Operation; Switching On/Off; Setting The Dosing Capacity; Deaeration - Grundfos DMH 28 Serie Montage- Und Betriebsanleitung

9. Operation

9.1 Switching on/off

Before switching on the pump, check that it is
Caution
installed correctly. See sections
8. Start-up/shutdown
• To start the pump, switch on the power supply.
• To stop the pump, switch off the power supply.

9.2 Setting the dosing capacity

Fig. 32 Setting the dosing capacity
Pos. Components
L Stroke-length adjustment knob
1l Cover
2l Locking screw
3l Screw
4l Scale ring
9.2.1 Setting the dosing flow and locking the stroke-length
adjustment knob
1. Remove the cover (1l) from the stroke-length adjustment knob
(L).
2. Use a screwdriver to loosen the locking screw (2l) by
approximately 2 turns.
3. Increase or reduce the dosing flow while the pump is running.
– Slowly turn the stroke-length adjustment knob to the left or
right to set the desired dosing volume.
4. Depending on the application, tighten the locking screw (2l) so
that the stroke-length adjustment knob can still be
turned/cannot be turned any more.
5. Replace the cover (1l).
The pump cannot be operated if the stroke-length
adjustment knob is fully open! Depending on the
pump adjustment, this value may already be lower
than 100 % on the scale for system pressures higher
Caution
than 100 bar.
Open the stroke-length adjustment knob completely
and then close by approx. 10 % in order to set the
dosing flow to 100 %.

9.3 Deaeration

Manual deaeration of the dosing head (while the pump is
running)
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!
30
6. Installation and
.
3l 2l 1l
3l
L
4l
Warning
Risk of injuries caused by the dosing medium.
Dosing medium leaks from the hose nipple (I) of the
deaeration line. If the pressure is high, the medium
may squirt out. Turn the hose nipple (I) in the right
direction, or drain the dosing medium through a
suitable hose.
I
J
Fig. 33 DMH 280
Fig. 34 DMH 281-288
Pos. Components
I Hose nipple
J Deaeration hose
V Deaeration screw
DMH 280: If the deaeration screw is too loose, the
Note
O-ring can be washed away.
1. Loosen the deaeration screw (V):
– DMH 280: by max. 1/2 turn to the left.
– DMH 281-288: by 1 turn to the left.
2. Let the pump run until the dosing medium flows from the
deaeration hose (J) or hose nipple (I) without any bubbles
back into the tank.
3. Carefully tighten the deaeration screw (V).

9.4 Using the AR control unit (optional)

When using the AR control unit, observe the installation and
operating instructions for the "AR control unit" in addition to the
instructions in this manual.

9.5 Electric servomotor (optional)

To operate the servomotor, see the installation and operating
instructions for the servomotor.

9.6 Electronic preselection counter (optional)

To operate the preselection counter, see the installation and
operating instructions for the counter.

9.7 Electrically heated dosing head (optional)

To operate the temperature controller, see the installation and
operating instructions for the temperature controller.
V
V
I
J