
Troubleshooting
Type of fault
36
Stepper motor-driven diaphragm dosing pump NXP-M and NXP-P
Operating instructions
13 Troubleshooting
See below for information about how to rectify faults on the device or the
system. If you cannot eliminate the fault, please consult with the
manufacturer on further measures or return the dosing pump for repair.
13.1 Type of fault
13.1.1 Alarm LED illuminates (NXP-M)
Possible cause
Remedy
System backpressure too
high (measured at discharge
connection of dosing pump).
è
Clean blocked injection nozzle.
è
Install pulsation dampeners to
reduce pressure peaks if pipes
are too long.
è
Check function of safety valves.
Driving belt torn.
è
Contact the manufacturer.
Table 29: Type of fault: Alarm LED illuminates (NXP-M)
13.1.2 Dosing pump not delivering or output too low
Possible cause
Remedy
Wrong type of dosing pump
selected.
è
Check the dosing pump's
technical data and if necessary
select a type with a higher
delivery capacity.
Valve leaking or blocked.
è
Clean the valve and vent the
dosing pump.
è
Tighten the screw connections.
Valve installed incorrectly.
è
Reassemble the valve. Ensure
that the valve balls are located
above the valve seats.
Valve damaged (e.g. valve
balls).
è
Remove the damaged parts or
install a new valve.
Suction line is leaking.
è
Seal the leak locations or replace
the parts.
Suction line is blocked (e.g.
screen in foot valve).
è
Clean the suction line.
Shut-off valves closed.
è
Open the shut-off valves. Inspect
the dosing pump for possible
damage.
Suction head too high.
è
Set the dosing pump to feed or
reduce the suction head.
è
Install a priming aid.
Table 30: Type of fault: Dosing pump not delivering or output too low
Possible cause
Remedy
Viscosity too high.
è
Possibly reduce the concentration
of the dosing medium or increase
the temperature.
è
Install spring-loaded valves.
è
Increase the pipe diameter.
Current supply interrupted.
è
Reconnect the current supply.
The dosing pump's electrical
data does not match that of
the mains supply.
è
Check the electrical installation.
System backpressure too
high (measured at discharge
connection of dosing pump).
è
Clean blocked injection nozzle.
è
Install pulsation dampeners to
reduce pressure peaks if pipes
are too long.
è
Check function of safety valves.
Table 30: Type of fault: Dosing pump not delivering or output too low
13.1.3 Dosing pump does not prime
Possible cause
Remedy
Valve leaking or blocked.
è
Clean the valve and vent the
dosing pump.
è
Tighten the screw connections.
Valve installed incorrectly.
è
Reassemble the valve. Ensure
that the valve balls are located
above the valve seats.
Valve damaged (e.g. valve
balls).
è
Remove the damaged parts or
install a new valve.
Suction line is leaking.
è
Seal the leak locations or replace
the parts.
Suction line is blocked (e.g.
screen in foot valve).
è
Clean the suction line.
Shut-off valves closed.
è
Open the shut-off valves. Inspect
the dosing pump for possible
damage.
Suction head too high.
è
Set the dosing pump to feed or
reduce the suction head.
è
Install a priming aid.
Table 31: Type of fault: Dosing pump does not prime