WO1997048926A2

WO1997048926A2 - Two-way pressure relief valve

Info

Publication number: WO1997048926A2
Application number: PCT/IB1997/000729
Authority: WO
Inventors: Guilherme Dos Santos
Original assignee: Guilherme Dos Santos
Priority date: 1996-06-17
Filing date: 1997-06-17
Publication date: 1997-12-24
Also published as: AR007325A1; WO1997048926A3; BR9602811A; UY24559A1

Abstract

The invention described in the specification relates to a two-way relief valve which may be attached to fuel vessels and conduits to relieve pressure or vacuum in the vessels or conduits. The valve (10) contains a valve body (12) defining a cavity (20), means (22) for attaching the valve to a vessel or conduit and inlet (66, 66', 54) and exit (26, 26', 30) ports on the valve body (12) open to the cavity (20). The inlet (66, 66', 54) and exit (26, 26', 30) ports contain closure elements (32, 32', 34, 68, 68', 56) or valve members and bias means (40, 58, 70, 70', 38, 38') therefor which are resiliently biased to resist opening of the closure elements (32, 32', 34, 68, 68', 56). In use, the valve (10) promotes the reduction in vaporization of volatile fluids from a storage vessel or conduit thereby reducing pollution caused by the escape of vapors from the vessel or conduit and allows the flow of fluids into the vessel or conduits to reduce damage to the vessel or conduit caused by excessive vacuum.

Description

TWO-WAY PRESSURE RELIEF VALVE

Field of the Invention

The invention relates to a valve, particularly a valve for controlling the loss of volatile compounds from a vessel or conduit. Background During the filling of fuel storage or transportation vessels, the air or gas inside the vessel generally must be vented in order prevent damage to the vessel from over pressurization. When fuel is removed from such vessels, air or gas often must be permitted to enter the vessel to prevent damage to the vessel and associated conduits from increased vacuum since many fuel tanks, vessels and associated conduits are not rated for high vacuum conditions.

One means for controlling the pressure or vacuum in a vessel or conduit is to provide an atmospheric vent, rupture disc or check valve on the vessel or conduit.

However, such measures tend to allow volatiles to escape to the atmosphere which contributes to environmental problems and represents a loss of valuable material since such devices operate either for relieving pressure or vacuum, but not both.

It is therefore an object of the invention to provide a vent valve for fuel storage vessels and conduits to control or limit the release of volatile compounds to the atmosphere.

Another object of the invention is to provide a vent valve for storage vessels and conduits which enables entry of air to the vessel or conduit while limiting the release of volatile compounds from the vessel or conduit.

A further object of the invention is to provide a vent valve for fuel storage vessels and conduits which promotes condensation of vapors in the vessel or conduit in order to conserve valuable materials. Summary of the Invention

With regard to the above and other objects and advantages, the invention provides a two-way pressure relief valve which comprises a valve body, a cavity

- 1 -

C0NFIRMATI0N COPY located within the valve body, a vessel or conduit connector port on the valve body for connecting the cavity in flow communication with the interior of a vessel or conduit, an exit port on the valve body for providing fluid flow from the cavity to outside the valve body and an inlet port on the valve body for providing fluid flow into the cavity from outside the valve body. An exit valve member is supported on the valve body adjacent the exit port for movement between a closed position closing the exit port against fluid flow out of the cavity and an open position opening the port to enable fluid flow out of the cavity through the exit port. Exit bias means are provided for biasing the exit valve member against movement from the closed position to the open position, to yieldably permit movement of the valve member from the closed position to the open position when the force of pressure in the cavity on the exit valve member exceeds a high pressure value and to urge the exit valve member back to the closed position when the force of pressure in the cavity on the exit valve member drops to below the high pressure value. An inlet valve member is supported on the valve body adjacent the inlet port for movement between a closed position closing the inlet port against fluid flow into the cavity from outside the valve body and an open position opening the inlet port to enable fluid flow into the cavity through the inlet port. Inlet bias means are provided for biasing the inlet valve member against movement from the closed position to the open position, to yieldably permit movement of the inlet valve member from the closed position to the open position when the force of pressure in the cavity on the inlet valve element drops below a low pressure value and to urge the inlet valve member back to the closed position when the force of pressure in the cavity on the inlet valve element exceeds the low pressure value.

