System Design; Open-Ended Systems With Direct Water Supply; Preferred System Design And P&Id - Danfoss APP W HC Series Operation Manual

Instruction | APP W HC 15 - 30 pumps
2.

System design

Media filter
PI
Feed
The design of the system must ensure that
self-emptying of the pump during standstill is
avoided .
The inlet pressure of the pump must never
exceed the outlet pressure . This may typically
occur in boosted or open-ended systems with
direct water supply .
2.1 Open-ended systems with direct water
supply
The pump is supplied with water directly from a
feed pump .
The inlet pressure for APP W HC 15-30 must be at
least 2 barg (29 psig) .
To protect the pump from being damaged by
peaks of high-pressure in case the pump stops
momentarily, it is required to mount a low-
pressure relief valve on the inlet line .
2.2 Preferred system design and P&ID
1 . Dimension the inlet line to obtain mini-
mum pressure loss (large flow, minimum
pipe length, minimum number of bends/
connections, and fittings with small
pressure losses) .
2 . Place an inlet filter (1) in front of the
APP W HC pump (2) . Please consult Danfoss
filter data sheet for guidance on how to
select the right filter . Thoroughly clean
pipes and flush system prior to start-up .
3 . Place a monitoring pressure switch (3) set
at min . inlet pressure between filter and
pump inlet . The monitoring switch must
stop the pump at pressures lower than
minimum pressure .
4 . Use flexible hoses (4) to minimize vibrations
and noise .
5 . In order to eliminate the risk of damage
and cavitation, a positive pressure at the
inlet (5) is always to be maintained at min .
inlet pressure and max . inlet pressure .
9
PI PI PI
1 1
5
Fresh water
permeat flush
180R9410 | AQ282628894589en-000801 | IOM APP W HC 15-30 Pumps | 01.2022
It is recommend to install safety valve or a
pressure relief valve (9) in order to avoid
high-pressure peaks in case the pump stops
momentarilly or is spinning backwards .
6 .
7 .
8 .
Note: If a non-return valve is mounted in the
inlet line, a low-pressure relief valve is also
required between non-return valve and pump
as protection against high-pressure peaks.
3
PT
2
7
4
6
Inlet
For easy system bleeding and flushing, a
bypass non-return valve (6) is integrated in
the APP W HC pump .
A non-return valve (7) in outlet can be
installed in order to avoid backspin of the
pump . The volume of water in the mem-
brane vessel works as an accumulator and
will send flow backwards in case of the
pump stops momentarily .
A safety valve or a pressure relief valve (8)
can be installed in order to avoid system
damage as the Danfoss APP W HC pump
creates pressure and flow immediately after
start-up, regardless of any counter
pressure .
8
PI
PI
Brine
Outlet
Permeate
35