Customer
Our client is a global expert in filtration technology. They design, develop and manufacture filtration and fluid control devices.
Tested product
Automotive filters
These filters ensure that the oil in a vehicle's engine is kept clean.
Objective
The leakage test bench is used to validate the conformity of the filter under test according to a defined test protocol.
Problematic issues
An air filter is designed to let air through while trapping impurities. In order to ensure that the filter is well filtered and that there are no holes, the test consists of pressurising the inside of the filter with a precise pressure and ensuring that no air passes through (small leak).
The difficulty lies in detecting the leak. As a filter is "soft", a flow measurement would not be revealing (the filter inflates under pressure).
Immersing the filter allows the presence of bubbles to be detected when pressurised and therefore a leak. To detect bubbles, it is necessary to use a surface tensiometer, which can detect disturbances on the surface of a fluid.
Solution and result
The equipment studied by our teams is an air leakage test bench by immersion. The unit consists of a stainless steel frame topped by a polycarbonate tank.
A mirror is placed at the bottom of the tank to allow simultaneous observation of both sides of the filter under test.
The part to be tested is fixed, in the tank, on a rotating support. This allows the filter to be turned over without having to dismantle it. A level sensor mounted on the filter support allows the measurement of the water level above the filter.
The system is designed to operate with demineralised water.
Compressed air is supplied via the air network. A filter upstream of the circuit prevents impurities in the test air circuit. A pneumatic valve controlled by a pneumatic distributor opens and closes the pneumatic test circuit.
A temperature sensor monitors the water temperature. A level sensor measures the depth of the filter in the water.
The water tension is measured outside the tank via a tensiometer. The accuracy values measured are recorded on a PC. These measurements are used to check the conformity of the test conditions according to configurable criteria (for example: temperature between 17 and 27°C).
