Which systems or components
would require the greatest precautions and special
considerations when preparing for a leak test?
Sintered material components
Pressure change leak testing is dependent on three
variables. A change to any of these three will have a direct
effect on at least one of the other two variables. These
three variables are:
pressure, volume, and temperature.
Which of the following is an LT technique?
Detector probe
Which LT techniques can reliably quantify
a leak ≤1.0 × 10–7 atm cc/sec in a normal industrial
environment?
Mass spectrometer leak testing
Establishing differential pressure between the test object
and the environment is an essential element in which of
the following NDT methods?
Leak testing
Which of the following best describes the LT technique
in which the interior of the test object is continuously
evacuated during the test, a tracer gas is applied to the
exterior, and a leak detector is connected to the vacuum
system?
Dynamic leak test
Assuming no significant leakage in a constant-volume
system, if the temperature increases during a pressuredrop
leak test, the pressure in the system will:
increase.
If the sensitivity of a halogen leak detector remains
constant throughout a test, and the pretest and posttest
calibrations are acceptable, which of the following
conclusions can be made at the end of the test?
The instrument and the test procedure were capable
of detecting leakage of a certain size during the test.
d. The instrument and test procedure were only capable
All leak detection techniques are dependent upon:
establishing a differential pressure across the test
boundary.
In high-vacuum systems, the sensitivity of a pressure
change leak test depends not only on the observed
pressure change but also on the degree of outgassing.
Outgassing is best defined as:
the release of gas from materials in a vacuum.
What is the essential information that must be recorded to
perform a pressure change leak test?
Temperature, elapsed time, volume, pressure
What is the easiest way to increase sensitivity in a pressure
change leak test?
Increase test time.
When performing a helium mass spectrometer hood
test, using a 50% helium concentration (instead of 100%
helium) will ________ the final measured leak rate for the
test item.
decrease
In a pressure-change “rate-of-rise” test (vacuum decay
test), which test variable is NOT recorded?
Temperature
In a helium mass spectrometer leak test using the hood
technique, if the inspector has a final calibration 40%
greater than the preliminary calibration, what would they
do?
Recalibrate and repeat the test on the item.
Which safety precautions is most
important when performing leak testing on pressurized
vessels or piping?
Stand clear of potential pressure release paths and
wear appropriate protective equipment.
Which leak test technique is well-suited for locating leaks
in low-pressure fluid containment vessels (such as lowpressure
tanks or piping)?
Bubble leak testing (soap solution applied over slight
pressure or vacuum)
What technique is typically used to detect fine leaks in
hermetically sealed components (such as electronic
packages)?
Helium mass spectrometer leak testing
