Back pressure

Valves with a nominal opening pressure of 5 sig or lower may require back pressure to test the resealing pressure.

For example, for a valve with a rated opening pressure of 25 PSI, the actual opening pressure is between 22 and 28 PSI, and the resealing pressure range is between 16 and 22 PSI. For one-way valves with a rated opening pressure of 3psig or lower, a back pressure of up to 4sig may be required to test for resealing airtightness.
 

Testing

Each one-way valve is tested for its opening pressure and resealing pressure before leaving the factory。