Which term describes the pressure remaining in a water supply system while water is flowing?

Which term describes the pressure remaining in a water supply system while water is flowing?

• A. Static
• B. Flow
• C. Residual
• D. Dynamic

Answer: (C)

The pressure remaining in a water supply system while water is flowing is called residual pressure. This term distinguishes what happens when water is moving from static pressure, which is the pressure present when no water is flowing. As water flows, friction, fittings, and elevation losses reduce pressure, and the residual pressure is what stays at a given flow rate. While some may loosely refer to pressure during flow as dynamic pressure, the standard term used in fire protection is residual pressure, because it specifically describes the pressure that remains during flow. If the system can’t maintain a minimum residual pressure at required flow, adjustments to pumps, mains, or valves are needed.

The pressure remaining in a water supply system while water is flowing is called residual pressure. This term distinguishes what happens when water is moving from static pressure, which is the pressure present when no water is flowing. As water flows, friction, fittings, and elevation losses reduce pressure, and the residual pressure is what stays at a given flow rate. While some may loosely refer to pressure during flow as dynamic pressure, the standard term used in fire protection is residual pressure, because it specifically describes the pressure that remains during flow. If the system can’t maintain a minimum residual pressure at required flow, adjustments to pumps, mains, or valves are needed.