ZA200602663B - Footvalve - Google Patents

Description

© 2005450588

BACKGROUND TO THE INVENTION

THIS invention relates to a footvalve. In particular, the invention relates to a pneumatically operated, pressure-balanced fuel delivery footvalve for a fuel tanker.

A footvalve, sometimes referred to as a bottom valve or BOV (bottom operated valve), is generally provided for each for each fuel storage compartment of a multi-compartment, road-going fuel tanker.

Conventionally, such valves have an upper part which locates inside the compartment itself and a lower part, either in a tee or elbow configuration, which locates outside and below the compartment. Typically, the various valves serving the different compartments are arranged in series with one another in a manifold configuration. Alternatively, each compartment may have its own valve connected to an independent discharge coupler. When the relevant compartment is to be filled with fuel at a fuel depot, the valve is opened pneumatically to allow fuel to flow through the valve under pressure into the compartment. Similarly, when fuel is to be delivered from the compartment into a reservoir or tank at, say a fuel filling station, the valve is again opened pneumatically to allow fuel to discharge from the compartment.

At least in a known, tee-configured footvalve used for this purpose, the pneumatic actuating mechanism for the valve is situated largely within the flow passage of the tee-piece or elbow and so can interfere with that flow.

The known mechanisms are also rather complicated and expensive to manufacture and assemble.

SUMMARY OF THE INVENTION

According to the present invention there is provided a pneumatically operated, pressure-balanced fuel delivery footvalve for a fuel tanker, the footvalve comprising: - a valve body defining a flow passage having a valve seat therein; - a poppet which is slidable between a closed position in which it seats on the valve seat to close the flow passage and prevent fuel flow therethrough and an open position in which it is spaced from the valve seat to open the flow passage and allow fuel flow therethrough; - a piston relative to which the poppet can slide; - a shaft on which the poppet is slidable, the shaft carrying the piston, being fixed in position relative to the body and having an internal bore which is in use connected {o a source of pneumatic pressure, - a spring acting between the piston and the poppet to bias the poppet to the closed position; - a cap connected to the poppet and defining, with the piston, a pressure space which is in communication with the bore of the shaft; whereby when the valve is to be opened, air under pressure is caused to flow through the bore of the shaft into the pressure space where it acts on the cap to drive the cap away from the piston with the result that the poppet is moved against the bias of the spring from its closed to its open position.

Preferably, the poppet is hollow and is arranged to be exposed in use to internal pressure force biasing it to the closed position and external pressure force in the flow passage biasing it to the open position, the areas on which the pressure forces act being selected such that the internal pressure force is marginally greater than the external pressure force. There may be one or more ports providing communication between the interior of the poppet and the exterior of the poppet in the flow passage.

In one version of the invention, the flow passage is provided in an elbow configuration and the shaft extends centrally in one leg of the elbow. In one embodiment of this version the shaft is supported by at least one radial arm located in the said one leg of the elbow, and a compressed air port extends through the radial arm into communication with the bore of the shaft. In another embodiment, the elbow includes a bend with an outer wall and the shaft is supported by an inward extension of the outer wall, with a compressed air port extends through the inward extension into communication with the bore of the shaft. in another version of the invention the footvalve is provided in a tee configuration and the shaft extends centrally in the tee of the tee configuration. The shaft can be supported by at least one radial arm located in the tee of the tee configuration, again with a compressed air port extending through the radial arm into communication with the bore of the shaft.

In the preferred embodiments, the poppet has a cup shape with an outer, cylindrical skirt surrounding the piston, a base and a central, hollow boss which is slidable on the shaft. The abovementioned port(s) may extend through the base of the poppet to provide communication between the interior of the poppet and the underside of the poppet in the flow passage.

The cap may be fixed to the skirt of the poppet, and the skirt may be surrounded by a mesh screen. Conveniently, the piston includes a central boss and the spring locates over the central boss of the poppet and over the central boss of the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings.

