Maintenance; General Notes; Cleaning And Maintenance Intervals; Cleaning The Suction And Discharge Valves - Grundfos DMX 226 Montage- Und Betriebsanleitung

11. Maintenance

11.1 General notes

Warning
When dosing dangerous media, observe the
corresponding safety precautions!
Risk of chemical burns!
Wear protective clothing (gloves and goggles) when
working on the dosing head, connections or lines!
Do not allow any chemicals to leak from the pump.
Collect and dispose of all chemicals correctly!
Warning
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!
During transport, the deaeration opening must be
closed with the screw plug!
Caution
Before start-up, replace the screw plug by the
deaeration screw!

11.2 Cleaning and maintenance intervals

In the event of a diaphragm leakage, the dosing
liquid may leak out of the hole in the intermediate
flange between the pump and the dosing head. The
parts inside the housing are protected from the
dosing liquid for a short time (depending on the type
Caution
of liquid) by the housing sealing. It is necessary to
check regularly (daily) if liquid is leaking out of the
intermediate flange. For maximum safety, we
recommend the pump version with diaphragm
leakage detection.
11.2.1 Changing the gear grease
Warning
The gear grease must only be changed by authorised
and qualified personnel.
For this purpose, send the pump to Grundfos or an
authorised service workshop.
To ensure trouble-free operation, it is recommended to have the
gear grease changed after five years or after 20,000 operating
hours.
11.2.2 Cleaning the diaphragm and valves
Clean the diaphragm and valves, and replace, if necessary
(with stainless-steel valves: inner valve parts):
• At least every 12 months or after 4,000 operating hours.
When operating with a counterpressure of 16 bar, every six
months or after 2,000 operating hours.
• In the event of a fault.

11.3 Cleaning the suction and discharge valves

If possible, rinse the dosing head,
Caution
e.g. by supplying it with water.
If the pump looses capacity, clean the suction and discharge
valves as follows:
1. Unscrew the valve.
2. Unscrew the screw part resp. valve seat with round pliers.
3. Clean all parts. Replace faulty parts by new ones.
4. Re-assemble the valve.
5. Replace the O-rings by new ones. Refit the valve.
Observe the direction arrow on the valve.
*
Fig. 28 Stainless-steel or plastic valve DN 20,
* spring-loaded as an option
The O-rings must be correctly placed in the specified
groove.
Caution
Observe the flow direction (indicated by an arrow on
the valve)!

11.4 Maintenance of the relief valve

11.4.1 Cleaning and maintenance intervals
Clean the relief valve, and replace the diaphragm, if necessary.
• At least every 12 months or after 8,000 operating hours.
• In the event of a fault.
11.4.2 Replacing the diaphragm of the relief valve
1. Switch off the pump and disconnect it from the power supply.
2. Make it impossible for a return flow or overpressure to occur.
3. Loosen the four screws on the top part of the relief valve.
4. Remove the top part of the relief valve.
5. Remove the diaphragm.
6. Insert a new diaphragm.
7. Refit the top part of the relief valve and cross-tighten the
screws.
Maximum torque: 6 Nm.
8. Start up the dosing system.
9. Tighten the screws on the top part of the relief valve after
48 operating hours.
Maximum torque: 6 Nm.
*
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