Which factors are used to determine the pump's operating pressure?

• A. PDP, nozzle pressure, and friction losses.
• B. Aesthetic hose color and length.
• C. Ambient temperature only.
• D. Driver's experience.

Answer: (A)

The main idea is that pump pressure must be set to deliver the right pressure at the nozzle after losses along the hose. The nozzle pressure is the target pressure you want at the nozzle to achieve the desired stream. As water travels through hose and fittings, friction losses steal pressure; the longer and smaller the hose and the higher the flow, the greater those losses. PDP, or pump discharge pressure, is the actual pressure you set on the pump to overcome those friction losses and still deliver the nozzle pressure. So the combination of PDP, the nozzle pressure, and the friction losses along the hose path determines the pump’s operating pressure.

The other options don’t fit because aesthetic color is irrelevant to hydraulics, ambient temperature alone doesn’t set pump pressure, and driver’s experience doesn’t provide the actual hydraulic calculations needed to establish the required pressure.