In the drawings:

Figure 1 shows a perspective view of a footvalve according to the invention in an elbow configuration;

Figure 2 shows a plan view of the valve seen in Figure 1;

Figure 3 shows a cross-section at the line 3-3 in Figure 2;

Figure 4 shows a cross-section at the line 4-4 in Figure 2;

Figure 5 shows a perspective view of a footvalve according to the invention in a tee configuration;

Figure 6 shows a plan view of the valve seen in Figure 5;

Figure 7 shows a cross-section at the line 7-7 in Figure 6,

Figure 8 shows a cross-section at the line 8-8 in Figure 6;

Figure 9 shows a perspective view of a footvalve according to the invention in an low profile elbow configuration;

Figure 10 shows a plan view of the valve seen in Figure 9;

Figure 11 shows a cross-section at the line 11-11 in Figure 10;

Figure 12 shows a cross-section at the line 12-12 in Figure 10; and

Figure 13 diagrammatically illustrates a typical multi-compartment tanker and footvalve layout.

DESCRIPTICN OF PREFERRED EMBODIMENTS in Figure 13, the numeral 10 indicates the tanker body of a road-going fuel tanker. The tanker body 10 is subdivided internally by bulkheads 12 into a number of independent fuel compartments, 10.1, 10.2, 10.3, 10.4. Each compartment has a footvalve FV, according to the invention, at the bottom thereof. The footvalves are connected to one another in series by a line 16 which is in turn connected to a branch line 18. The footvalves at the ends of the line are arranged in elbow configurations while those in the middle are arranged in tee configurations.

In a tanker filling mode, i.e. when the compartments of the tanker body 10 are to be filled with fuel, the branch 18 extends to a source of fuel under pressure. In a fuel discharge mode, i.e. when the compartments of the tanker body are to be discharged into a reservoir or storage tank at, say a filing station, the branch 18 extends to the reservoir or tank.

Each of the footvalves FV is opened and closed pneumatically to allow or prevent fuel flow to or from the associated compartment 10.1 to 10.4.

Figures 1 to 4 illustrate an elbow configured footvalve according to the invention. The footvalve, designated by the numeral 20, has an aluminium body 22 of elbow shape and defining an internal flow passage 24. The body extends from an end 26 where there is a holed flange for connection to the line 16 to an upper end 28 formed with a flange 30 which is in use fixed to the underside of the tanker. A valve seat 32 is formed internally in the flow passage at the upper end 28.

In the closed valve position seen in Figures 3 and 4, a hollow aluminium poppet 34 seats on the valve seat 32. The poppet has a central, hollow boss 36 and an outer, cylindrical skirt 38 as illustrated. The boss 36 is arranged slidably on a central vertical, stainless steel shaft 40. The lower end of the shaft 40 is threaded and is fixed relative to a member 42 by a nut

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The member 42 is supported centrally in the flow passage 24 by radial arms 45 integral with the body 22. Only one such arm 45 is visible in Figure 4.

It will accordingly be understood that the shaft 40 is fixed relative to the body 22 of the footvalve.

A tapered upper end of the shaft 40 extends centrally through a piston 46 and is fixed relative to the piston by a nut 48 which engages a threaded upper extremity of the shaft above the piston. Seals 50 are located between the shaft and piston as illustrated.

The skirt 38 of the poppet is located slidably about the piston and is sealed with respect to the piston by sealing rings 52. A Teflon Glyde ring 54 prevents direct contact between the aluminium poppet and piston. A stainless steel cap 56 is fixed over the upper end of the skirt 38 by a locking ring 58. A sealing ring 60 forms a seal between the cap and skirt. The numeral 62 indicates a pressure space between the cap and the upper surface of the piston 46.

From the above description it will be understood that the piston 46 is fixed in position relative to the body 22 of the footvalve. A coil spring 64 is mounted about a central boss on the underside of the piston 46 and the boss 36 of the poppet 34, and acts in compression between the piston and the poppet in order to bias the poppet downwardly to seat on the valve seat 32.

