Electric Servomotor (Optional); Electronic Preselection Counter (Optional); Electrically Heated Dosing Head (Optional); Maintenance - Grundfos DMH 28X Instrucciones De Instalación Y Operación

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.

10. Maintenance

10.1 General notes

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!
The pump housing must only be opened by
personnel authorised by Grundfos!
Repairs must only be carried out by authorised and
qualified personnel!
Switch off the pump and disconnect it from the power
supply before carrying out maintenance work and
repairs!
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.
Observe the flow direction of valves (indicated by an
Caution
arrow on the valve)!
10.2 Diaphragm leakage control for diaphragm
leakage detection
If a diaphragm leakage has been detected, first of all check
whether an error has been displayed, as different external factors
such as the heating of dosing or hydraulic medium can cause the
cracked medium between the diaphragms to be displaced into the
valve, thereby causing an error to occur.
Checks after a diaphragm leakage detection:
1. Briefly open the deaeration screw (2u) and then close it again.
2. Switch on the pump.
3. If, after a short period of time, a diaphragm leakage is
detected again, a diaphragm has broken.
After a diaphragm breakage, replace the diaphragms
and clean the non-return valve, see section
Caution
10.7 Replacing the diaphragm for dosing head with
double diaphragm .
S
U
T
1u
Fig. 33 DMH 280: dosing head with double diaphragm
Fig. 34 DMH 281-288: dosing head with double diaphragm
Pos.
I
S
T
U
1u
2u
V

10.3 Cleaning and maintenance intervals

Checking the oil level
• Check the oil level every two weeks and add oil, if necessary.
Cleaning the valves
• At least every 12 months or after 4,000 operating hours.
• If the pump does not perform.
• In the event of a fault.
Clean the valves and replace, if necessary (for stainless-steel
valves: inner valve parts).
Changing diaphragms and gear oil
• At least every 12 months or after 8,000 operating hours,
change the dosing diaphragm and gear oil.
• In dusty installation sites, change the gear oil every 3,000
operating hours.
Cleaning the ball non-return valve of the double diaphragm
• After a diaphragm breakage, remove the ball non-return valve
immediately and clean it.
Note
Replacing the grooved ring
• In the event of a fault, e.g. pump not performing, the grooved
ring can be checked by authorised personnel and replaced, if
necessary.
2u
I
S
U
T
V
1u
Components
Connection for deaeration line
Contact pressure gauge
Ball non-return valve
Connection piece
Filling screw
Deaeration screw
Deaeration screw
Only clean the ball non-return valve after a
diaphragm breakage!
2u
29