In a limited system with a 2 inch backflow device, what is required for forward flow testing the backflow?

• A. It is not required to measure the flow on this device
• B. 75 psi
• C. 150 psi
• D. 250 psi

Answer: (C)

Forward flow testing a backflow preventer requires enough test pressure to push water through the device as it would operate in service. For a limited-system installation with a 2-inch backflow device, the standard practice is to apply about 150 psi to the test setup during the forward-flow portion. This pressure is high enough to force the check valves to open and to reveal any leakage or improper sealing, while staying within typical testing ranges. A pressure like 75 psi would usually be too low to fully test the valve seats, potentially masking problems. A pressure of 250 psi is outside the normal test range and could stress components or yield non-representative results. So, 150 psi is the appropriate test pressure for forward flow in this scenario.