Grundfos DMH 25X Installation And Operating Instructions Manual page 36

Stainless-steel or plastic DN 8 valve, spring-loaded as an option
Plastic DN 20 valve
36
1)
Stainless-steel (1) or plastic (2) DN 20 valve, spring-loaded as an
option
1)
DN 32 valve, suction side (1) and discharge side (2)
The O-rings must be correctly placed in the specified
groove.
Observe the flow direction (indicated by an arrow on the
Caution
valve)!
Only tighten plastic valves by hand.
2)
2)