The Dosing Flow Is Inaccurate; Permanent Leakage From The Integral Relief Valve; The Diaphragm Leakage Sensor Does Not Operate Properly - Grundfos DMX 221 Instrucciones De Instalación Y Funcionamiento

8.4 The dosing flow is inaccurate

Cause
There is gas in the dosing head.
There are crystalline deposits in the valves.
The zero point is set incorrectly.
The counterpressure is fluctuating.
The pressure in the inlet line is fluctuating.
The inlet or outlet line is too small or too long.
There is siphon effect.
The inlet line or outlet line is leaking or porous.
Parts in contact with the dosing medium are not
resistant to it.
The dosing diaphragm is worn (incipient rips).
The dosing pump is used at the high end of its
performance range in an installation with fluctuat-
ing supply voltage.
The density or the viscosity of the dosing medium
varies.

8.5 Permanent leakage from the integral relief valve

Cause
The outlet valve or the outlet line is blocked.
The opening pressure of the integral relief valve is
set too low.
The diaphragm of the integral relief valve is defec-
tive.
The ball or seat of the integral relief valve is defec-
tive.
The integral relief valve is dirty.

8.6 The diaphragm leakage sensor does not operate properly

Cause
Malfunction in the sensor.
The AR control unit or the electronic unit for
optical sensor does not operate properly.
Remedy
Deaerate the dosing head.
Clean the valves.
Adjust the zero point to match the actual
counterpressure.
Install a pressure-loading valve and a pulsa-
tion damper.
Keep a constant level in the dosing tank by
installing a break tank.
Install a pulsation damper.
Install a pulsation damper.
Install a pressure-loading valve.
Check and replace the inlet line or outlet line.
Replace with parts made of a resistant mate-
rial.
Replace the dosing diaphragm.
Lower the counterpressure of the pump.
Make sure the density or the viscosity of the
dosing medium does not vary. Use a stirrer.
Remedy
Clean the outlet valve and the outlet line.
Set the opening pressure of the integral
relief valve correctly.
Replace the diaphragm of the integral re-
lief valve.
Replace the defective parts.
Clean the integral relief valve.
Remedy
Clean the sensor. If the sensor is not working af-
ter cleaning, replace it with new one.
Contact Grundfos for service.
DMX 221 | | 36