The skirt 38 of the poppet is surrounded by a cylindrical mesh screen 66 held in position between spaced flanges 68 and 70 which are connected to one another by external tie rods 72.

The shaft 40 has an axial bore 74 extending from an inlet 76 to its upper end, above the piston 46. A compressed air port 78 extends, through the radial arm 46 from an external pneumatic supply line 80 to the inlet 76.

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It will be understood that components of the footvalve located above the flange 30 project upwardly into the tanker compartment which the footvalve serves.

The operation of the footvalve is now described in the context of a tanker filling operation, i.e. fuel is to be pumped through the lines 18 and 16 and through the footvalve into the associated tanker compartment.

The lines 16 and 18 are pressurised with fuel and the footvalve is opened pneumatically to allow tanker filing to take place. This is achieved by appropriate manipulation of upstream pneumatic controls which admit compressed air into the line 80, port 78, inlet 76 and bore 74. The compressed air vents into the pressure space 62 above the piston 46. The upward force on the cap attributable to air pressure in the space 62 drives the cap upwardly, away from the piston. As the cap moves upwardly, it takes the poppet 34 with it, thereby lifting the poppet off the valve seat 32 against the action of the spring 64.

Fuel in the line 16 is now able to flow beneath the poppet and laterally outwardly through the screen 66 into the tanker compartment served by the footvalve.

When the compartment filling operation has been completed, the supply of compressed air to the line 80 is terminated. The line is vented with the result that the spring 64 drives the poppet downwardly to the closed position in which it seats once more on the valve seat 32.

The foot valve 20 described above is pressure-balanced. Ports in the form of holes 92 (only one visible in Figure 3) extend vertically through the base 93 of the poppet and provide communication between the line 16 and the space 94 existing between the piston and the poppet.

The relevant areas are designed such that when the poppet is in the closed position, the fuel pressure force acting downwardly on the poppet in the space 94 is marginally greater than the fuel pressure force acting upwardly on the poppet in the passage 24.

Thus in order to open the valve, the pneumatic pressure force only has to overcome the marginal fuel pressure force differential plus the bias of the spring 64 and other minor gravitational and frictional forces. In the absence of substantial pressure balancing, as just described, the pneumatically generated unseating force would have to be substantially higher, requiring substantially higher pneumatic pressure.

As mentioned above, the footvalve 22 is also used to discharge the tanker compartment. In this case, with the valve in an initial, closed condition, pneumatically generated force is again used to lift the cap 56, thereby unseating the poppet and allowing the tanker compartment to discharge under gravity through the mesh 66, beneath the poppet and through the flow passage 24 into the line 16 and branch 18. After the required discharge has taken place, the supply of pneumatic pressure is terminated, allowing the spring 64 to reseat the poppet again and close the footvalve.

Figures 5 to 8 illustrate a footvalve according to the invention set up in a tee configuration. In this case, the poppet, piston, shaft and related components are located in the tee of the configuration instead of the vertical arm of the elbow configuration described above. Apart from this the operation of the footvalve is in all respects the same as is described above for the elbow configuration. Although present, the compressed air port 78 and pressure-balancing holes 92 are not visible in Figures 5 to 8.

Figures 9 to 12 illustrate another elbow configuration footvalve which is of lower profile than the footvalve of Figures 1 to 4. In this case, the lower end of the shaft 40 is fixed directly to an inward extension 100 of the body 22, once again by means of a nut 44 engaged with a threaded lower end of the shaft.

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In this case, the compressed air port 78 extends within the extension 100, and the pressure-balancing holes 92 are visible. In all other respects, the footvalve seen in Figures 9 to 12 operates in the same way as the footvalves illustrated in Figures 1 to 4 and Figures 5 to 8.

