There are two methods for air tightness test of pneumatic actuator. The first method is to cut off the gas source with a cut-off valve after the test gas pressure of the actuator reaches the test pressure, and observe and test the change of gas pressure in the membrane head. In the specified time, the drop of gas pressure is not allowed to exceed the specified value. The second method is to apply soapy water to each seal after the pressure of the test air chamber of the actuator reaches the test pressure, and no leakage bubbles are allowed.

During the test, the seals to be checked are:

1, the seam between the upper and lower membrane covers and the membrane is sealed;

2. Joint sealing between plug, tray and film;

3. Sealing of each O-ring;

4, the air chamber wall, the welding point.

According to the national standard GB/T42 13-92, under the rated air supply pressure, the pressure drop of the inner film air chamber is not more than 2.5Kpa within 5 minutes, and the pressure drop of each air chamber of the cylinder is not more than 5Kpa.