What Are The Basic Principles Of Leak Testing?


Leak testing is detecting gas or liquid leaks caused by manufacturing defects, such as cracks or rotten seals in an object. The gas or liquid flow is always from the higher to the lower pressure. Leaks are detected when gas or liquid flows from positive pressure inside the object to negative atmospheric pressure outside the thing. In rare cases, a leak can flow from the opposite direction inside the entity to the atmosphere.

Leak testing is used to detect the undesired porosity in an object. It is also a quality control measure to guarantee product integrity. Technical products such as pressure vessels, TV, Cathode Tubes, Chemical or Nuclear Plants, pumps, beverage cans, etc. require hermetically sealed elements. When manufacturing such products, it is necessary to control the external atmosphere from under or over pressure by ensuring the product is tightly sealed.

The principles of leak testing

Leakage can be caused by two factors – difference in pressure and pressure change.

Difference in pressure

The quantity of air per volume is determined by atmospheric pressure. When atmospheric pressure is very high, the air is very high. To balance atmospheric pressure, air flows from high to low point. Because of this principle, the stand is made to move at different pressures to detect leaks.

Change in pressure

The air inside the object is charged to increase the pressure inside the thing, resulting in a difference in tension between inside and outside the object. If an object has a defect, the air inside will move to the outside. Changing the air pressure inside the thing helps maintain the traction of leaks.

Methods of leak testing

Internal pressure change method

This method involves keeping track of the difference in pressure after applying pressure within the object over time. This method is most suitable for an object with an air charging port and a low degree of deformability.

External pressure change method

This method involves placing the object and the masterwork in the chamber. The pressure in the room is applied in the volume between the object and the classic. The object’s internal pressure change is caused by air intrusion within the thing. This method is most suitable for objects with no air charge port and a low degree of deformation.

Tank pressuring method

In this method, the pressure inside the object is applied using compressed air in a tank. This method can be used on things that do not have a pressurization port and have a relatively large internal volume. The main leak testing applications include leak testing on ships, automotive components, medical devices, industrial products, and packaged foods and beverages.


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