Various Methods Of Testing For Leaks - Agilent Technologies 947 Betriebs- Und Servicehandbuch

Models 947, 948 and 960 Leak Detectors Operations and Service Manual
G.4 Various Methods of Testing for Leaks
There are many methods of testing for leaks in enclosures, systems or containers. The more
commonly used methods and their accuracy ranges are listed below:
Water Immersion
(Air Bubble Observation)
Dye Penetrant
Ultrasonic
Halogen
(sensitive to halogen elements
or compounds, especially
refrigerant gases)
Radioisotope
Helium
This method is good to approximately 10
more sensitive if internal pressure is increased or vacuum is
created above water pressure. This method is limited because of
difficulty in differentiating between leakage bubbles and surface
desorption bubbles. It is used to test industrial items such as
valves, hydraulic components, castings, automotive and air
conditioning components.
A special dye, applied to one side of a surface suspected to
contain a leak, seeps through the leak and appears on the other
side. This method can take an hour or more for a 10
leak to show up. This test is inexpensive but destructive in some
applications, as well as slow and messy.
This method is good to approximately 10
ultrasonic sounds coming from a gas leak and for testing high
pressure lines.
This method is good to approximately 10
current applications, but extendable to 10
some limited situations. It is critically dependent on operator
judgement if leaks are below 10
constant flow of fresh air in the test area because of the tendency
of trace gas to hang in the area. The detector used in this method
is sensitive to a variety of gases from external sources such as
cigarette smoke and solvent fumes.
This method is useful only for testing hermetically sealed cavities.
It has approximately the same range as the helium method but it
involves an expensive installation (from four to ten times the cost
of a helium installation depending on the degree of isolation of
radiation required). It also requires a radiation safety officer.
This method is good to 10
finding leaks of any size larger. It is useful for testing hermetic
seals, vacuum enclosures, and vacuum systems, and is the most
versatile of industrial and laboratory leak detection testing
methods.
−3
atm cc/sec, and can be
−3
atm cc/sec. It tests for
−5
atm cc/sec in most
−9
std cc/sec under
−5
atm cc/sec and requires
−11
atm cc/sec, and is capable of
−4
atm cc/sec
G-3