Necessary duration of test cycles
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Of course, efforts to keep the cycles as short as possible.This must,
however, ensures that the test results the appropriate test reliability (see
also the capability study) have. Cycles are too long, possibly to use a separate
testing station operating in parallel may be necessary. The more expensive of
course, the entire inspection system and ultimately the product being
tested.
A complete test cycle in leak test and flow test systems is always much
the same principle:
- Filling of the test volumen by the nominal test
pressure (filling phase)
- Wait until all transient processes are completed (calming phase)
- Finding the leak by means of differential pressure and mass flow processes
(measurement phase)
- Issue and evaluate the results
- Venting the test volume (exhaust phase)
The duration of each phase depends very much on the test conditions. These
include, for example:
- The required test pressure
In general, the
test cycle with increasing pressure is a little longer, because here the
compensation processes in the test gas (air) may take longer.
- The required limit leakage
To obtain a stable
process, must be achieved a reproducibility, which is less than 10% of the
marginal leakage. However, since all measurement systems (sensors) have a
finite resolution, one can only reach by extending the measurement time to
produce the desired results. Under certain circumstances, eg one is forced to
specific inspection tasks that come too close to reality by a different
approach.
- The examined test volume
The volume structure
(surface, material, etc.) also contribute, as long as the filling, comforting
and measurement phase should be interpreted. Simple cavities usually require
longer cycles than a jagged hole system. Also, metal parts behave differently
than plastic parts.
- The possible influence of temperature
Each
temperature control during test affects the final result. Here it is to check,
that you see an constant influence. This mostly is easy to compensate.
Otherwise it may be necessary to use a temperature compensation
system.
APT has a long experience in the field of leak and flow test. The best way is
therefore to give the entire test APT known. We then choose the appropriate test
system for the inspection task with the necessary accessories for our customers
and deliver targeted at the corresponding site.