System Design; Open-Ended Systems With Direct Water Supply - Danfoss APP 13 Installation, Operation And Maintenance Manual

Operating guide
Instruction
2.

System design

© Danfoss | 2023.03
Installation, Operation and Maintenance APP 11-13
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 direct from a
feed pump.
In order to eliminate the risk of cavitation, a
positive inlet pressure of at least 2 barg (29 psig)
is always to be maintained, but it must not
exceed 5 barg (72.5 psig) continuously.
1. Place the filter (1) in the water supply line in
front of the pump.
2. Place a monitoring pressure switch (3)
between filter and pump inlet - set at min.
2 barg (29 psig) inlet pressure. The monitor-
ing pressure switch must stop the pump at
pressures lower than 2 barg
(29 psi g) inlet pressure.
3. Install a low pressure safety valve or a low
pressure relief valve (4) in order to avoid
system or pump damage in case the pump
stops momentarily (high-pressure peaks) or
starts spinning backwards.
Note: If a non return valve (2) 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.
1
2
Inlet
180R9264 | AQ115586503043en-000903 | 35
3
PS
4
Outlet