Poppet shear protection apparatus and system

A springless shear protection device for use with a valve, the device comprising a poppet, the poppet including a bore. The poppet including first and second openings at distal ends of the poppet. A seat plug is disposed in the poppet bore, the seat plug is moveable within the poppet bore. A shear tube with first and second ends extending through the first opening of the poppet, the first end abutting the seat plug through the first opening of the poppet and the shear tube displacing the seat plug from the top of the poppet bore. The poppet is attachable to the valve and when attached a compressed gas or liquid passes through the poppet into the valve. When the shear tube is removed, the seat plug forcibly engages the top of the poppet bore and the seat plug blocks the flow of the compressed gas or liquid.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

FIELD OF THE INVENTION

The present invention relates generally to shear protection devices for tanks containing high-pressure gases. More specifically, the present invention relates to shear protection devices for truck-borne and stand-alone compressed gas cylinders.

BACKGROUND

Various types of compressed gases are commonly transported in long, narrow cylinders, or “tubes,” mounted directly on a tractor trailer chassis or in a “module,” or a box frame containing the cylinders that is loaded onto a flat bed trailer. These truck-borne compressed gas cylinders are often required by law to be fitted with relief devices designed to relieve pressure from the compressed gas cylinders in the event of cylinder over-pressurization or fire. These relief devices are typically attached to each end of a cylinder and take two major forms: cluster-type relief devices (typically for hazardous gases) and angle-type relief devices (typically for non-hazardous gases). The relief devices typically protrude from the compressed gas cylinders and are subject to shearing forces. These relief devices provide protection for over pressurization, however, due to their physical structure, are prone to inadvertent damage such as having the relief device sheared off of the compressed gas cylinder. When such a shearing of a valve or relief device occurs, the compressed gas escapes through an uncontrolled opening in the compressed gas cylinder to the atmosphere.

In U.S. Pat. No. 5,832,947, entitled “Gas Shut-Off and Pressure Relief Valve for a High Pressure Gas Vessel,” issued to Andrew Niemczyk, a pressure relief valve is disclosed. The disclosed pressure relief valve has a threaded body that engages the side port in fluid communication with the gas passage. The side port has a radially extending shoulder that seats an annular sealing ring. A rupture disc, made from brass, is pressed by the threaded body against the sealing ring. During operation, the gas shut-off and pressure relief valve extends away from the compressed gas cylinder. The relief valve provides protection from an unintentional over pressurization; however, the protrusion of the relief valve increases the probability of an inadvertent shear of the relief valve.

In U.S. Pat. No. 4,269,214, entitled “Safety Pressure Relief Device,” issued to Calvin. C. Forsythe, et al., a safety pressure relief device is disclosed. The disclosed safety pressure relief device has a casing with a threaded connection and a concentric axial bore there through. The open end of the casing engages a concave-convex rupture disc which is ruptured with a knife means including a plurality of spaced cutting teeth. An annular outlet ring is connected to the casing by a continuous heli-arc weld. The weld also connects the rupture disc and the knife means to the casing. Again, protection is provided for an over pressurization. However, the probability of an inadvertent shear of the relief device is increased.

FIG. 1illustrates another prior art relief device and its attachment to a compressed gas cylinder. The relief device20does not attach directly to the cylinder10. Rather, the relief device20screws into a “bullplug”30, which itself screws into the cylinder10. Thus, the bullplug30has two sets of threads: a set of male straight threads32that engage a reciprocal female set12in the cylinder; and a set of female pipe threads34that engage a reciprocal set of male pipe threads24on the relief device20. Moreover, having the relief device20screw into the bullplug30, which in turn screws into the cylinder10, means that the relief device20protrudes farther from the cylinder10than it would if the relief device20screwed directly into the cylinder10. This greater protrusion presents a greater opportunity for a shear of the relief device20from the cylinder10in the event of an accident, resulting in uncontrolled compressed gas leakage.

Therefore, a need exists for a shear protection device that couples directly to its associated compressed gas tank utilizing a valve or relief device, thereby lessening the likelihood of a valve or relief device shear—and the associated uncontrolled leakage—in the event of an accident.

Accordingly, it is an object of the present invention to provide a shear protection device for compressed gas cylinders that attaches directly to its cylinder. It is a further object of this invention to provide a shear protection device that attaches directly to relief devices for compressed gas cylinders that reduces or eliminates the likelihood of the uncontrolled compressed gas leakage due to the valve or relief device shearing away from the main body in the event of an accident.

