Fluid handling – Line condition change responsive valves – With separate connected fluid reactor surface
Patent
1995-10-10
1997-09-23
Hepperle, Stephen M.
Fluid handling
Line condition change responsive valves
With separate connected fluid reactor surface
1375133, 137517, 13761418, 13761421, G05D 1606
Patent
active
056694091
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a gas-pressure controller with a body, which has an inlet and an outlet, with a flow channel arranged between the inlet and the outlet, said flow channel having a valve seat on the outlet side and being governed by a valve disc, as well as with a valve spindle connecting the valve disc to a diaphragm.
Such gas-pressure controllers are used in low-pressure and medium-pressure applications.
When the gas-pressure controller is used in medium-pressure applications (from 100 mbar to 4 bar) it is necessary to arrange a safety shut-off valve upstream of the gas-pressure controller. The safety shut-off valve shuts off the gas supply to the gas-pressure controller automatically when the pressure at the outlet of the gas-pressure controller drops below a minimum value as a result of a shortage of gas (lower shut-off point) or when the outlet pressure exceeds a maximum value (upper shut-off point).
The fact that the safety shut-off valve has to be manually reset before the controller can be restarted is disadvantageous. This is particularly disadvantageous in the case of a shortage of gas because this occurs more frequently than too high a pressure at the outlet.
Thus, the object of the present invention was to develop a gas-pressure controller which automatically shuts off the supply of gas when the outlet pressure drops below a minimum value as a result of a shortage of gas and which automatically restarts gas supply when the minimum pressure is exceeded again.
This object is solved by the gas-pressure controller according to the present invention characterised in that an obturator disc is connected to a valve spindle on the inlet side so that it can move axially, that the obturator disc is pressed by an elastic component in the "open" direction and opens to give a flow channel provided with an obturator disc when the outlet pressure is above a minimum value and that the obturator disc substantially closes off the flow channel so that only an extremely small flow is possible when the outlet pressure falls below the minimum value.
Current safety standards require that the gas-pressure controller may only be restarted when the downstream consumers have been switched off. This requirement is met by the gas-pressure controller according to the present invention.
The safety feature for cases of gas shortage functions as follows:
When the inlet pressure drops, the outlet pressure also falls from a certain pressure onwards and the valve disc opens the flow channel more and more until the obturator disc finally closes the flow channel.
An extremely small amount of gas can still flow through the extremely small flow aperture. When the inlet pressure rises again, this extremely small amount of gas flows into the downstream pipe system. When all the consumers downstream of the gas-pressure controller are shut off, the outlet pressure can rise again and the valve disc and valve spindle lift whilst the obturator disc is kept in the closed position by the inlet pressure. Only when the valve disc moves into the closed position, can the pressure above and below the obturator disc equalise and the elastic component presses the obturator disc upwards.
A particular advantage is that a sudden passing of the inlet pressure to the outlet side is not possible. This avoids the danger of the outlet pressure temporarily exceeding the maximum pressure leading to the safety shut-off valve switching in the upper shut-off point and cutting off the supply of gas.
The flow rate of the gas-pressure controller is not substantially impaired by the obturator disc.
It is advantageous for the valve spindle to be provided with a stop for the obturator disc. With this solution the design is particularly simple.
One advantageous embodiment is characterised in that the extremely small flow aperture is designed in the form of a nozzle in the obturator disc. Thus, the extremely small flow aperture can be simply and accurately dimensioned. A flow rate of 30 litres per hour should not be exceeded.
It is advantageou
REFERENCES:
patent: 2633862 (1953-04-01), Dales
patent: 3576193 (1971-04-01), Rothfuss
patent: 4174731 (1979-11-01), Sturgis et al.
Kettner Thomas
Welker George
Elster Produktion GmbH
Hepperle Stephen M.
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