Fault Finding Chart - Grundfos DMX 227 Montage- Und Betriebsanleitung

11. Fault finding chart

Fault
1. Dosing pump does not
run.
2. Dosing pump does not
suck in.
3. Dosing pump does not
dose.
4. Dosing flow of the pump
is inaccurate.
Cause
a) Not connected to the power supply.
b) Incorrect supply voltage.
c) Electrical failure.
d) The diaphragm leakage detection has responded.
a) Leaking suction line.
b) Cross-section of the suction line too small or
suction line too long.
c) Clogged suction line.
d) Foot valve covered by sediment.
e) Crystalline deposits in the valves.
f) Diaphragm broken or diaphragm tappet torn out.
g) Dosing tank is empty.
a) Air in the suction line and dosing head.
b) Viscosity or density of medium too high.
c) Crystalline deposits in the valves.
d) Valves not correctly assembled.
e) Injection point blocked.
f) Incorrect installation of lines and peripheral
equipment.
a) Dosing head not fully deaerated.
b) Degassing medium.
c) Parts of the valves covered in dirt or incrusted.
d) Counterpressure fluctuations.
e) Suction height fluctuations.
f) Siphon effect (inlet pressure higher than
counterpressure).
g) Leaking or porous suction line or discharge line.
h) Parts in contact with the medium are not resistant
to it.
i) Dosing diaphragm worn (incipient tears).
j) Variation of the dosing medium (density,
viscosity).
Remedy
Connect the power supply cable.
Replace the dosing pump.
Return the pump for repair.
Replace the diaphragm.
Replace or seal the suction line.
Check with Grundfos specification.
Rinse or replace the suction line.
Suspend the suction line from a higher position.
Clean the valves.
Replace the diaphragm.
Change the tank.
Wait until the pump has deaerated.
Check the installation.
Clean the valves.
Assemble the inner valve parts in the right order
and check and possibly correct the flow
direction.
Check and possibly correct the flow direction
(injection unit), or remove the obstruction.
Check the lines for free passage and correct
installation.
Repeat the deareation.
Check the installation.
Clean the valves.
Install a pressure-loading valve and a pulsation
damper.
Keep the suction level constant.
Install a pressure-loading valve.
Replace the suction line or discharge line.
Replace with resistant materials.
Replace the diaphragm. Also observe the
maintenance instructions.
Check the concentration. Use an agitator, if
necessary.
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