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When setting the limits of allowable leakage, it is always necessary to set
a practical leakage level for the product under testing. Decreasing the
permissible leak rate below a practical level and increasing the sensitivity
of the required test method only brings with it an unnecessary increase in
the time required and the cost of performing a test.
Leak testing is divided into two general categories, Leak Measurement
and Leak Location.
Leak Measurement is the quantified assessment of an object's or systems
leak rate and is also the preferred method of determining that a leak does
exist. Leak Location is the procedure of pinpointing the precise location
of individual leaks. When testing an object, the most reliable sequence is
to first measure the total leakage of a test object, and then, if necessary,
determine the location of individual leaks.
A leak rate specification should take into account the effect of leakage on the
system and its application. Long-term storage of the object or system may be
necessary and should be considered when creating a leakage standard.
Any leak detection procedure requires careful planning. Ample
consideration to test sensitivity and response time is required when testing
any object. At times, it may be preferable to specify a maximum tolerable
leakage rather than specifying a maximum allowable leak rate. The
maximum tolerable leak rate may be calculated by multiplying the
maximum allowable leak rate by the length of time a system or object is
expected to be used (including storage time). If a gas or liquid is not
introduced to the system or object until it becomes operational (at some
future date), the maximum tolerable leakage need only be specified for the
duration of its operation. The level of the maximum tolerable leakage
should always be specified when the total amount of leakage is more
important than the leak rate.
A commonly used method for determining the maximum allowable leak
rate is derived from the consideration of leaks in the following situations:
Vacuum Instrument Corp.
Vacuum Instrument Corp.
2099 Ninth Avenue
2099 Ninth Avenue
Ronkonkoma, NY 11779
Ronkonkoma, NY 11779
631.737.0900
631.737.0900
1109-186-00 Rev. C
•
To prevent the loss of contained gases or liquids
•
To prevent hazards caused by escaping toxic materials
•
To prevent contamination due to materials leaking from or
leaking into an object
•
To test the projected reliability of sealed systems or the
components within the systems.
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