Fluid handling – Destructible or deformable element controlled – Heat destructible or fusible
Patent
1998-09-02
2000-02-01
Rivell, John
Fluid handling
Destructible or deformable element controlled
Heat destructible or fusible
137 79, F16K 1738
Patent
active
060191198
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention concerns a thermal safety device for automatically blocking pipes, especially gas pipes, if an inadmissible rise in temperature should occur, in accordance with the characterizing clause of the first patent claim.
Such thermal safety devices, installed in pipes, for example in front of gas fittings, gas appliances, gas meters, etc., are available in a variety of designs. Their function is to interrupt the gas supply when there is a rise in temperature before the temperature on the appliances mentioned increases to such an extent that their external sealing is endangered.
In DE-OS 44 22 241, for instance, a thermal valve safety device is described of the type mentioned at the beginning. With this solution there is a closing element in the axial continuation of a seat located within the casing. This closing element is kept in the open position by at least one molding bent approximately into a U-shape. Following a sealing area facing towards the seat, on the side facing away from the seat the closing element forms a throat, to which a preferably cylindrical collar is attached. Both the legs of the molding are therefore located within the area of the throat and thus form a rest for the collar against the force of the closing spring. Furthermore, the part of the molding which links both the legs is propped on a thermal solder element, which is itself adjacent to the internal wall of the casing. Once the thermal solder element has melted away, the legs of the molding, because the molding has consequently changed its position in the casing, are no longer within the throat of the closing element. Under the influence of the closing spring the closing element thus moves to the closed position. Thereby each of the legs forms a guideway directed towards the seat for the collar and/or the sealing area of the closing element.
This solution has the drawback that the casing next to the closing element has many fittings, particularly in the circulation cross section of the closing element. In order to achieve standard specifications or the flow values desired in practice, for example, one is forced to determine the dimensions accordingly, and, as a result, similarly required and/or desired minimal dimensions, especially for installation, cannot be fulfilled.
Furthermore, in EP-PS 605 551 there is a so-called fire-protection valve with a closing spring for automatically shutting off pipes.
With this fire-protection valve a metallic closing element is aligned in a casing. In the sealing area the closing element has a spherical form, with which, under the force of a closing spring, it rests in the open position on three fixed points formed by two balls and a temperature-sensitive component. Both balls, which are themselves propped on a rest in the casing, are at such a distance from each other that they form an acceptance angle of approx. 90.degree.. Opposite this acceptance angle the temperature-sensitive component is secured to the internal wall of the casing.
The component consists of an inwardly-open cup, the base of which is secured to the internal wall. The radially inwardly-open cup contains a solder element, into which a ball forming a clearance fit with the opening of the cup is pressed. The ball forms the third fixed point and is sized so that it is located almost entirely within the cup once the solder has melted. The three fixed points form the diameter of the rest for the metallic closing element, and its dimensions are such that, when the ball is in the cup, the closing element is pushed by the force of the closing spring through the enlarged opening resulting between the three fixed points.
FIG. 1 accompanying this device demonstrates clearly that the drawback of this solution is that the eccentrically positioned closing element is not guided axially when the closing stroke is carried out. The force direction of the closing spring is never perfectly axial because of the existing tolerances, and so in the closing stroke the ball is deflected sideways. The in
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Mertik Maxitrol GmbH & Co. KG
Rivell John
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