SUMMARY

The present invention is a springless shear protection device including a poppet, a seat plug and a retainer plug. The poppet is substantially a tube with a bore and with downstream and upstream openings where the diameter of the upstream opening in larger than the diameter of the seat plug and the diameter of the downstream opening is smaller than the diameter of the seat plug. The poppet further includes ventilation openings around the circumference of the poppet. The ventilation openings allowing a compressed gas or liquid to pass through the poppet into the bore for passage to a valve.

A seat plug is inserted through the upstream end of the poppet and moves within the poppet bore. A retainer plug is attached at the upstream end of the poppet, substantially closing off the upstream opening and blocking the exit of the seat plug through the upstream opening. The retainer plug includes an opening to allow for the compressed gas or liquid to forcibly abut the seat plug.

A valve with a threaded attachment is also shown. The valve includes an inlet. A shear tube is attached within the inlet of the valve. The poppet is attached to the valve inlet so that the upstream opening is inserted into the inlet of the valve. When the poppet is attached, the shear tube forcibly engages the seat plug causing the seat plug to engage the retaining plug. When the seat plug is engaging the retaining plug, the compressed liquid or gas can pass through the ventilation openings of the poppet and pass through the valve inlet.

If the valve is sheared away, the internal force of the compressed gas or liquid forces the seat plug away from the retainer plug towards the downstream opening. The seat plug then engages the top of the bore of the poppet, blocking the passage of the compressed gas or liquid through the ventilation openings through the valve inlet.

DETAILED DESCRIPTION OF THE INVENTION

In the descriptions which follow, like parts are marked throughout the specification and drawings with the same numerals, respectively. The drawing figures are not necessarily drawn to scale and certain figures may be shown in exaggerated or generalized form in the interest of clarity and conciseness.

The present invention comprises generally a springless shear protection device, a valve, a threaded connection for coupling the springless shear protection device and valve to a compressed gas cylinder, and a seat plug that seals the cylinder outlet in the event of shearing of the valve. This disclosure describes numerous specific details that include specific structures, their arrangement, and functions in order to provide a thorough understanding of the present invention. One skilled in the art will appreciate that one may practice the present invention without these specific details.

An improved valve and springless shear protection device for high pressure gas cylinders directly engages the cylinder. A bore within the poppet of the springless shear protection device is in fluid communication with the pressurized cylinder contents. When shearing of the valve occurs, a seat plug disposed in the poppet seals the bore preventing the uncontrolled escape and possible ignition of the pressurized cylinder contents.

Referring now to the figures,FIGS. 2a,2b,2c,2d,2e,2f,2g,2hand3are exploded, side, top and bottom views of a valve and springless shear protection device and the interaction of same with a compressed gas cylinder according to one embodiment of the present invention. As shown inFIGS. 2a,2band3, a bullplug300attaches to a cylinder10. In one disclosed embodiment, the bullplug300includes male straight threads301that screw directly into the reciprocal female straight threads11of a compressed gas cylinder10. An “O” ring (typically made of rubber) and a backup ring (typically made of a synthetic, fluorine-containing resin such as TEFLON) (neither shown) create a seal between the bullplug300and the cylinder10. The bullplug300includes a bore302which is in fluid communication with the pressurized contents of the cylinder10. A valve103and a shear protection device101attach to form a valve and springless shear protection device100which attaches onto the downstream side of bullplug300, allowing the operator to manually control gas or liquid flow from the cylinder10. In one disclosed embodiment, the bullplug300includes female straight threads304on the downstream side that screw directly onto reciprocal male straight threads130of the valve and springless shear protection device100. However, a variety of various attachment techniques are available without detracting from the spirit of the invention.

As is shown inFIGS. 2a,2b,2c,2d,2e,2f,2gand2h, the valve and springless shear protection device100is formed from a valve103and a springless shear protection device101. The springless shear protection device101includes a shear tube109, a poppet112, a seat plug118and a retainer plug124. The valve103allows for the controlled escape of the pressurized contents of the cylinder10. The valve103includes a handle102for opening and closing of the valve103. When the valve103is in the open position, exit bore104, which is substantially perpendicular to the main axis of the valve103, is in fluid communication with inlet bore106, which is concentric with the main axis, allowing a gas or liquid to pass through the valve103. When the valve103is in the closed position, the fluid communication between the exit bore104and the inlet bore106is interrupted, preventing the compressed gas or fluid from passing from the inlet bore104to the exit bore106. The valve103includes male straight threads130which mate the valve103to the bullplug300. In another disclosed embodiment, the valve103includes male tapered threads130. The valve103further includes female straight threads160tapped to the inlet bore106. The female straight threads160accept male straight threads132of the springless shear protection device101.

