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Other Types of Leak Detection
Acoustic
Leak Detection uses sonic or ultrasonic energy that
is
generated by a gas as it expands through an orifice. This
method is
fairly simple and fast but is only sensitive to 10-3
atm
cc/second.
Bubble
Testing is a common method of leak detection in industry
today.
Bubble Testing
can be as simple as pressurizing a part, placing it under
water, and
looking for leaks. It can also be done by pressurizing
the part
with air, applying a soapy solution, and looking for
bubbles.
Bubble Testing is simple and cost effective for locating
large leaks
but also has its drawbacks. The test piece gets wet
and may
therefore need drying. It also cannot measure total
leakage
rates and is only useful for 10-4 atm cc/second leaks and larger.
Example:

Mass
Flow Leak Detection is used to as an alternative to pressure decay.
Using the
Apex Vacuum Mass Flow Controller leaks can be found as
low a 1 x
10EE -03 mbar l/sec. The test vessel is pressurized to a known pressure.
Using a
Apex Pressure Controller, the pressure can be kept at a constant in the
supply
gas line.
Thus any make up gas would be measured on the Apex Mass Flow
Controller.
Pressure
Decay is commonly used in plumbing and many other
industries.
Pressure Decay Testing may only involve a compressor and a pressure
gauge,
though some systems can be much more complex and
expensive.
The sensitivity of the Pressure Decay Testing method is proportional to
time but
generally limited to 10-4 atm cc/second. Another
problem
with this method is that fluctuations in temperature degrade the
accuracy of the tests.
Halogen
Gas Detection is commonly used in the air conditioning
and cooling
industry. This technology uses an infrared type
detector to
detect the presence of halogen tracer gas. This
requires
the test piece to be charged with Halogen, which is
impractical,
expensive, and can be an environmental issue |