In another aspect the invention provides a method for reducing loss of a volatile compound from a vessel or conduit to the atmosphere which comprises providing a two-way pressure relief valve which comprises a valve body, a cavity located within the valve body, a vessel or conduit connector port on the valve body for connecting the cavity in flow communication with the interior of a vessel or conduit, an exit port on the valve body for providing fluid flow from the cavity to outside the valve body and an inlet port on the valve body for providing fluid flow into the cavity from outside the valve body. An exit valve member is supported on the valve body adjacent the exit port for movement between a closed position closing the exit port against fluid flow out of the cavity and an open position opening the port to enable fluid flow out of the cavity through the exit port. Exit bias means are provided for biasing the exit valve member against movement from the closed position to the open position, to yieldably permit movement of the valve member from the closed position to the open position when the force of pressure in the cavity on the exit valve member exceeds a high pressure value and to urge the exit valve member back to the closed position when the force of pressure in the cavity on the exit valve member drops to below the high pressure value. An inlet valve member is supported on the valve body adjacent the inlet port for movement between a closed position closing the inlet port against fluid flow into the cavity from outside the valve body and an open position opening the inlet port to enable fluid flow into the cavity through the inlet port. Inlet bias means are provided for biasing the inlet valve member against movement from the closed position to the open position, to yieldably permit movement of the inlet valve member from the closed position to the open position when the force of pressure in the cavity on the inlet valve element drops below a low pressure value and to urge the inlet valve member back to the closed position when the force of pressure in the cavity on the inlet valve element exceeds the low pressure value. The connector port of the valve is attached to an exhaust port of a vessel or conduit containing the volatile compound.

An advantage of the two-way relief valve of the invention is that it may be economically produced and provides reliable relieve of both pressure and vacuum in a vessel or conduit without the need to use separate vacuum and pressure relief devices. The bias means may be adjustable so that the closure members of the valve may be set to open on a high pressure value above the vapor pressure of the material in the vessel or conduit to promote condensation of fuel in the vessel or conduit while permitting non-condensible gases to escape thereby reducing the pressure in the vessel or conduit to a safe operating level. For the purposes of the invention, "vessel" means any storage, holding or transportation tank which may be used to contain fluids including tank trucks, storage tanks, pressure vessels, transportation tanks and the like. Brief Description of the Drawings

Other features and advantages of the invention will now be further described in the following detailed description of a preferred embodiment of the invention considered in conjunction with the drawings in which:

Figure 1 is a cross-sectional view of a two-way relief valve according to the invention;

Figure 2 is a top plan view of a two-way relief valve according to the invention with a protective cover removed from the valve;

Figure 3 is a bottom plan view of a two-way valve according to the invention; and

Figure 4 is a side view of a two-way relief valve according to the invention showing the valve and a protective cover therefor. Detailed Description of the Invention

With reference to Figs. 1 and 2 there is shown a valve 10 having a valve body 12 comprising an upper concave portion 14 and an lower concave portion 16 which are attached to one another by means of attachment devices 18 so that a cavity 20 is provided between the upper portion 14 and the lower portion 16. The upper and lower portions 14 and 16 may be made from a variety of materials provided the materials are resistant to weather conditions and corrosion and are compatible with the fluids for which the valves are used. Suitable materials include, but are not limited to cast iron, aluminum, mild steel, galvanized iron, stainless steel, nickel, brass and various commercially available metals and alloys known by those of ordinary skill for use in such applications. The preferred overall shape of the valve 10 is oval or egg- shaped as illustrated by the plan views of Figs. 2 and 3, however the valve may have any suitable size and shape provided the shape accommodates the pertinent features thereof and the valve is of a size suitable for the particular application. A vessel or conduit connector port 22 is provided on the lower portion 16 of the valve body 12 for connecting the valve 10 to an exhaust or pressure relief port on a vessel or conduit. The connector port 22 contains an engagement device 24 for fixedly attaching the valve 10 to the vessel or conduit. The engagement device may be a flange, a male or a female threaded projection 24 pending from the lower portion 16 of the valve 10 as illustrated in Fig. 1. Any suitable connection means may be used to attach the valve 10 to a vessel or conduit.

The upper portion 14 of the valve 10 contains at least one exit port and preferably two exit ports 26 and 26' and exit valve members or closure elements 32 and 32' supported on the valve body 12 adjacent the exit ports which open above a high pressure value to permit flow of gases from the cavity 20 which are displaced from the vessel as the vessel is being filled with a fluid.

The exit valve members 32 and 32' are resiliently biased by exit bias means 38 and 38' which are attached between the valve members 32 and 32' and the upper portion 14 of the valve body 12. The bias means 38 and 38' yieldably permit movement of the valve members 32 and 32' from a closed position to an open position with respect to exit ports 26 and 26' when the force of pressure in the cavity exceeds a high pressure value and urge the valve members 32 and 32' toward the upper portion 14 of the valve body 12 to close the exit ports 26 and 26' when the pressure in the cavity 20 is below the high pressure value.

