Fluid handling – Ambient condition change responsive – Atmospheric
Patent
1996-02-02
1999-06-22
Chambers, A. Michael
Fluid handling
Ambient condition change responsive
Atmospheric
137 77, F16K 1738
Patent
active
059133260
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shut-off device which closes automatically at a defined threshold temperature, with a shut-off element which is held in the open position by at least one element inhibiting a closing force.
2. Background Art
In order to limit damage in the event of a fire, plant, plant sections and pipeline systems which carry combustible gases or liquids are equipped with reliably isolating shut-off devices. Through the closing of the shut-off device the flow of medium is interrupted and the uncontrolled escape of combustible gases or liquids from a damaged plant section into the downstream system is prevented.
The DE-G 76 27 697 teaches an automatically closing shut-off valve, in particular for gas pipelines. Said shut-off valve exhibits a valve housing, a valve seat between gas inlet and gas outlet and a valve closing body. Said valve closing body is held in the open position by fixation with soft solder and can be moved into the closed position by means of a spring action. In the event of a fire, the soft solder softens and causes the automatic closing of the shut-off valve.
The disadvantage of such a shut-off system is that it can only be used on small valves of one particular kind (globe valves) so that it is limited in its scope of application mainly to the field of residential gas supplies. Furthermore, its function is restricted to the direct influence of temperature on the shut-off valve itself. Plant and plant sections which are operated at high pressure normally have so-called fire-protection valves which are located in a protected position outside the plant building at a sufficient safety distance from said building and can be closed either manually or by a mechanical drive in the event of a fire. It is often not possible to place such valves at a sufficient safety distance from the plant building due to local conditions or, in particular with small plant, the cost of location at a sufficient safety distance is not economically acceptable. Here in the event of fire the actuation of the valves is severely impaired or not possible.
THE INVENTION
Therefore, the object of the present invention was to provide an automatically closing shut-off device of simple design, particularly for the high-pressure range, which closes reliably and automatically if there is an unusual rise in the ambient temperature.
According to the present invention, this task is solved by a shut-off device of the aforementioned type in that the shut-off device has, as an element for inhibiting the closing force, at least one variable-volume hollow body to which pressure is applied and which is designed as a bellows or pressure pad, and has at least one predetermined breaking piece which is made of a material whose melting temperature is set at a defined threshold temperature.
The advantage of such a closing device is that it has a simple and robust design. The shut-off device is kept in the open position by an element inhibiting the closing force. The element can advantageously be formed directly by the variable-volume hollow body to which pressure is applied whilst the closing force is produced, for example by the weight of a body at rest or a spring under tension. When the threshold temperature is reached or exceeded, the closing action is triggered by the material of the breaking piece melting and the pressure falling in the area of the predetermined breaking piece. This releases the force of pressure in the hollow body. The closing force becomes effective and can, depending on the valve design, act directly on the shut-off element or indirectly trigger the closing action via an actuating device so that the flow of combustible fluid is interrupted.
The design of the hollow body as a bellows or an elastic pressure pad has the advantage that, for example, a body acting as an actuating element can be arranged directly on the hollow body. When the pressure falls in the hollow body, said hollow body is pressed together by the weight of the body moving do
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patent: 2264677 (1941-12-01), Oxland
patent: 2288024 (1942-06-01), Persons
patent: 2893413 (1959-07-01), Nordahl
patent: 3429321 (1969-02-01), Thrall
patent: 4887630 (1989-12-01), Hill
Chambers A. Michael
Ruhrgas Aktiengesellschaft
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