantially as hereinbefore described with reference to the accompanying drawings.

20. A volatile fluid storage system substantially as hereinbefore described with reference to the accompanying drawings.

21. A volatile fluid delivery method substantially as hereinbefore described with reference to the accompanying drawings.