Installation Tips - Grundfos DMH 25 Série Notice D'installation Et De Fonctionnement

6.6 Installation tips

• For easy deaeration of the dosing head, install a ball valve
(11i) with bypass line (back to the dosing tank) immediately
after the discharge valve.
• In the case of long discharge lines, install a non-return valve
(12i) in the discharge line.
11i
Fig. 11 Installation with ball valve and non-return valve
• When installing the suction line, observe the following:
– Keep the suction line as short as possible. Prevent it from
becoming tangled.
– If necessary, use swept bends instead of elbows.
– Always route the suction line up towards the suction valve.
– Avoid loops which may cause air bubbles.
Fig. 12 Installation of suction line
• For non-degassing media with a viscosity similar to water, the
pump can be mounted on the tank (observe the maximum
suction lift).
• Flooded suction preferred.
• For media with a tendency to sedimentation, install the suction
line with filter (13i) so that the suction valve remains a few
millimetres above the possible level of sedimentation.
6i
13i
Fig. 13 Tank installation
• Note for suction-side installation: Depending on the dosing
flow and the line length, it may be necessary to install a
properly sized pulsation damper (4i) immediately before the
pump suction valve.
Observe section 6.4 Approximate values when using
pulsation dampers
Note
system-specific calculation from our calculation
program.
12i
p
10i
and, if necessary, request a
4i
Fig. 14 Installation with suction-side pulsation damper
• Note for discharge-side installation: Depending on the dosing
flow and the line length, it may be necessary to install a
properly sized pulsation damper (4i) on the discharge side.
To protect the system, use pulsation dampers (8i) for
Note rigid piping longer than 2 metres and tubing longer
than 3 metres, depending on pump type and size.
Fig. 15 Installation with discharge-side pulsation damper
Risk of damage to the system!
It is always recommended to use pulsation dampers
for large high-speed pumps!
Caution
Since the pulsation is influenced by many factors, a
system-specific calculation is essential. Request a
calculation from our calculation program.
• For degassing and viscous media: flooded suction.
• Install a filter in the suction line to prevent the valves from
becoming choked.
• To protect the dosing pump and the discharge line against
excessive pressure build-up, install a relief valve (6i) in the
discharge line.
6i
Fig. 16 Installation with relief valve
8i
p
10i
23