Safety valve with meltable sealing disc for a gas cylinder

Abstract

Valve for a gas container (25) such as a gas cylinder or gas tank, with a gas outlet channel (9) that can be opened and closed, wherein the valve is a safety valve (15) and includes a further gas outlet channel (16) that can be closed by a sealing device comprising a material that melts upon reaching a critical temperature, allowing gas to escape from the gas container (25). The sealing device is characterized in that it is a sealing disc (17) that is received in a spring retainer (18) which is pressed into the closed position of the sealing disc (17) by a helical compression spring (19), the helical compression spring (19) being supported against a cap (21) screwed into the end region of the associated lateral projection (20), wherein the sealing disc (17) consists entirely or partially of the material that melts upon reaching the critical temperature.

Description

[0001] The invention relates to a valve for a gas container, such as a gas cylinder or a gas tank, according to the preamble of claim 1. The valve preferably has a thread with which the valve is screwed into the gas container. The valve can also be attached to the gas container in another way, for example, by being tightly screwed to the gas container using screws.

[0002] The gas container can be, for example, a fuel gas cylinder or LPG cylinder, which are available in various sizes, or a gas tank, which can be held upright in a mobile home, for example, or arranged horizontally on a forklift or stationary engine. These can be small or large gas containers, and the use of the valve according to the invention is not limited to any size.

[0003] Very common gas cylinders have a net weight of approximately 11 kg or 14 kg and are filled with liquefied gas consisting of propane or butane, or a propane / butane mixture. Such fuel gas cylinders are used for a variety of household and commercial purposes. The gas from such cylinders can be used in its gaseous phase for a variety of household or commercial purposes, or in its liquid phase, for example, to power engines.

[0004] Gas cylinders of this type are often made of steel, which makes them considerably heavy. Gas cylinders made of suitable aluminum alloys are now also common, some of which are even corrosion-resistant and, due to their significantly lower weight, are always much easier to handle. There are also no restrictions on the material used for the gas cylinders regarding the valve.

[0005] Gas cylinders are subject to very strict safety requirements, as they can cause devastating damage if they burst or explode. In a burst, the cylinder "merely" ruptures; in an explosion, it shatters into several flying pieces, acting like projectiles. If a cylinder bursts in a mobile home for whatever reason, the bursting will shatter the mobile home into pieces. An explosion has the same effect, but also sends its components flying like projectiles. The same thing happens if a cylinder bursts or explodes in the enclosed spaces of a house. A single-family home is razed to the ground.

[0006] If a bottle bursts outdoors, it can also have devastating consequences, especially if people are nearby. Depending on how and where the bottle bursts, it will fly into the air or fly sideways. If a bottle explodes outdoors, the pressure wave causes enough damage, but the flying fragments into which the bottle breaks can have catastrophic effects. In war, they can even be used as bombs.

[0007] When cylinders are ruptured to check whether they meet legal requirements, this is done not with gas or air, but with water. The cylinder is filled to the brim with water, and then more water is injected under pressure into the already filled cylinder, continually increasing the internal pressure until it finally bursts.

[0008] If the gas cylinder is equipped with a safety valve rather than a simple valve, this opens when a predetermined internal pressure is reached, allowing gas to escape until the pressure drops below this critical pressure, at which point the safety valve closes again—generally under spring pressure. If the safety valve functions properly, this can prevent the gas cylinder from bursting due to internal pressure alone.

[0009] The situation is different if the gas cylinder is exposed to high external temperatures, as a result of which the internal pressure constantly rises to such an extent that the cylinder may burst. The situation is even more dangerous if a fire has broken out in the vicinity of the gas cylinder. In this case, there is a very high risk that the gas cylinder will explode, which in practice often makes extinguishing efforts more difficult or even impossible in order not to endanger the firefighters called out. In such a case, if the gas cylinder has a simple valve that does not allow controlled pressure relief, the heat exerted on it can cause the gas pressure in the cylinder to rise so high in a very short time that the gas cylinder explodes. This can also happen with a gas cylinder that has a safety valve that initially allows almost all of the gas to escape until it closes again below the critical pressure limit - usually 30 bar.The remaining gas in the cylinder can no longer develop the excess pressure that would cause the safety valve to reopen and allow the remaining gas to escape. However, the heat quickly reduces the pressure resistance of the gas cylinder to such an extent that an explosion can occur despite the safety valve, since even an internal pressure below 30 bar can have devastating effects in this case.

[0010] To date, gas cylinders with either a simple valve or a safety valve are not fireproof, so that in the event of a fire or other exposure to high heat on the gas cylinder, there is a major safety problem.

[0011] DE 32 45 618 A1 discloses a liquefied gas tank with an annular defusing device made of a fusible alloy, which is clamped between the lid and the tank's pipe socket. The defusing device and the pipe socket are dimensioned such that when the defusing device melts, the pressure is reduced so significantly that an explosion of the tank can be ruled out with certainty.

[0012] DE 10 2010 011 878 A1 discloses a safety device for a container subjected to gas pressure, in which an annular melting body is enclosed on all sides, so that it takes a longer time until the flow path of the gas is released when the critical temperature is reached.