The inlet bore106is bored to multiple different diameters. The first inner, smaller diameter portion of the inlet bore106is in fluid communication the second inner, larger diameter portion of the inlet bore106. The first inner diameter portion and the second inner diameter portion of the inlet bore106form a flat annular surface111at the transition between the first and second diameter bores. The second inner, larger diameter portion of the inlet bore106accepts the shear tube109and the shear tube109attaches to the flat annular surface111.

The shear tube109includes a shear tube bore108which is in fluid communication with the inlet bore106. The shear tube109has a first outer diameter and a second outer diameter. The first outer diameter is substantial equal to the second inner, larger diameter of the inlet bore106. The second diameter of the shear tube109is smaller than the first diameter. The first diameter of the shear tube109forms a continuous flange133around the periphery of the shear tube109. When the shear tube109is installed in the inlet bore106, the continuous flange133abuts the flat annular surface111of the valve103. In one disclosed embodiment, the shear tube continuous flange133is press fit to the inlet bore106, abutting the flat annular surface111. When installed, the shear tube109extends beyond the body of the valve103into the poppet bore114providing fluid communication for poppet bore114with shear tube bore108which remains in fluid communication with inlet bore106. The shear tube bore108and the inlet bore106have substantially equal inner diameters. In one disclosed embodiment, the shear tube109is formed from brass, however, a wide variety of materials may be used to form the shear tube109without detracting from the spirit of the invention, including but not limited to stainless steel.

The poppet112is substantially tubular and includes male straight threads132extended from the downstream end of the poppet112. The poppet112includes a poppet bore114through the main axis of the poppet112. The male straight threads132mate the poppet112to the female straight threads160of the valve103. When the poppet112and the valve103are mated, the shear tube109extends from the inlet bore106to within the downstream end of the poppet bore114. A seal gasket110is positioned between the valve103and the poppet112and seals the threaded connection to prevent leakage of the compressed gas or liquid.

The poppet bore114is bored to three different diameters. The first inner poppet diameter portion is bored to a diameter larger than the diameter of the shear tube109and forms a first inner poppet wall154. An intermediate inner poppet diameter portion is bored to a diameter larger than the first inner poppet diameter, but smaller than a third inner poppet diameter and forms an intermediate inner poppet wall152. The third inner poppet diameter portion is bored to a diameter substantially equal to the diameter of the retainer plug124and forms a third inner poppet wall150. The width of the shell of the first inner poppet diameter portion, including the male straight threads132, corresponds to the width of the female straight threads160of the valve103. The remaining outer poppet diameter portion is substantially equal to the outer diameter of the upstream end of the valve103where the valve103and poppet112mate.

The first inner poppet diameter portion and the intermediate inner poppet diameter have a tapered connection. The intermediate inner poppet diameter portion and the third inner poppet diameter portion for an annular surface which is expanded radially to form a groove within the poppet bore114with a diameter greater than the third inner poppet diameter and the intermediate inner poppet diameter. The groove accepts an O-ring seal116, where the inner diameter of the O-ring seal is smaller than the third inner poppet diameter and the intermediate inner poppet diameter.

The poppet112includes ventilation passages128which extend through the main body of the poppet112and form a substantial ring around the circumference. In one disclosed embodiment, the ventilation passages128exist in pairs on opposed sides of the poppet112. In another disclosed embodiment, multiple sets of ventilation passages128are provided in the poppet112. The ventilation passages128are in fluid communication with the poppet bore114. The poppet112further includes female straight threads148at the upstream end. The female straight threads148accept male straight threads125of the retainer plug124. In one disclosed embodiment, the poppet is formed from stainless steel, however, a wide variety of materials may be used to form the poppet without detracting from the spirit of the invention, including but not limited to brass.

