That part of the total available pressure not used to overcome friction or gravity while forcing water thru pipe, fittings, adaptors, and fire hose is known as ______.

• A. Residual pressure
• B. Static pressure
• C. Flow pressure
• D. Head pressure

Answer: (A)

The main idea here is that the pump provides a total available pressure, but as water moves through hoses, fittings, adaptors, and any elevation changes, part of that pressure is consumed by friction losses and by lifting the water against gravity. What’s left after all those losses is the residual pressure—the pressure still available at the discharge to drive the flow through the nozzle. This remaining pressure is what actually determines how well the water is projected and what flow you can achieve.

Static pressure is the pressure when no water is flowing, so it’s not about losses during transit. Head pressure relates to pressure from height differences, not the portion left after friction and gravity losses. Flow pressure isn’t a standard term used to describe this concept.