A third exit port 30 is most preferably provided in the upper portion 14 of the valve body 12. Exit port 30 contains a exit valve member 34 supported on the valve body adjacent exit port 30 and an exit bias means 40 which is attached between the valve member 34 and the upper portion 14 of the valve body 12. Exit bias means 40 yieldably permits movement of the valve member 34 from a closed to an open position when the force of pressure in the cavity is above a high pressure value and urges the exit valve member 34 toward the upper portion 14 of the valve body 12 to close the exit port 30 when the pressure in the cavity is below the high pressure value. The preferred bias means 38, 38' and 40 comprise elongate threaded rods 42, 42' and 44, springs 46, 46' and 48 attached the rods 42, 42' and 44 between the valve members 32, 32' and 34 and spring retainer nuts 50, 50' and 52 used for retaining the springs 46, 46' and 48 on the rods 42, 42' and 44. The exit bias of the bias means 38, 38' and 40 may be controlled by adjusting the retainer nuts 50, 50' and 52 along the axis of the respective rods 42, 42' and 44. In this way, the valve may be adapted for use with a variety of volatile liquids in the vessel or conduit to which the valve is attached.

Each of the exit bias means 38, 38' and 40 may be adjusted to different bias settings to provide stageable opening of the exit valve members 32, 32' and 34. For example, exit valve member 32 may be set to open when the pressure in the cavity is above a first pressure, exit valve member 32' may be set to open when the pressure rises from the first pressure to a second pressure and exit valve member 34 may be set to open when the pressure rises from the second pressure to a third pressure. It is particularly preferred that exit valve member 34 further comprise an inlet port 54 having a inlet valve member 56 supported on the exit valve member 34. An inlet bias means 58 is attached between the inlet valve member 56 and the exit valve member 34 and comprises an elongate threaded rod 60, spring 62 and spring retainer nut 64. The amount of bias of inlet bias means 58 may be changed by adjusting the retainer nut 64 along the axis of the rod 60 to control the bias on inlet valve member 56 to yieldably permit movement of the inlet valve member 56 from a closed position to an open position when the pressure in the cavity is below a low pressure value and to urge the inlet valve member 56 closed when the pressure in the cavity exceeds the low pressure value. The lower portion 16 of the valve body 12 may also contain one or more inlet ports 66 and 66', inlet valve members 68 and 68' supported on the lower portion 16 of the valve body 12 adjacent the inlet ports and inlet bias means 70 and 70' for biasing the inlet valve member 68 and 68' against movement from a closed position adjacent the inlet ports 66 and 66' to an open position when the pressure in the cavity 20 falls below a low pressure value. The inlet bias means 70 and 70' comprise elongate threaded rods 72 and 72' attached between the valve members 68 and 68' and the lower portion 16 of the valve body 12. Springs 74 and 74' are attached to the rods 72 and 72' and are retained on the rods by retainer nuts 76 and 76'. Like the other bias means described above, the amount of bias of bias means 70 and 70' may also be changed by adjusting the nuts 76 and 76' along the axis of the rods 72 and 72' to provide opening of inlet valve members 68 and 68' at the same or different low pressure settings.

While the inlet and exit bias means have been shown and described as threaded rods with springs and retainer nuts, it will be recognized those or ordinary skill in the art that other bias means may be used to effectively urge the inlet and exit valve members closed. For example, leaf spring elements may be used or weights attached to the exit valve members or a combination of other resilient bias means and weights may be used.

Exit of the inlet and exit valve members may be made from a variety of materials similar to the materials which may be used for the valve body 12. Accordingly any suitable materials may be used which are compatible with the valve body materials and the fluids in the vessels and conduits.

Fig. 2 is a top plan view A-A of the valve 10 of Fig. 1 having an oval shape showing the relative positions of the valve members 32, 32', 34 and 56 with respect to the upper portion 14 of the valve body 12. In the illustrated embodiment, exit ports 26 and 26' are diametrically opposed to one another and exit port 30 containing inlet port 56 is centrally located relative to exit ports 26 and 26'.

