English (GB)
25
8.2 Start-up/subsequent start-up of DMH 251, 252 and
253
Fig. 26
Start-up of DMH 251, 252 and 253
1. Connect the electrical power supply.
2. Depending on the installation, start the pump, where possible,
without counter-pressure.
See installation example for easy deaeration of the dosing head
in section
3. Set the stroke-length adjustment knob (L) to 0 %.
4. Let the pump run for approx. 5 minutes.
5. Check the oil level.
– Set the stroke-length adjustment knob (L) to 40 %.
– Let the pump run for approx. 10 minutes with a stroke-length
setting of 40 %.
– Switch off the pump, check the oil level and add oil, if
necessary.
– Refit the oil-filling screw (F).
6. Deaerate the piston flange.
– Set the stroke-length adjustment knob (L) to 15 %.
– Loosen the degassing valve (E) by one turn to the left.
– Let the pump run for approx. 5 minutes.
– Re-tighten the degassing valve (E).
The pump is now ready for operation.
After start-up
Torques
8.3 Start-up/subsequent start-up of DMH 254, 255 and
257
Fig. 27
Start-up of DMH 254, 255 and 257
1. Connect the electrical power supply.
2. Depending on the installation, start the pump, where possible,
without counter-pressure.
See installation example for easy deaeration of the dosing head
in section
.
3. Set the stroke-length adjustment knob (L) to 0 %.
4. Let the pump run for approx. 5 minutes.
5. Check the oil level.
– Set the stroke-length adjustment knob (L) to 40 %.
– Let the pump run for approx. 10 minutes with a stroke-length
setting of 40 %.
– Switch off the pump, check the oil level and add oil, if
necessary.
– Refit the oil-filling screw (F).
The pump is now ready for operation.
TM
03
64
62
45
06
Pos.
Components
1q
Dosing head screws
2
Dosing head
3b
Discharge valve
E
Degassing valve
F
Oil-filling screw with dipstick
L
Stroke-length adjustment knob
1l
Cover for stroke-length adjustment knob
M
Pressure relief valve
Warning
Risk of injury caused by squirting oil!
Oil may squirt from the oil deaeration when the pump
is running. Do not completely unscrew the oil
deaeration screw.
Wear protective clothing (gloves and goggles) when
working on the dosing head, connections or lines!
Note
Rod length of oil dipstick: 27 mm.
Immersion depth to marking: approx. 5 mm.
Note
Check the oil level at least every two weeks and add
oil, if necessary.
Only use original Grundfos gear oil!
For product numbers, see "Service kit catalogue" on
www.grundfos.com
L
F
1l
2
M
M
1q
E
3b
Pump type
Version
Description
DMH 251
Single/double
1.3 l white oil
(Paraffin 55 DAB7)
DMH 252, 10 bar
Single/double
1.3 l white oil
(Paraffin 55 DAB7)
DMH 252, 16 bar
Single/double
1.3 l DHG 68
DMH 253
Single/double
1.3 l DHG 68
Caution
After initial start-up and after each time the
diaphragm is changed, tighten the dosing head
screws.
After approximately 6-10 operating hours or two
days, cross-tighten the dosing head screws using a
torque wrench.
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
T
M
03
64
63
45
06
Pos.
Components
1q
Dosing head screws
2
Dosing head
3b
Discharge valve
F
Oil-filling screw with dipstick
L
Stroke-length adjustment knob
1l
Cover for stroke-length adjustment knob
M
Pressure relief valve
L
F
1l
2
M
M
1q
3b
