26850A005
4
THE PUMP MUST BE INSTALLED WITH A PRESSURE RELIEF VALVE IN DISCHARGE LINE
TROUBLESHOOTING
Pump fails to build pressure with discharge closed
Failure to hold pressure with discharge open
Pump is noisy
Pump gets hot
Pressure gauge shows abnormal fluctuation
Regulator chatter
POSSIBLE CAUSE OF PROBLEM
1. Pump not primed
X
2. Valve closed in suction line
X
X
3. Suction line or sediment chamber clogged
X X X
4. Air leak in suction line
X X X
5. Pressure regulator valve badly worn or not properly adjusted
X X
6. Pump packing or valves badly worn
X
X X
7. Pump cylinder body cracked
X X X
8. Holes in discs are too large
X
9. Need suction surge arrester
X
10. Water in crankcase
X
11. Worn connecting link bearings
X
X
12. Lack of oil in crankcase
X
X
13. Foaming mixture
X
X X
14. Regulator plunger sticking
X
15. Unloader stuffing box nut too tight
X
16. Foreign matter under pump valve
X
X X
17. Discharge surge arrester inoperative
X
X
18. Loose piston rod
X
19. Improper preload of crankshaft bearings
X
X
1. Pump priming is usually not necessary when the pump is
installed correctly. However, there are certain conditions
which may make it necessary to prime the pump to get
the pumping action started. Priming will be required
when it is impossible for the plunger to displace the
air in the pump and replace it with water. This can be
caused by a high suction lift, the valves being stuck on
the seat or by valves sticking due to extreme corrosion.
A pump will not prime readily if someone has tampered
with the valve springs causing them to exert undue
pressure of the valve plates against the valve seats.
2. A gate valve is sometimes installed in the suction line
between a tank or pressure line and the pump sediment
chamber. It will shut off the supply source in order
to clean the sediment chamber or to perform pump
repairs. If this valve is partially or fully closed, it will
interfere with the flow of water to the pump suction. This
may cause severe knocking and vibration of the pump
because the water cannot flow into the cylinder cavities
fast enough.
3. A sediment chamber should be installed in the suction
line between the gate valve and the pump suction. The
strainers in the sediment chambers are sufficient to
allow a free flow of liquid to the pump. If the strainers
become severely clogged, they will completely stop the
flow of liquid to the pump.
4. Any plunger pump operating at a high pressure will
not perform properly nor quietly if a mixture of air and
water is allowed to enter the pump suction. A small air
leak in the suction line will cause the pump to knock
and vibrate excessively by allowing the pump to draw a
certain amount of water mixed with air on each stroke of
the piston. A large air leak will cause the pump to lose
prime after which it cannot be reprimed until the air
leak is stopped. Air leaks may occur at the joints of the
suction line piping, at the gate valve in the suction line,
at the gasket sealing the cap on the sediment chamber,
by a crack in the suction wall of the cylinder body, or by
air drawing past the packing on the suction stroke if the
packing is badly worn.
Explanation of the Service Chart
