Cross Connection Practice Exam

What happens if the high side bleed needle valve is left open during a field test of the check valve on a Pressure Vacuum Breaker Assembly?

1. Increase the pressure between the check valve and the shut off valve

2. Reduce the pressure between the check valve and the #1 shut off valve

3. Create a vacuum effect in the system

4. Allow for unrestricted water flow

The correct answer is: Reduce the pressure between the check valve and the #1 shut off valve

When the high side bleed needle valve is left open during a field test of the check valve on a Pressure Vacuum Breaker Assembly, it leads to a reduction of pressure between the check valve and the #1 shut off valve. The purpose of this bleed valve is to allow air to escape from the system, which helps in maintaining the proper operational conditions. When the bleed valve is open, it essentially creates an additional pathway for air to enter the system, thereby preventing the build-up of pressure in that segment of the plumbing system. This situation effectively reduces the pressure in that area, as the introduction of air diminishes the likelihood of creating a vacuum that would ordinarily occur if water were to try to flow back into the system. In a properly functioning installation, maintaining appropriate pressure levels is crucial for ensuring that backflow prevention devices, like check valves, operate correctly to avoid contamination of the potable water supply.