Fluid handling – Destructible or deformable element controlled – Heat destructible or fusible
Patent
1996-12-20
1998-11-17
Ferensic, Denise L.
Fluid handling
Destructible or deformable element controlled
Heat destructible or fusible
137457, F16K 1714
Patent
active
058363386
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The invention concerns a thermal safety device for sealing conduits, especially gas conduits, at the occurrence of an undue rise in temperature according to the introductory part of the first patent claim.
STATE-OF-THE-ART
There are a number of forms of construction of such thermal safety devices which are installed in conduits as for example before gas fittings, gas equipment, gas meters etc. Their purpose is to interrupt gas supplies, when rises in temperature take place, before the temperature in the named gas equipments becomes so high that their external gas-tightness is endangered.
Thus a so-called fire protection valve is known from WO 93/06397 with locking spring for the automatic sealing of conduits. In this fire protection valve, a metal closure body is arranged in a housing, which has a spherical form in the sealing area with which it lies, in the open position, on three fixed points formed by two spheres and a temperature sensitive component, due to the force of a locking spring. Thereby the two spheres, which themselves are supported on a step in the housing, are displaced from each other such that they form an opening angle of approximately 90.degree.. The temperature sensitive component is attached to the inner wall of the housing opposite this opening angle.
This consists of an inwards opening recess which is attached to the inner wall by its base. Inside the radially inwards opening recess, there is a meltable body into which a sphere is pressed and which forms a clearance fit with the recesses opening. This makes up the third fixed point and is dimensioned such that it is almost completely within the recess when the meltable body is not in place. The seat diameter, formed by the three fixed points, for the metal closure body is thus dimensioned such that the closure body, if the sphere is located within the recess, is pressed through the resulting enlarged opening between the three fixed points due to the effective force of the locking spring.
As can be very well recognized in the corresponding FIG. 1, this solution is disadvantageous in that the eccentrically supported closure body is not axially guided in performing its closure movement. On account of the always incomplete axial working force direction of the locking spring, due to the given tolerances, the closure movement of the spheres results in their sideways deviation. The compulsorily resulting impact and the therefore necessary centering movement in the seat use part of the kinetic energy required to achieve a force fit. This force fit is necessary however, if the thermal safety device should also still be effective at temperatures at which the locking spring already has no force.
A similar solution is also described in EP-OS 574 677. With this safety gas socket, a retaining ring is supported within the housing, in or upon which an axially symmetric closure component rests, whose largest external diameter is only a little larger than that of the inner diameter of the retaining ring. Thereby the closure component is pressed by a spring element against the retaining ring in the direction of a sealing seat. The retaining ring consists of a material, which at a particular pre-determined temperature, softens so much that the closure component is pressed through the retaining ring by the spring element and in connection with a seat, blocks the gas flow.
Although with this solution an axial seating in the open position is achieved, due to the lack of axial guidance of the sphere, this solution can also not prevent the sideways deviation of the closure body as described above and its corresponding disadvantage as already mentioned.
A further thermal safety device with the same disadvantage is given in DE-GM 90 17 534. In this version, a pre-tensioned sealing ball is arranged in he housing with a retaining bolt against a compression spring. Whilst the retaining bolt is attached at one end to the sealing ball, it is supported at its other end, the diameter of which is enlarged, on a meltable body, the retaining bolt pro
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Farid Ramyar
Ferensic Denise L.
Mertik Maxitrol GmbH & Co. KG
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