Hale PSD - Manual (Page 16)

Engine RPM Higher than Necessary for Desired Volume in Pressure
1. Restriction in Suction Hose Strainer or Impeller Vanes.
a. Inspect strainer to clear away all debris.
b. Pressure backwash will usually clear impeller vane when pump is topped.
c. Check condition of the suction hose. On an old, or defective hose, the liner may be
pulled loose when pumping, thus reducing the inside diameter of the hose itself.
2. Undersize Suction Hose.
a. When pumping at higher than normal lifts, or altitudes, use a larger suction.
3. Truck Transmission in Too Low a Gear.
a. Proper pumping gear is usually high, or direct drive. Consult apparatus instructions.
Pump Will Not Develop Sufficient Pressure
1. Often the remedies for low pump capacity will also correct low pressure.
2. Pump RPM too Low
a. Use a tachometer to check engine speed.
3. Pump Capacity Limits Pump Pressure.
a. Do not attempt to pump a greater volume of water at a given pressure than the pump
was designed to handle. Cavitation will result. Pump efficiency will be seriously impaired.
(NOTE: Prolonged pumping while pump is cavitating will damage impeller.)
b. Reduce volume by restricting discharge until the desired pressure is obtained.
Volume and Pressure
Capacity at 150 PSI
70% Capacity at 200 PSI
50% Capacity at 250 PSI