22
15. Fault finding chart
Fault
Cause Remedy
1. Dosing pump does not
run.
a) Not connected to the power supply.
Connect the power supply cable.
b) Incorrect supply voltage.
Replace the dosing pump.
c) Electrical failure.
Return the pump for repair.
d) The empty indication has responded.
Remove the cause.
e) The diaphragm leakage detection has responded.
Replace the diaphragm.
2. Dosing pump does not
suck in.
a) Leaking suction line.
Replace or seal the suction line.
b) Cross-section of the suction line too small or
suction line too long.
Check with Grundfos Alldos specification.
c) Clogged suction line.
Rinse or replace the suction line.
d) Foot valve covered by sediment.
Suspend the suction line from a higher position.
e) Buckled suction line.
Install the suction line correctly. Check for
damage.
f)
Crystalline deposits in the valves.
Clean the valves.
g) Diaphragm broken or diaphragm tappet torn out.
Replace the diaphragm.
3. Dosing pump does not
dose.
a) Air in the suction line and dosing head.
Wait, until the pump has deaerated.
b) Stroke-length adjustment knob set to zero.
Turn the adjustment knob in the "+" direction.
c) Viscosity or density of medium too high.
Check the installation.
d) Crystalline deposits in the valves.
Clean the valves.
e) Valves not correctly assembled.
Assemble the inner valve parts in the right order
and check and possibly correct the flow
direction.
f)
Injection point blocked.
Check and possibly correct the flow direction
(injection unit), or remove the obstruction.
g) Incorrect installation of lines and peripheral
equipment.
Check the lines for free passage and correct
installation.
4. Dosing flow of the pump
is inaccurate.
a) Dosing head not fully deaerated.
Repeat the deareation.
b) Degassing medium.
Check the installation.
c) Parts of the valves covered in dirt or incrusted.
Clean the valves.
d) Zero point misadjusted.
Adjust the zero point to the actual counter-
pressure.
e) Counter-pressure fluctuations.
Install a pressure-loading valve and a pulsation
damper.
f)
Suction height fluctuations.
Keep the suction level constant.
g) Siphon effect (inlet pressure higher than counter-
pressure).
Install a pressure-loading valve.
h) Leaking or porous suction line or discharge line.
Replace the suction line or discharge line.
i)
Parts in contact with the medium are not resistant
to it.
Replace with resistant materials.
j)
Dosing diaphragm worn (incipient tears).
Replace the diaphragm. Also observe the
maintenance instructions.
k) Supply voltage fluctuations.
Decrease the counter-pressure of the pump.
l)
Variation of the dosing medium (density,
viscosity).
Check the concentration. Use an agitator,
if necessary.
Caution
For further error signals for the control unit, refer to the relevant section.
Summary of Contents for DMX 115-3
Page 1: ...DMX 221 GRUNDFOS ALLDOS INSTRUCTIONS Installation and operating instructions ...
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