Fig. 3 is a bottom plan view B-B of the valve 10 of Fig. 1 showing the relative positions of inlet ports 68 and 68' and connector port 22 with respect to the lower portion 16 of the valve body 12. Also illustrated in Fig. 3 is a flame arrester device 74 which comprises an open mesh screen for blocking flames from entering the vessel or conduit. The arrester device 74 is fixedly attached in the connector port 22 by welding or bolting the screen to the cavity side of the lower portion 16 of the valve body 12. In a particularly preferred embodiment as shown in Fig. 4, the two-way pressure valve 10 according to the invention further comprises a valve cover 76 which may be attached to the upper portion of rods 44 by means of cover nuts 78. The valve cover 76 has a dimension and is attached to the valve 10 in such a manner as to provide a gap or space 80 between the cover 76 and the upper portion 14 of the valve body 12. The gap or space 80 permits the flow of gases through exit ports 26, 26' and 30 to outside the cavity 20 under a pressure condition which is above the high pressure value or into the cavity 20 from outside the cavity through inlet port 56 at a pressure which is below the low pressure value. The cover 76 is also suitably sized to protect the movable portions of the valve 10 from adverse weather conditions such as ice and snow so that operation of the valve is not impeded.

Each of the inlet ports and exit ports may contain sealing materials or gaskets (not shown) to provide a positive seal between the valve member and respective valve body portion. Suitable materials for sealing between the valve members and the ports include o-rings or other materials which are conventionally used to provide a positive seal between rigid elements.

In operation, for example when filling a fuel vessel with fuel, the valve 10 promotes condensation of fuel vapors and return of the condensed vapors to the vessel by maintaining a pressure in the vessel or conduit above the vapor pressure of the fuel. Exit valve members 32, 32' and 34 are resiliently biased by exit bias means 38, 38' and 40 so that valve members 32, 32' and 34 open at a pressure value above the vapor pressure of fuel in the vessel or conduit. Because the valve members 32, 32' and 34 are set using bias means 38, 38' and 40 to allow movement of valve members 32, 32' and 34 to open the exit ports 26, 26' and 30 above the vapor pressure of the fuel, any fuel in the vapor space above the liquid level in the vessel is caused to condense and return to the liquid phase. Non-condensible gases are permitted to escape through exit ports 26, 26' and 30 when the pressure in the vessel or conduit exceeds the force exerted by bias means 38, 38' and 40 on exit valve members 32, 32' and 34. During removal of fuel from a storage vessel, inlet valve members 56, 68 and 68' are resiliently biased by inlet bias means 58, 70 and 70' to permit the valve members 56, 68 and 68' to open so that sufficient air will enter the vessel or conduit through inlet ports 54, 66 and 66' in order to maintain the pressure in the vessel or conduit above a low pressure value. Inlet bias means 70 and 70' resiliently urge valve members 68 and 68' toward the lower portion 16 of the valve body 12 to close inlet ports 66 and 66' when the pressure in the cavity 20 is above a low pressure value to substantially prevent vapors from escaping of vapors from the vessel. Likewise inlet bias means 58 resiliently urges valve member 56 toward exit valve member 34 to close inlet port 54 when the pressure in the cavity 20 is above the low pressure value. Because air is allowed to enter the vessel during transfer of fuel from the vessel, the vessel is protected from damage caused by a low pressure which exceeds the ability of the vessel to withstand low or subatmospheric pressures.

Having described and illustrated preferred embodiments of the invention, it will be appreciated that various modifications, rearrangements and substitutions made to the invention by those of ordinary skill are within the spirit and scope of the appended claims.

Claims

What is claimed is:

1. A two-way pressure relief valve which comprises a valve body, a cavity located within the valve body, a vessel or conduit connector port on the valve body for connecting said cavity in flow communication with the interior of a vessel or conduit, an exit port on said valve body for providing fluid flow from said cavity to outside the valve body, an inlet port on said valve body for providing fluid flow into said cavity from outside the valve body, an exit valve member supported on said valve body adjacent said exit port for movement between a closed position closing said exit port against fluid flow out of said cavity and an open position opening said port to enable fluid flow out of said cavity through said exit port, exit bias means biasing said exit valve member against movement from said closed position to said open position, to yieldably permit movement of said valve member from said closed position to said open position when the force of pressure in the cavity on the exit valve member exceeds a high pressure value and to urge said exit valve member back to said closed position when the force of pressure in said cavity on said exit valve member drops to below said high pressure value, an inlet valve member supported on said valve body adjacent said inlet port for movement between a closed position closing said inlet port against fluid flow into said cavity from outside said valve body and an open position opening said inlet port to enable fluid flow into said cavity through said inlet port and inlet bias means biasing said inlet valve member against movement from said closed position to said open position, to yieldably permit movement of said inlet valve member from said closed position to said open position when the force of pressure in said cavity on said inlet valve element drops below a low pressure value and to urge said inlet valve member back to said closed position when the force of pressure in said cavity on said inlet valve element exceeds said low pressure value.

2. The valve of Claim 1 further comprising at least two exit ports having exit valve members and exit bias means associated therewith.

3. The valve of Claim 2 further comprising at least two inlet ports having inlet valve members and inlet bias means associated therewith.

