Leakage in solenoid valves are classified as external and internal. External leakage is generally easy to identify and eliminate. The majority of external leakage comes from degraded O-ring seals, either worn out from usage or incorrectly installed. The solution to eliminate this leakage is to correctly install a new O-ring.
Besides incorrect installation, solenoid valve leakage might also be caused by abnormalities in solenoid valve internal pressure. Users should not ignore the maintenance of the solenoid valve to avoid leakage after using it for a period of time.
Another common mistake in leakage testing of solenoid valves is to use the wrong fluid during testing. For example, a valve that is designed to handle a liquid should not be tested with a gas. The seat design of a valve to handle a fluid is different than one designed to handle gas.
Solenoid valves that use diaphragms as a sealing member can also experience external leakage via wicking through the diaphragm. Wicking is a process whereby the pressurized fluid journeys through the diaphragm material between the rubber and reinforcing material of the diaphragm.
If the solenoid valve spring is not reasonably installed or it is deformed or its service life expires, the solenoid valve cannot work normally or leakage might occur. The solenoid valve spring is essential for the automatic resetting of the solenoid valve while it is operating.
Moreover, if “zero” leakage is present, this value should be used to correct the true leakage on the solenoid valve; this correction is important because acts directly on the acceptance or rejection of the tested valve.