NFPA 20 Fire Pump Certification Practice Exam

In NFPA 20, keeping the suction piping on a fire pump short and straight, properly sized, and free of air leaks and air pockets directly supports reliable priming and adequate suction pressure. A short, straight line minimizes friction losses and velocity head, making it easier for the pump to pull water without dropping below the vapor pressure. Adequate sizing prevents excessive velocity and pressure drop, helping maintain sufficient Net Positive Suction Head (NPSH) for the pump and reducing the chance of cavitation. Air leaks allow air to enter the suction line, which can break the water column and cause loss of prime, while air pockets—especially at high points or near fittings—can trap air and disrupt continuous primed flow. Elbows and bends, when excessive, increase head loss and promote air entrainment, worsening suction performance. Placing suction piping after the discharge check valve would isolate the suction from the pump, preventing proper priming and suction supply. For these reasons, the best practice is a short, straight, adequately sized suction line free of air leaks and air pockets.