8.4 The dosing flow is inaccurate
Cause
Remedy
There is gas in the dosing head.
Deaerate the dosing head.
There are crystalline deposits in the valves.
Clean the valves.
The zero point is set incorrectly.
Adjust the zero point to match the actual
counterpressure.
The counterpressure is fluctuating.
Install a pressure-loading valve and a pulsa-
tion damper.
The pressure in the inlet line is fluctuating.
Keep a constant level in the dosing tank by
installing a break tank.
Install a pulsation damper.
The inlet or outlet line is too small or too long.
Install a pulsation damper.
There is siphon effect.
Install a pressure-loading valve.
The inlet line or outlet line is leaking or porous.
Check and replace the inlet line or outlet
line.
Parts in contact with the dosing medium are not
resistant to it.
Replace with parts made of a resistant mate-
rial.
The dosing diaphragm is worn (incipient rips).
Replace the dosing diaphragm.
The dosing pump is used at the high end of its
performance range in an installation with fluctuat-
ing supply voltage.
Lower the counterpressure of the pump.
The density or the viscosity of the dosing medium
varies.
Make sure the density or the viscosity of the
dosing medium does not vary. Use a stirrer.
8.5 Permanent leakage from the integral relief valve
Cause
Remedy
The outlet valve or the outlet line is blocked.
Clean the outlet valve and the outlet line.
The opening pressure of the integral relief valve is
set too low.
Set the opening pressure of the integral
relief valve correctly.
The diaphragm of the integral relief valve is defec-
tive.
Replace the diaphragm of the integral re-
lief valve.
The ball or seat of the integral relief valve is defec-
tive.
Replace the defective parts.
The integral relief valve is dirty.
Clean the integral relief valve.
8.6 The diaphragm leakage sensor does not operate properly
Cause
Remedy
Malfunction in the sensor.
Clean the sensor. If the sensor is not working af-
ter cleaning, replace it with new one.
The AR control unit or the electronic unit for
optical sensor does not operate properly.
Contact Grundfos for service.
DMX 221 | |
39