4. The valve of Claim 3 further comprising an exit valve member containing an inlet port, inlet valve member and inlet bias means thereon.

5. The valve of Claim 1 further comprising at least two inlet ports having inlet valve members and inlet bias means associated therewith.

6. The valve of Claim 1 wherein the exit valve member further comprises an inlet port, inlet valve member and inlet bias means thereon.

7. The valve of Claim 1 wherein the inlet and exit bias means are adjustable to control the bias of the inlet and outlet valve members.

8. The valve of Claim 1 further comprising a flame arrester adjacent the vessel or conduit connector port.

9. A vacuum and pressure relief valve which comprises a valve body having an upper portion and a lower portion defining a cavity therebetween, a connector port on the lower portion of the valve body for connecting said cavity in fluid flow communication with a vessel or conduit, at least two vacuum relief ports on said valve body having inlet valve members and at least two pressure relief ports on said valve body having exit valve members for connecting said cavity in fluid flow communication with the outside of said valve body when said ports are open, said vacuum and pressure relief ports each containing resiliently biased closure elements.

10. The relief valve of Claim 9 wherein the valve body is comprised of an oval shaped valve body.

1 1. The relief valve of Claim 10 wherein the vacuum relief ports are located in the lower portion of the valve body on diametrically opposing sides of said inlet port.

12. The relief valve of Claim 9 further comprising exit bias elements for urging said exit valve members closed below a high pressure value in said cavity and inlet bias elements for urging said inlet valve members closed above a low pressure value in said cavity.

13. The relief valve of Claim 12 wherein the inlet and exit bias elements are adjustable to control the opening pressure exerted on the valve members from the cavity or outside the cavity.

14. The relief valve of Claim 9 wherein the pressure relief ports are located on the upper portion of the valve body wherein the valve further comprises a protective cover attached to the upper portion of the valve body over the pressure relief ports.

15. The relief valve of Claim 9 further comprising a flame arrester adjacent the connector port.

16. The relief valve of Claim 15 wherein the flame arrester comprises an open mesh web in said connector port.

17. A method for reducing loss of a volatile compound from a vessel or conduit to the atmosphere which comprises providing a two-way pressure relief valve which comprises a valve body, a cavity located within the valve body, a vessel or conduit connector port on the valve body for connecting said cavity in flow communication with the interior of a vessel or conduit, an exit port on said valve body for providing fluid flow from said cavity to outside the valve body, an inlet port on said valve body for providing fluid flow into said cavity from outside the valve body, an exit valve member supported on said valve body adjacent said exit port for movement between a closed position closing said exit port against fluid flow out of said cavity and an open position opening said port to enable fluid flow out of said cavity through said exit port, exit bias means biasing said exit valve member against movement from said closed position to said open position, to yieldably permit movement of said valve member from said closed position to said open position when the force of pressure in the cavity on the exit valve member exceeds a high pressure value and to urge said exit valve member back to said closed position when the force of pressure in said cavity on said exit valve member drops to below said high pressure value, an inlet valve member supported on said valve body adjacent said inlet port for movement between a closed position closing said inlet port against fluid flow into said cavity from outside said valve body and an open position opening said inlet port to enable fluid flow into said cavity through said inlet port and inlet bias means biasing said inlet valve member against movement from said closed position to said open position, to yieldably permit movement of said inlet valve member from said closed position to said open position when the force of pressure in said cavity on said inlet valve element drops below a low pressure value and to urge said inlet valve member back to said closed position when the force of pressure in said cavity on said inlet valve element exceeds said low pressure value and attaching the connector port of the valve to an exhaust port of a vessel or conduit containing the volatile compound.

18. The method of Claim 17 wherein the exit bias means are adjustable, further comprising adjusting the exit bias means to a high pressure value which is above the vapor pressure of the volatile compound in the vessel or conduit.

19. The method of Claim 18 wherein the inlet bias means are adjustable, further comprising adjusting the inlet bias means to a low pressure value to open said inlet valve members when a volatile fluid is flowing out of said vessel or conduit through an exit port therefor to promote a pressure in the vessel or conduit sufficient to prevent damage to the vessel or conduit from excessive vacuum as the fluids are flowed from the vessel or conduit.

20. The method of Claim 17 wherein the inlet bias means are adjustable, further comprising adjusting the inlet bias means to a low pressure value to open said inlet valve members when a volatile fluid is flowing out of said vessel or conduit through an exit port therefor to promote a pressure in the vessel or conduit sufficient to prevent damage to the vessel or conduit from excessive vacuum as the fluids are flowed from the vessel or conduit.