[0013] FR 2 789 750 A1 discloses a liquid gas tank having washers made of a fusible material.

[0014] DE 80 34 293 U1 discloses a device for extracting gas, which includes a high-pressure container with a main valve, a low-pressure safety valve, and a backflow prevention valve. The gas is CO2 gas for supplying carbon dioxide to devices that dispense carbonated beverages.

[0015] US 2005 / 0 167 453 A1 discloses a valve with a spherical sealing surface that is pressed against a Teflon or Neoflon sealing disc by the force of a spring to seal a hole passing through the sealing disc. The sealing disc is deformed according to the spherical sealing surface, sealing irregular surfaces and preventing gas escape.

[0016] The present invention is based on the object of providing a solution to the above problem.

[0017] This problem is solved by the features of patent claim 1.

[0018] Advantageous embodiments of the invention are characterized in the subclaims.

[0019] The invention provides that the valve is a safety valve equipped with a sealing device that melts when a predetermined critical temperature is reached, allowing all the gas to flow out of the gas container. This ensures that no dangerous overpressure can develop in the gas container when exposed to heat, which could lead to the container bursting or even exploding. Thus, a gas container with the valve according to the invention is fireproof or fire-resistant. As long as a gas container with a safety valve is not exposed to this critical temperature, its safety valve functions as intended.

[0020] The invention further provides that the sealing disc is accommodated in a spring holder, which is pressed into the sealing disc's closed position by a helical compression spring, in which the helical compression spring is supported on a cap screwed into the end region of the associated lateral projection. According to the invention, the sealing disc consists entirely or partially of a fusible material that has properties such that it also fulfills the normal safety functions (opening and closing the valve). In a safety valve for gas cylinders, the sealing disc can have a thickness of 1 to 3 mm, preferably approximately 2 mm.

[0021] The temperature at which the sealing device melts should be between 100° C and 200° C, preferably between 120° C and 180° C, with a melting temperature of approximately 150° C being most preferred. However, the invention is not limited to the specified temperatures, which may be higher or lower depending on the gas container and the hazardous situation.

[0022] Further details of the invention will become apparent from the following description of two preferred embodiments and from the drawings. These show: Fig. 1 a vertical section through a simple valve not belonging to the invention in an enlarged view; Fig. 2 the valve in the screwed-in position; Fig. 3 a vertical section through a safety valve in an enlarged view; Fig. 4 the safety valve in the screwed-in position.

[0023] The Fig. 1 and Fig. The valve 1 shown in Figure 2 contains a valve body 2, the lower, slightly conically tapering shoulder 3 of which is provided with an external thread 4, with which the valve 1 can be screwed into a sleeve 24 of a gas container 25. The gas inlet channel 5 can be closed at its upper end by a plug 6, which is received in a recess of a piston 7, which can be moved upwards and downwards by a handwheel 8 in order to open or close a gas outlet channel 9 in a lateral shoulder 10 of the valve 1. For this purpose, the handwheel 8 is in threaded engagement with an internal thread 11 at the upper end region of the valve 1. The piston 7 is sealed by two O-rings 12 in the valve body 2. The reference numeral 13 designates two pins arranged one behind the other, which serve as the upper stop for the handwheel 8 and the piston 7 held by the handwheel.

[0024] The lateral extension 10 contains an external thread 14 for attaching a hose through which the gas is supplied to its destination when the handwheel 8 and thus the piston 7 with the plug 6 has released the connection of the gas inlet channel 5 with the gas outlet channel 9.

[0025] As mentioned above, the valve 1 is screwed with its external thread 4 into an internal thread of the sleeve 24 of a gas container 25. This threaded engagement is sealed by a sealing device 26, which melts upon reaching a critical temperature between 100 and 200°C, preferably approximately 150°C. The sealing device consists of a meltable sealing ring or a meltable sealing tape, or a meltable sealing paste, which reliably seals the threaded engagement below the critical melting temperature.

Claims

[1] Valve for a gas container (25) such as a gas cylinder or a gas tank, with a gas outlet channel (9) which can be opened and closed, the valve being a safety valve (15) and containing a further gas outlet channel (16) which can be closed by a sealing device which contains a material which melts when a critical temperature is reached, so that gas flows out of the gas container (25). characterized by in that the sealing device is a sealing disc (17) which is accommodated in a spring holder (18) which is pressed by a helical compression spring (19) into the closed position of the sealing disc (17), in which the helical compression spring (19) is supported on a cap (21) screwed into the end region of the associated lateral extension (20), wherein the sealing disc (17) consists entirely or partially of the material which melts when the critical temperature is reached. [2] Valve according to claim 1, characterized bythat the valve (15) is screwed into a sleeve (24) of the container (25). [3] Valve according to one of claims 1 to 2, characterized by that the sealing disc (17) melts at a temperature which is between 100° C and 200° C, preferably 120° C and 180° C, more preferably at about 150° C. [4] Valve according to one of claims 1 to 3, characterized by that the sealing disc has a thickness of 1 - 3 mm, preferably about 2 mm.

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