A leak basically means a hole, an unintended crack or
porosity in the enveloping wall or the joint of a covering through which various
gases and fluids accidentally pass through. The term ‘leakage’ and ‘leak’
appears in the field of vessels’ hermetical closing and doesn’t confront only
with the vacuum technologists but also engineers working with high pressures.
Nowadays, with the use of modern technologies packages are
being sealed very carefully allowing very little rates of leakage. This means
leakage in packaging still exists. It’s practically unfeasible to create a
sealed system or an enclosure, which can be guaranteed to be leakproof.
There are actually different kinds of leak sources.
Some leaks are caused by the defects in containing envelope.
For instance, a plastic bottle having a very thin wall may have a microscopic
crack at a high pressure difference.
Leaks in the newly manufactured goods can also been seen.
They are basically imperfect seals or joints by which the different parts are
assembled for forming the final product. There are the fixed joints-between
them mostly used are soldered and brazed joints ceramic-to-metal and
glass-to-metal seals, welds, O-rings etc
There may also be a virtual leak. This is special kind of
leakage in vacuum technique. It’s not actually a leakage but an internal source
of vapor or gas. These are the cavities in chamber wall having thin connections
to inner vessel space like improper welds, holes and closed threads etc.
Bag leakage detectors are used for finding out if there is
any leakage in the packaging. The main functions of a bag leakage detector are localization and measurement of the size
of the leaks in the sealed systems and products. In most of the examples, a
leak test process is the quality control step for assuring device integrity and
a one-time nondestructive examination.
Typical products where the process of leak detection is used
include vacuum chambers, cathode tubes, pressure vessels, pumps, aerosol containers,
refrigerating systems, beverage cans, nuclear and chemical plants, goods
containing metal bellows etc.
