Installation Tips - Grundfos DMH 25X Installation And Operating Instructions Manual

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.
12i
11i
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.
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.
p
10i
6i
13i
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.
26
Observe section Approximate values when using pulsa-
tion dampers and, if necessary, request a system-specific
Note
calculation from our calculation program.
4i
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 rigid
piping longer than 2 metres and tubing longer than 3 me-
Note
tres, depending on pump type and size.
8i
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 sys-
tem-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.
p
6i
10i
Installation with relief valve
With open outflow of the dosing medium or a counter-pressure
below 2 bar
• Install a pressure-loading valve (7i) immediately before the
outlet or the injection unit.