With particular reference to Figures 5 to 8 it will be noted that the operating mechanism of the footvalve is situated almost entirely out of the flow passage extending between the ends 102 and 104 of the valve body. As a result, the mechanism does not interfere in any meaningful way with fuel flow between the ends 102 and 104 during filling or discharge of upstream or downstream compartments.

Also, in each of the described configurations, the operating mechanism is relatively simple and compact with only a small number of moving parts.

Claims (1)

1. A pneumatically operated, pressure-balanced fuel delivery footvalve for a fuel tanker, the footvalve comprising:

   - a valve body defining a flow passage having a valve seat therein;

   - a poppet which is slidable between a closed position in which it seats on the valve seat to close the flow passage and prevent fuel flow therethrough and an open position in which it is spaced from the valve seat to open the flow passage and allow fuel flow therethrough;

   - a piston relative to which the poppet can slide;

   - a shaft on which the poppet is slidable, the shaft carrying the piston, being fixed in position relative to the body and having an internal bore which is in use connected to a source of pneumatic pressure;

   - a spring acting between the piston and the poppet to bias the poppet to the closed position;

   - a cap connected to the poppet and defining, with the piston, a pressure space which is in communication with the bore of the shaft;

   whereby when the valve is to be opened, air under pressure is caused to flow through the bore of the shaft into the pressure space where it acts on the cap to drive the cap away from the piston with the result that the poppet is moved against the bias of the spring from its closed to its open position.

   A footvalve according to claim 1 wherein the poppet is hollow and is arranged to be exposed in use to internal pressure force biasing it to the closed position and external pressure force in the flow passage biasing it to the open position, the areas on which the pressure forces act heing selected such that the internal pressure force is marginally greater than the external pressure force.

   3. A footvalve according to claim 2 comprising one or more ports providing communication between the interior of the poppet and the exterior of the poppet in the flow passage.

   4. A footvalve according to claim 3 wherein the flow passage is provided in an elbow configuration and the shaft extends centrally in one leg of the elbow.

   5. A footvalve according to claim 4 wherein the shaft is supported by at least one radial arm located in the said one leg of the elbow.

   6. A footvalve according to claim 5 wherein a compressed air port extends through the radial arm into communication with the bore of the shaft.

   7. A footvalve according to claim 4 wherein the elbow inciudes a bend with an outer wall and the shaft is supported by an inward extension of the outer wall.

   A footvalve according to claim 7 wherein a compressed air port extends through the inward extension into communication with the bore of the shaft.

   9. A footvalve according to claim 3 wherein the footvalve is provided in a tee configuration and the shaft extends centrally in the tee of the tee configuration.

   10. A footvalve according to claim 9 wherein the shaft is supported by at least one radial arm located in the tee of the tee configuration.

   11. A footvalve according to claim 10 wherein a compressed air port extends through the radial arm into communication with the bore of the shaft.

   12. A footvalve according to any one of claims 3 to 11 wherein the poppet has a hollow cup shape with an outer, cylindrical skirt surrounding the piston, a base and a central, hollow boss which is slidable on the shaft.

   13. A footvalve according to claim 12 wherein one or more ports extend through the base of the poppet to provide communication between the interior of the poppet and the underside of the poppet in the flow passage.

   A footvalve according to claim 12 or claim 13 wherein the cap is fixed to the skirt of the poppet.

   14. A footvalve according to any one of claims 12 to 14 wherein the skirt of the poppet is surrounded by a mesh screen.

   15. A footvalve according to claim 14 wherein the mesh screen is located between spaced flanges connected to one another by tie rods.

   16. A footvalve according to any one of claims 12 to 15 wherein the piston includes a central boss and the spring locates over the central boss of the poppet and over the central boss of the piston.

   17. A pneumatically operated, pressure-balanced fuel delivery footvalve substantially as herein described with reference to Figures 1 to 4, Figures 5 to 8 or Figures 9 to 12 of the accompanying drawings. Dated thik 31% day of March 2006 Ld Spat i’ Fisher ppficant’'s Patent Attorneys