Fault Finding The Product; The Dosing Pump Does Not Run; The Dosing Pump Does Not Suck In; No Dosing Flow - Grundfos DMX 221 Instrucciones De Instalación Y Funcionamiento

8. Fault finding the product

8.1 The dosing pump does not run

Cause
The pump is not connected to the power supply.
Incorrect supply voltage.
Electrical failure in the motor or the pump control unit.
The level sensor in the supply tank has stopped the pump,
because the tank is empty.
The diaphragm leakage sensor has stopped the pump, be-
cause there is a leakage.

8.2 The dosing pump does not suck in

Cause
The inlet line is leaking.
The inlet line is too small or too long.
The inlet line is clogged.
The foot valve is covered by sediment.
The inlet line is buckled.
There are crystalline deposits in the valves. Clean the valves.
The dosing diaphragm is broken.

8.3 No dosing flow

Cause
There is air in the inlet line and the dosing
head.
The stroke-length adjusting knob is set to
zero.
The viscosity of the dosing medium is too
high.
There are crystalline deposits in the valves. Clean the valves.
The valves are not assembled correctly.
The injection point is blocked.
The lines and peripheral equipment are in-
stalled incorrectly.
Remedy
Connect the power supply cable.
Replace the dosing pump.
Return the pump for repair.
Refill the tank and start the pump.
Replace the diaphragm and start
the pump.
Remedy
Check and seal or replace the inlet line.
Check with Grundfos specifications and adapt the
inlet line to the specifications.
Clean or replace the inlet line.
Clean the foot valve.
Clean the tank from the sediment or shorten the in-
let line.
Install the inlet line correctly. Check for damage.
Replace the dosing diaphragm.
Remedy
Wait until the pump has deaerated.
Turn the stroke-length adjusting knob.
Make sure the dosing pump and the installation are
suitable for the viscosity of the dosing medium.
Assemble the valve parts in the right order. Ensure
correct flow direction.
Ensure correct flow direction (injection unit). Re-
move the obstruction.
Install the lines and peripheral equipment correctly.
Ensure free passage.
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