During a field test, where is the vent screw located in relation to a Pressure Vacuum Breaker Assembly check valve?

The vent screw in a Pressure Vacuum Breaker Assembly check valve plays a crucial role in maintaining the function of the device during testing. When conducting a field test on such an assembly, the vent screw must be completely removed to allow for proper venting of air from the assembly. This removal is vital because it enables the check valve to properly function by preventing the potential for back siphonage and ensuring that the assembly can bleed off any pressure that might affect its operation.

During the test, if the vent screw remains in place, either partially tightened or loosely fitted, it may not allow air to enter the assembly appropriately, leading to inaccurate test results. Therefore, for the test to simulate normal operating conditions and accurately assess how the device reacts under backflow conditions, the vent screw must be removed entirely. This ensures that the assembly can perform as intended without any obstructions.