English (GB)
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7.5 Connecting the power supply cable
• Do not switch on the power supply until you are ready to start
the pump.
7.5.1 Versions with mains plug
• Insert the mains plug in the mains socket.
7.5.2 Versions without mains plug
• Connect the motor to the power supply in accordance with
local electrical installation regulations and the connection
chart on the terminal box cover.
8. Start-up/shutdown
8.1 Initial start-up/subsequent start-up
8.1.1 Checks before start-up
• Check that the rated voltage stated on the pump nameplate
corresponds to the local conditions!
• Check that all connections are secure and tighten, if
necessary.
• Check that the dosing head screws are tightened with the
specified torque and tighten, if necessary.
• Check that all electrical connections are correct.
• Cross-tighten the dosing head screws using a torque wrench.
Torques
8.1.2 Oil filling
1. Slacken and remove the oil-filling screw (F).
2. Slowly add the hydraulic oil supplied with the pump through
the oil-filling opening (F) until the oil reaches the mark on the
oil dipstick.
3. Set the stroke-length adjustment knob (L) to "0".
8.1.3 Filling the dosing head for the initial start-up for
systems without flooded suction
As assisting suction for systems without flooded suction, you can
fill the dosing head with dosing medium before the initial start-up:
1. Unscrew the discharge valve (3b).
2. Add the dosing medium to the dosing head (2).
3. Screw the discharge valve (3b) back in.
Warning
Disconnect the power supply before connecting the
power supply cable!
Before connecting the power supply cable, check
that the rated voltage stated on the pump nameplate
corresponds to the local conditions!
Do not make any changes to the power supply cable
or plug!
Caution
The assignment between the plug-and-socket
connection and the pump must be labelled clearly
(e.g. by labelling the socket outlet).
Caution
The pump can be automatically started by
connecting the power supply!
Warning
The pump must be connected to an external clearly
labelled mains switch with a minimum contact gap of
3 mm in all poles.
Warning
The specified enclosure class can only be ensured if
the power supply cable is connected with the same
degree of protection.
Caution
Observe the direction of rotation!
To protect the motor, install a motor protecting switch
or motor contactor, and set the bimetal relay to the
rated motor current for the available voltage and
frequency.
Warning
When dosing dangerous media, observe the
corresponding safety precautions!
Wear protective clothing (gloves and goggles) when
working on the dosing head, connections or lines!
Before removing the dosing head, valves and lines,
empty any remaining medium in the dosing head into
a drip tray by carefully unscrewing the suction valve.
The pump housing must only be opened by
personnel authorised by Grundfos!
Repairs must only be carried out by authorised and
qualified personnel!
Caution
Observe the flow direction of valves (indicated by an
arrow on the valve)!
Only tighten plastic valves by hand.
Pump type
Torque
[Nm]
DMH 251, 10 bar
8-10
DMH 251, 16 bar
10-12
DMH 251, 25 bar
13-15
DMH 252
8-10
DMH 253
10-12
DMH 254
50-54
DMH 255
50-54
DMH 257
50-54
Note
The pump is factory-checked, and the oil is drained
for shipping purposes. Before start-up, add the
special oil supplied with the pump.
The piston flange is filled with oil for easy start-up.
The stroke-length adjustment knob must only be
adjusted if the gear oil has been added, otherwise
the oil will leak from the piston flange.
Warning
When dosing dangerous media, observe the
corresponding safety precautions!
Wear protective clothing (gloves and goggles) when
working on the dosing head, connections or lines!
Note
Observe the flow direction of the discharge valve
(indicated by an arrow on the valve)!
