Models 85622, 85628, 85626, 85637 Non-Metallic-REV1007 Page 7
• Pump will not cycle.
• Pump cycles, but produces no flow.
• Pump cycles, but flow rate is
unsatisfactory.
• Pump cycle seems unbalanced.
• Pump cycle seems to produce
excessive vibration.
Excessive suction lift
in system.
For lifts exceeding
20 feet (6 meters), filling the pumping
chambers with liquid will prime the
pump in most cases.
Excessive flooded
suction in system.
For flooded
conditions exceeding 10 feet (3
meters) of liquid, install a back pressure
device.
System head exceeds
air supply pressure.
Increase the
inlet air pressure to the pump. Most
diaphragm pumps are designed for 1:1
pressure ratio at zero flow.
Air supply pressure or
volume exceeds system head.
Decrease inlet
air pressure and volume to the pump
as ca lculate d on th e publish ed
PERFORMANCE CURVE. Pump is
cavitating the fluid by fast cycling.
Undersized suction
line.
Meet or exceed
pump connection recommendations
s ho wn on th e D IM E NS I ONA L
DRAWING.
Res tricte d or
undersized air line.
Install a larger
air line and connection. Refer to air
inlet recommendations shown in your
pump’s SERVICE MANUAL.
Check the externally
serviceable air distribution system of
the pump.
Disassemble and
inspect the main air distribution valve,
pilot valve and pilot valve actuators.
Refer to the parts drawing and air valve
section of the SERVICE MANUAL.
Check for clogged discharge or closed
valve before reassembly.
Rigid pipe connections
to pump.
Install flexible
connectors and a surge suppressor.
Blocked air exhaust
muffler.
Remove muffler
screen, clean or de-ice and reinstall.
Refer to the Air Exhaust section of your
pump SERVICE MANUAL.
Pumped fluid in air
exhaust muffler.
Disassemble
pump chambers. Inspect for diaphragm
rupture or loose diaphragm plate
assembly. Refer to the Diaphragm
Replacement section of your pump
SERVICE MANUAL.
Suction side air
leakage or air in product.
Visually inspect
all suction side gaskets and pipe
connections.
Obstructed check
valve.
Disassemble the wet
end of the pump and manually dislodge
obstruction in the check valve pocket.
Refer to the Check Valve section of
the pump SERVICE MANUAL for
disassembly instructions.
Worn or misaligned
check valve or check valve seat.
Inspect check
valves and seats for wear and proper
seating. Replace if necessary. Refer
to Check Valve section of the pump
SERVICE MANUAL for disassembly
instructions.
Blocked suction line.
Remove or flush
obstruction. Check and clear all suction
screens and strainers.
Blocked discharge
line.
C he ck fo r
obstruction or closed discharge line
valves.
Blocked pumping
chamber.
Disassemble and
inspect the wetted chambers of the
pump. Remove or flush any obstructions.
Refer to the pump SERVICE MANUAL
for disassembly instructions.
Entrained air or
vapor lock in one or both pumping
chambers.
Purge chambers
through tapped chamber vent plugs.
PURGING THE CHAMBERS OF AIR
CAN BE DANGEROUS! Any model
with top-ported discharge will reduce or
eliminate problems with entrained air.
If your pump continues to perform
below your expectations, contact your
technical services group for a service
evaluation.
To order call 1-800-548-1191 or visit www.partdeal.com - info@partdeal.com
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