Troubleshooting
Swing Piston Pumps NPK 25
16
Translation of original Operating and Installation Instructions, english, KNF 121581-121584 08/16
9. Troubleshooting
NPK 25 AC:
DANGER
Extreme danger from electrical shock!
Disconnect the pump power supply before working
on the pump.
Make sure the pump is deenergized and secure.
NPK 25 DC:
Disconnect the pump power supply before working on the
pump.
Make sure the pump is deenergized and secure.
All pumps:
Check the pump (see Tab. 11 and 12).
Pump does not transfer
Cause
Fault remedy
Thermal switch has operated
following to over-heating.
Disconnect pump from mains.
Allow pump to cool.
Trace cause of over-heating and eliminate it.
Connections or lines blocked.
Check connections and lines.
Remove blockage.
External valve is closed or filter
is clogged.
Check external valves and filters.
Condensate has collected in
pump head.
Install pump at highest point in system.
Piston seal or valve plate is
worn.
Change piston seal and valve plate (see section 8.3).
Tab. 11
The pump does not achieve the output (flow, pressure or vacuum) specified in the Technical
data or the data sheet
Cause
Fault remedy
Condensate has collected in
pump head.
Install pump at highest point in system.
There is gauge pressure on
pressure side and at the same
time vacuum or a pressure
above atmospheric pressure on
suction side.
Change the pressure conditions.
Pneumatic lines or connection
parts have an insufficient cross
section.
Disconnect pump from system to determine output values.
Eliminate throttling (e.g. valve) if necessary.
Use lines or connection parts with larger cross section if
necessary.
Leaks occur on connections,
lines or pump head.
Eliminate leaks.
Connections or lines completely
or partially jammed.
Check connections and lines.
Remove the jamming parts and particles.
