24
15.720017-V6.0
DMX model 226 en
6.5
Possible Failures
Failure
Cause
Correction
Not connected to mains
Connect the mains line
Wrong mains voltage Replace the dosing pump
Electrical failure
Return the dosing pump to the works for repair
The empty indication has responded. The
empty indication symbol blinks in the display
Remove the cause
The diaphragm breakage indication has
responded. ERROR and MBS are blinking in
the display.
Replace the diaphragm.
Leaky suction line
Exchange or seal the suction line
Cross-section of the suction line too narrow or
or suction line too long
Check with specification of Grundfos
Clogged suction line
Rinse or replace the suction line
Foot valve covered by sediment
Suspend the suction line at a higher position
Buckled suction line
Lay the suction line correctly, check for
damage
Crystalline deposits in the valves
Clean the valves
Diaphragm broken or diaphragm tappet torn
out
Exchange the diaphragm
Air in the suction line and dosing head
Wait, until the pump has deaerated
Stroke adjustment set to zero
Turn the adjustment knob in the "+" direction
Medium too viscous or density too high
Check the installation
Crystalline deposits in the valves
Clean the valves
Valves not correctly assembled
Assemble the valve inside parts in the right
order and check or possibly correct the flow
direction
Injection point blocked
Check and possibly correct the flow direction,
or remove the occlusion
Inexpert installation of lines and peripheral
equipment
Check for perviousness and correct installation
Dosing head not fully deaerated
Repeat deaeration
Degassing medium
Check the installation
Valves partially soiled or incrusted
Clean the valves
Zero-point misadjusted
Adjust the zero-point to the actual back
pressure
Fluctuations of back pressure
Application of a pressure retention valve and a
pulsation damper
Fluctuations of suction height Keep the suction level constant
Siphon effect (admission pressure higher than
back pressure)
Install a pressure retention valve
Leaky or porous suction line or pressure line
Replace the suction line or pressure line
Parts in contact with media not resistant
Replace with resistant materials
Dosing diaphragm worn out (incipient tears)
Replace the diaphragm, also observe
maintenance instructions
Fluctuations of mains voltage
Decrease the back pressure of the pump
Variation of the dosing medium (density,
viscosity)
Examine the concentration, possibly employ an
agitator
Dosing output of the pump
inaccurate
Dosing pump does not suck in
Dosing pump does not run
Dosing pump does not dose