The retainer plug124includes a bore126and pressure cavities134. The bore126extends through the main axis of the retainer plug124while the pressure cavities134extend partially through the retainer plug. The pressure cavities134extend from the upstream end of the retainer plug124, the end closest to the cylinder10, but do not extend through to the downstream end. A tightening tool (not shown) may be inserted into the pressure cavities to assist in inserting the retainer plug124into the poppet112. The outer shell of the retainer plug124is formed by the male straight threads125which mate the retainer plug124to the poppet112. A flange136extends across the diameter of the downstream end of the retainer plug124and is perpendicular to the axis of the bore126which passes through the flange136. The flange136interacts with notch138of the seat plug118. In one disclosed embodiment, the retainer plug124is formed from brass, however, a wide variety of materials may be used to form the retainer plug124without detracting from the spirit of the invention, including but not limited to stainless steel.

The seat plug118includes a base portion137and a tube portion139. The upstream end of the base portion137forms a notch138which interacts with the flange136. The base portion137diameter is smaller than the third inner poppet diameter and the retainer plug124diameter. The base portion137does not include a bore. The base portion137is fixedly attached to, or formed as a single unit with, the tube portion139forming a tapered connection.

The tube portion139includes a seat plug bore120which is bored to a diameter substantially equal to the shear tube bore108diameter. The tube portion139includes two outer diameters146,142respectively, with a tapered connection. At the downstream end of the seat plug118, the first outer diameter146is substantially equal to the diameter of the shear tube109, which is smaller than the first inner poppet diameter. The second outer diameter142has a tapered connection to the first outer diameter146and is smaller than the intermediate inner poppet diameter and is larger than the first inner poppet diameter. The tapered connection of the tube portion109is substantially equal to in length and pitch to the tapered connection between the first inner poppet diameter portion and the intermediate inner poppet diameter portion tapered connection.

The tube portion139includes ventilation passages122which extend through the tube portion139of the seat plug118and form a substantial ring around the circumference. In one disclosed embodiment, the ventilation passages122exist in pairs on opposed sides of the seat plug118. In another disclosed embodiment, multiple sets of ventilation passages122are provided in the seat plug118. The ventilation passages122are in fluid communication with the seat plug bore120, the poppet bore114and the shear tube bore108. In one disclosed embodiment, the ventilation passages122and128are correlated such that equivalent pairs of ventilation passages122and128are aligned on the same axis. In one disclosed embodiment, the diameters of the ventilation passages122and128are substantially equal.

When the valve103and the springless shear protection device101are attached to form the valve and shear protection device100, compressed gas or liquid passes through the valve and the springless shear protection device100through manual control. When the valve and the springless shear protection device are assembled, the shear tube109is fixedly attached to the valve103at annular surface111. The shear tube109extends beyond the valve103into the poppet bore114. The seat plug118is loosely disposed in the poppet bore114and is enclosed at the upstream end by the threaded attachment of the retainer plug124to the poppet112. The poppet112is threadedly attached to the valve103at the poppet's112downstream end.

In this configuration, the upstream end of the shear tube109abuts the downstream end of the seat plug118, forcing the seat plug118to abut the retainer plug124and inserts flange136into notch138. The ventilation passages128of the poppet112and the ventilation passages122of the seat plug118align and allow fluid communication of the compressed gas or liquid in the cylinder10with the seat plug bore120and the shear tube bore108. In one disclosed embodiment, the ventilation passages of the poppet112and the ventilation passages122of the seat plug118do not align. Fluid communication of the compressed gas or liquid in the cylinder10with the seat plug bore120and the shear tube bore108is accomplished as the poppet bore114is intermediate to the seat plug bore120and the shear tube bore108and is in fluid communication with both.

The compressed gas or liquid in the cylinder10places a force directed downstream on the upstream end of the seat plug118. The compressed gas or liquid of the cylinder10passes through the retainer plug bore126and abuts the upstream end of the seat plug118. However, the seat plug118remains abutted to the retainer plug124as a result of the shear tube109abutting the downstream end of the seat plug118. The upstream force of the shear tube109is greater than the downstream force of the compressed gas or liquid in the cylinder10.

