Hale PSD - Manual (Page 14)

Many Centrifugal Pump Troubles are Due to Air Leaks
Procedure to follow to detect possible air leaks:
A. Start engine with pump disengaged and with pump drained.
B. Tightly close pump drain valve as well as booster tank suction and discharge valves (if
connected to a booster tank). Tighten caps on suction and discharge openings. Then pull
out primer handle.
C. Observe hand on vacuum gauge until it reaches a stationary position; this should be 20
inches or over.
D. Release primer handle and carefully watch vacuum gauge hand. If hand drops back rapidly,
it indicates a leak, which must be located and corrected. If it stands stationary, or moves
back very slowly, it indicates either “no leak”, or a minor leak, which will not interfere with
satisfactory operation.
E. Should test indicate a leak in pump proper, the stuffing box may need adjustment, if
equipped with packing. If the pump is equipped with a mechanical seal, it may require
service.
F. Now remove discharge cap. If vacuum gauge hand returns toward zero, more rapidly than
before cap was removed, it indicates that the self-closing poppet valve within the discharge
manifold is not properly seated and this condition should be corrected.
G. When difficulty is experienced in locating an air leak, it may be found by connecting pump
suction to a hydrant. With hydrant pressure on pump, look for water leaks, any one of
which indicates a possible air leak. When connected to a booster tank, there may be an air
leak in booster line valves - in valve proper, or around valve stem. The former may
necessitate replacement of complete valve while the latter may be corrected by replacing
valve stem.
H. Do not overlook possibility of air leaks in suction hose or couplings. To test for such leaks,
connect suction hose to pump suction, place pump suction cap over the end of the suction
hose, and test in the same manner as described above as to the motion of the vacuum
gauge hand.
I. It is a very good idea to make periodic tests for air leaks. NOTE: Excessive air leakage
may delay, or even prevent priming.