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9.3 General faults
10. Disposal
This product or parts of it must be disposed of in an
environmentally sound way. Use appropriate waste
collection services. If this is not possible, contact the
nearest Grundfos company or service workshop.
See also end-of-life information at
www.grundfos.com/product-recycling.
Fault
Possible cause
Possible remedy
Dosing flow too high
Inlet pressure greater than
backpressure
Install additional spring-loaded valve (approx. 2
bar) on the outlet side. Check settings.
Increase pressure differential.
No dosing flow or
dosing flow too low
Air in dosing head
Deaerate the pump.
Faulty diaphragm
Change the diaphragm. See section
Leakage/fracture in lines
Check and repair lines.
Valves leaking or blocked
Check and clean valves.
Valves installed incorrectly
Check that the arrow on the valve housing is
pointing in the direction of flow. Check whether all
O-rings are installed correctly.
Blocked inlet line
Clean inlet line/install strainer.
Suction lift too high
Reduce suction lift.
Install priming aid.
Viscosity too high
Use lines with larger diameter.
Install spring-loaded inlet and outlet valve.
Deaeration valve open
Close the deaeration valve.
Irregular dosing
Valves leaking or blocked
Tighten up valves, replace valves if necessary.
See section
Backpressure fluctuations
Keep backpressure constant.
Liquid escaping from
the drain opening on
the dosing head
Faulty diaphragm
Immediately separate the pump from the power
supply!
Observe section
and especially section
Liquid escaping
Dosing head screws not
tightened
Tighten up screws. See section
Valves not tightened
Tighten up valves/union nuts. See section
Pump not sucking in
Suction lift too high
Reduce suction lift; if necessary, provide positive
inlet pressure.
Backpressure too high
Open the deaeration valve.
Soiled valves
Flush system, replace valves if necessary. See
section
