In the atmospheric pressure method, the work is positioned at the air pressure source side and the laminar at the atmospheric pressure side. It is used mainly for valve and other areas where the leak location is specified.
The test pressure is supplied to the work and the leaked air passes through the laminar and it is exhausted into the atmosphere. The flow rate can be obtained by multiplying the pressure difference at the laminar by the laminar coefficient. The same laminar coefficient can be used when the test pressure is changed.
When there are multiple leak locations or when the leak location is not specified.
In the line pressure method, the laminar is positioned between the air pressure source side and the work at the atmospheric pressure side. It is used for assembly parts of engines and other products.
The test pressure passes through the laminar and is supplied to the work and is exhausted into the atmosphere. The laminar coefficient in this method depends on the test pressure.