If you were pumping a pumper operating at the top of a 75-foot hill, the adjustment you must make to the PDP to account for the elevation pressure is to:

If you were pumping a pumper operating at the top of a 75-foot hill, the adjustment you must make to the PDP to account for the elevation pressure is to:

• A. Subtract 37.5 psi
• B. Add 37.5 psi
• C. Add 32.5 psi
• D. Subtract 32.5 psi

Answer: (B)

Pumping uphill requires extra pressure to overcome the elevation head—the weight of the water column rising to the higher position. When the pumper sits at the top of a 75-foot hill, you must add pressure to the PDP to ensure the nozzle ends up at the desired pressure despite the climb. In field practice this elevation head is commonly approximated as 0.5 psi per foot of elevation. So for 75 feet, you add 75 × 0.5 = 37.5 psi to the PDP. Using a more exact hydrostatic value (about 0.433 psi per foot) would give 32.5 psi, but the standard convention for this question is to add 37.5 psi. Remember, this accounts for elevation head; friction losses are handled separately.

Pumping uphill requires extra pressure to overcome the elevation head—the weight of the water column rising to the higher position. When the pumper sits at the top of a 75-foot hill, you must add pressure to the PDP to ensure the nozzle ends up at the desired pressure despite the climb. In field practice this elevation head is commonly approximated as 0.5 psi per foot of elevation. So for 75 feet, you add 75 × 0.5 = 37.5 psi to the PDP. Using a more exact hydrostatic value (about 0.433 psi per foot) would give 32.5 psi, but the standard convention for this question is to add 37.5 psi. Remember, this accounts for elevation head; friction losses are handled separately.