Measuring and testing – With fluid pressure – Leakage
Utility Patent
1998-09-14
2001-01-02
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S049600, C073S040000
Utility Patent
active
06167749
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a method and apparatus for automatically detecting gas leak in a valve on a gas-containing vessel, etc. or a connector, and a recording medium storing a program for the automatic gas leak detection.
b) Description of the Related Art
For example, Laid-open Japanese Patent Application No. Hei 3-89100 discloses a method for automatically detecting gas leak in a valve on a gas-containing vessel. According to the conventional method, detection of gas leak is based on measured pressure fluctuation of helium gas which is filled in an airtight room communicating with a valve on a gas-containing vessel.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved gas leak detection method or an apparatus which can automatically detect both fine gas leaks and gross gas leaks, and a recording medium storing a program for the automatic gas leak detection.
According to an aspect of the present invention, there is provided a method for automatically detecting gas leak in a target object provided on gas piping, which comprises the steps of: forming an airtight room communicating with said target object; pressurizing said airtight room to a predetermined pressure; measuring absolute pressure and pressure fluctuation of said airtight room; and determining whether gas leaks in said target object or not based on the measured absolute pressure and pressure fluctuation.
According to this method, gas leak is detected regardless of the leakage rate, because of detecting both the pressure fluctuation and absolute pressure in the airtight room.
According to another aspect of the present invention, there is provided a method for detecting gas leak in a valve provided on a gas-containing vessel comprising the steps of: forming an airtight room communicating with said valve; evacuating said airtight room; measuring absolute pressure and pressure fluctuation of said airtight room while keeping said airtight room hermetic after the evacuation is stopped; and determining whether gas leaks in said valve or not based on the measured absolute pressure and pressure fluctuation.
According to this gas leak detection method, both the absolute pressure and pressure fluctuation in the evacuated airtight room are measured. Then, seat leak in a valve is detected based on the measured absolute pressure and pressure fluctuation. Since the absolute pressure of the airtight room rapidly increases when the gas leaks in the valve on the gas-containing vessel at a high leakage rate, gross leak is detected based on the measured absolute pressure. Since the pressure of the airtight room increase slowly and gradually when the gas leaks in the valve on the gas-containing vessel at a low leakage rate, fine leak is detected based on the measured pressure fluctuation. Therefore, the seat leak is detected without failure regardless of the leakage rate.
According to a further aspect of the present invention, there is provided a method for detecting gas leak in a connector detachably connecting a gas pipe from a valve on a gas-containing vessel, comprising the steps of: forming an airtight room communicating with said connector and with said valve via said gas pipe; evacuating said airtight room; introducing gas into said airtight room after the evacuation is stopped; measuring absolute pressure and pressure fluctuation in said airtight room filled with said gas while keeping said airtight room hermetic; and determining whether gas leaks from said connector or not based on the measured absolute pressure and pressure fluctuation.
According to this gas leak detection method, absolute pressure and pressure fluctuation in an airtight room filled with gas are measured, and it is determined whether the gas leaks in a connector or not based on the measured absolute pressure and pressure fluctuation. In the case where the gas leaks from the connector at a relatively large leakage rate, the absolute pressure of the airtight room reduces rapidly, and the absolute pressure equals to the atmospheric pressure eventually. Therefore, the gas leak whose leakage rate is relatively large (gross leak) is detected based on the measured absolute pressure. On the contrary, if the gas leaks from the connector at a relatively small leakage rate, the pressure of the airtight room reduces gradually. Therefore, the gas leak when leakage rate is relatively small (fine leak) is detected based on the measured pressure fluctuation. Accordingly, the method can detect gas leak without failure regardless of the leakage rate.
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Hirota Naoshi
Yanagisawa Takahiro
Ostrolenk Faber Gerb & Soffen, LLP
Wiggins David J.
Williams Hezron
Yamaha Corporation
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