Apparatus and method for leak test
View Patent ↗An apparatus for leak test is provided with: a gas dissolution portion having function to degasify a unused liquid; a liquid filling and circulation portion for filling the gas dissolved liquid in the test piece; a high-pressure application portion for pressurizing the filled gas dissolved liquid; a leak test portion for detecting the gas in the liquid vapor leaking out in the vacuum container from leak hole(s) of the test piece resulting from high-pressure application; and a liquid collection portion for collecting the gas dissolved liquid as relieving high pressure. The leak test process under high pressure is conducted in the closed circulated flow path. The leak test process uses the liquid easy for gas to be dissolved and to flow through the leak hole(s). Further, the leak test process uses the gas easy to dissolve in the liquid or to be detected.
1 . A method for leak testing using, as a trace fluid, a gas dissolved liquid to conduct a leak testing of a test piece,
wherein the test piece is placed in a middle of a closed circulated flow path which goes out from a dissolution tank where the gas is dissolved at a given constant concentration, to return back to the dissolution tank through a collection tank which stores the trace fluid flown out of the test piece; and the trace fluid is processed by a degasification process of removing other gases except said gas from the gas dissolved liquid; and
wherein the trace fluid is processed by a filling process to flow from the dissolution tank through an interior of the test piece along the closed circulated flow path to be filled in the test piece after the degasification process.
2 . The method for leak testing as set forth in claim 1 wherein the test piece is placed in an interior of a vacuum container whose interior can be under vacuum condition.
3 . The method for leak testing as set forth in claim 1 wherein the interior of the test piece is put under vacuum condition in advance before being filled with the trace fluid.
4 . The method for leak testing as set forth in claim 1 wherein, before being filled with the trace fluid, the interior of the test piece is previously put under non-vacuum condition equal to or less than a gas dissolution pressure which allows the gas to be dissolved in the liquid.
5 . The method for leak testing as set forth in claim 1 wherein the test piece filled with the trace fluid is configured to be vibrated, kept still or repressurized by the gas.
6 . The method for leak testing as set forth in claim 1 wherein the trace fluid is configured to be returned back to the collection tank in the closed circulated flow path until a given time has passed since the trace fluid got started to be filled in the test piece.
7 . The method for leak testing as set forth in claim 6 wherein the trace fluid is, after the given time passed, configured to be filled in the interior of the test piece by being made passed and circulated through the interior of the test piece in the closed circulated flow path.
8 . The method for leak testing as set forth in claim 1 wherein, before the test piece is filled with the trace fluid, an upper space over a liquid level of the dissolution tank or the collection tank is drawn in vacuum condition and a degasified liquid is transferred to the interior of the test piece from the dissolution tank or the collection tank.
9 . The method for leak testing as set forth in claim 1 wherein a filling line system for filling the trace fluid in the test piece is configured to be independent of a pressurizing line system for pressurizing the filled trace fluid.
10 . The method for leak testing as set forth in claim 1 wherein a headspace over a liquid level of the liquid is drawn a vacuum while the liquid stored in the dissolution tank or the collection tank is circulated so that a part of the liquid in the dissolution tank or the collection tank is transferred to a container being under vacuum condition, to determine whether or not the degasification process in the dissolution tank or the collection tank is completed on the basis of a height of the liquid level of the liquid in the container.
11 . The method for leak testing as set forth in claim 1 wherein a headspace over a liquid level of the liquid is drawn a vacuum while the liquid stored in the dissolution tank or the collection tank is circulated so that the dissolution tank or the collection tank is communicated with a container storing the liquid completed the degasification process, to determine whether or not the degasification process in the dissolution tank or the collection tank is completed on the basis of a difference of liquid levels between the container and the dissolution tank or the collection tank.
12 . The method for leak testing as set forth in claim 1 wherein the liquid is satisfied with a following expression:
[(density of the liquid)×(solubility of the gas to the liquid)]/[(viscosity coefficient of the liquid)×(molecular weight of the liquid)]>(a given coefficient with respect to the gas)×[(density of water)×(solubility of the gas to water)]/[(viscosity coefficient of water)×(molecular weight of water)].
13 . The method for leak testing as set forth in claim 1 wherein the gas is carbon dioxide (CO 2 ) or inert gases including helium and argon belonging to the 18 th group element.