In the event of a shearing of the valve103of the valve and springless shear protection device100, the shear tube109is removed as an upstream force. The downstream force of the compressed gas or liquid moves the seat plug118from abutting the retainer plug124to abutting the downstream end of the poppet bore114. The base portion137engages the O-ring116located in the poppet bore114and forms a barrier. The compressed gas or liquid entering the poppet bore114either through the ventilation passages128or through the retainer plug bore126abuts the downstream end of the seat plug118. The ventilation passages122of the seat plug118are no longer in fluid communication with the compressed gas or liquid. The internal pressure of the compressed gas or liquid maintains pressure on the seat plug118thereby forming a seal between the seat plug118and the poppet112and the O-ring116.

Referring now toFIGS. 4,5aand5b, a valve with two springless shear protection devices is shown. A valve and springless shear protection device100attaches to a relief device400. The valve and springless shear protection device100is substantially the same as disclosed above. The male straight (or tapered) threads130mate with the female straight (or tapered) threads402of the relief device400. In one disclosed embodiment, the relief device is an angle-type relief device for truck-borne high pressure gas cylinders. Examples of such an angle-type relief device are shown in U.S. patent application Ser. No. 10/141,413 entitled “Method And Apparatus For Orbital And Seal Welded Relief Device On A Compressed Gas Cylinder,” filed on May 8, 2002 by Steven K. Aderholt, Franklin B. Piehl and Dennis C. Hatfield which is hereby incorporated by reference for all purposes. The valve and springless shear protection device100is inserted into bore402at the downstream end of the relief device400. A secondary bore406is in fluid communication with bore402and is perpendicular to bore402and the main axis of the relief device400. At the upstream end of the relief device, a springless shear protection device101is attached, providing fluid communication of the springless shear protection device100with the inlet bore408, the secondary bore406and the bore402. The relief device400and the attached springless shear protection device101are attached to the cylinder10. Male straight (or tapered) threads401mate with the female straight (or tapered) threads304of the bullplug300which is attached to the cylinder10.

The relief device400includes a valve body424and a washer422, rupture disc420, shear ring418, adapter416, membrane414, and flare nut412. The valve body424includes a main body coaxial with the cylinder10and an integral riser portion425having an axis perpendicular to the main axis and the cylinder axis. The operation of the angle-type relief device400operate to relieve pressure if an over pressurization occurs.

The riser portion425of the valve body424protrudes beyond the outer diameter of the main body423. This presents yet another opportunity for shear in the event of an accident, in this case the shear of the riser and the valve body424shear from the cylinder10. The relief device400and the springless shear protection device101function as previously described. If the relief device400shears, the springless shear protection device101attached to the upstream end of the relief device400blocks the flow of the compressed gas or liquid. If the valve and springless shear protection device100shear, the downstream springless shear protection device101prevent the flow of the compressed gas or liquid.

Referring now toFIGS. 6a,6band7an alternate valve and springless shear protection device are shown. A valve600is shown attached to the springless shear protection device101. The valve600includes two outlet bores604and606. The outlet bores604and606are in fluid communication with inlet bore608. The springless shear protection device101attaches to the valve600through male straight threads132and female straight threads611. The springless shear protection device101includes the shear tube109, the seal gasket110, the poppet112, the O-ring116, the seat plug118and the retainer plug124. In this embodiment, the larger diameter of the valve600male straight (or tapered) threads610allow for direct mating with the cylinder10without the need of an intermediary bullplug (not shown). The male straight (or tapered) threads610mate with the female straight (or tapered) threads700located in cylinder bore702. The shear protection device's101diameter increase is proportional to the increase in the diameter of the valve600male straight (or tapered) threads610. However, the diameter of the springless shear protection device101may vary without detracting from the spirit of the invention. The shearing protection function occurs as disclosed above if the valve600is sheared from the cylinder10.

Referring now toFIG. 8, an exploded view of a sheared valve and springless shear protection device is shown. The valve600is sheared800from the cylinder10. When the valve600is sheared, the upstream force on the seat plug118from the shear tube109is removed and the seat plug is forced downstream by the internal force of the compressed gas or liquid in the cylinder10. The seat plug118engages the O-ring116and forms a barrier to stop the escape of the compressed gas or liquid. Barrier space802is formed between the upstream end of the seat plug118and the retainer plug124. As the ventilation passages122are moved downstream, the pressurized cylinder10contents are no longer in fluid communication with the seat plug bore120.

Other embodiments of the invention will be apparent to those skilled in the art after considering this specification or practicing the disclosed invention. The specification and examples above are exemplary only, with the true scope of the invention being indicated by the following claims.