According to NFPA 20, a suction pressure regulating valve is installed according to manufacturer's recommendations and in the piping between the _______

• A. Back flow preventer and pump
• B. Discharge valve and pump
• C. Inlet and discharge
• D. Tank and pump

Answer: (A)

Suction pressure regulation is used to keep the water entering the pump at a stable, safe pressure to prevent cavitation and ensure adequate net positive suction head. Placing the suction pressure regulating valve on the suction line directly in the path to the pump ensures the pump always sees a controlled pressure, regardless of supply fluctuations. Positioning it between the backflow preventer and the pump places the regulator in the pump’s suction path after the backflow device, so the regulator protects the pump while also keeping impurities and backflow protections separate from the regulation function. The other locations don’t place the regulator on the suction side in the correct location to influence the pump’s suction effectively, so they don’t satisfy NFPA 20’s intent.