What is the minimum acceptable incoming pressure to avoid reducing pressure below standard practice?

• A. 18 psi
• B. 20 psi
• C. 22 psi
• D. 25 psi

Answer: (B)

Maintaining a sufficient intake pressure is essential so the pump can deliver the required discharge pressures as you account for hose friction, elevation, and valve openings. Twenty pounds per square inch on the pump’s intake provides just enough cushion to keep the downstream pressure from slipping below standard practice when you open lines and operate appliances. If the incoming pressure drops to eighteen psi, there isn’t enough margin for those losses, and the pump may not maintain the intended discharge pressure. Higher values, like twenty-two or twenty-five psi, would also meet the need, but they aren’t the minimum—the question asks for the smallest acceptable pressure that still keeps system pressures in the acceptable range.