Preferred Ro System Design With Erd; Preferred Ro System Design With Pumps And Erds In Parallel; Reversible Pumps; Building Up The Pump Unit With Bowex Coupling - Danfoss APP Series Installation, Operation And Maintenance Manual

Operation guide
3. Building up the
pump unit with BoWex
coupling
3-5 mm
0.12-0.20 inch
46 | 180R9346 | AQ240486503020en-001702
Installation, Operation and Maintenance APP 53-92 pumps

2.3 Preferred RO system design with ERD

For P&ID of a setup with an iSave, please see the
iSave® Data sheet 521B1378
2.4 Preferred RO system design with pumps
and ERDs in parallel
For systems with Danfoss pumps and ERDs in
parallel, please see our publication 180R9354,
Guideline for Parallel-coupled pumps and ERD.

2.5 Reversible pumps

If exposed to high-pressure in the outlet while
the electric motor is not energized, the pumps
may start spinning backwards. This will not harm
the pumps as long as the pressure in the inlet
does not exceed the max. pressure peak of
10 barg(145 psig).
If a non-return valve is mounted in the inlet line,
a low-pressure relief valve is required as protec-
tion against high-pressure pulses and high-pres-
sure in general.
Alternatively a high-pressure check valve can be
mounted in the pump discharge line to prevent
the pump from reversing.
The setup of "open-end system" ensures that the
inlet pressure does not exceed 10 barg (145 psig),
when a non-
return valve is mounted in the inlet.

3.1 Assembly of the coupling

We recommend to inspect bores, shaft,
keyway and feather key for dimensional
accuracy before assembly.
Heating the hubs lightly (approx. 80 °C)
allows for an easier mounting on the
shaft.
Please pay attention to the ignition risk
in potentially explosive atmospheres!
3.2 Alignment between the motor and
pump shaft
2.6 General comments
A good filtration is vital to ensure a long and
trouble-free life of the pump.
As water has very low viscosity, the APP pumps
have been designed with very narrow clearance
in order to control internal leakage rates and
improve component performance. Therefore it is
important that the inlet water is filtered properly
to minimize the wear of the pump.
The main filter must have a filtration efficiency of
99.98% at 10 μm. We recommend to use
precision depth filter cartridges rated 10 μm abs.
β10 ≥ 5000 (equivalent to a filtration efficiency of
99.98%). Bag filters and string wounded filter
cartridges typically have only 50% filtration
efficiency. This means that for each 100,000
particles reaching the filter, 50,000 particles pass
through it compared to only 20 particles in a
filter with an efficiency of 99.98%.
For more information on the importance of
proper filtration, please see our data sheet
521B1009 on "Filtration", which also will provide
you with an explanation of filtration definitions
and a guidance on how to select the right filter.
Monitoring
It is recommended to continuously monitor the
following conditions:
• Filter clogging
• Pressure (inlet- and outlet side of the pump)
Touching the heated hubs causes
burns.
Please wear safety gloves.
With the assembly please make sure
that the spline of the hub is fully co-
vered by the internal spline of elasto-
mer (please observe mounting dimen-
sions L ). Disregarding this advice
coupling
may cause damage to the coupling.
© Danfoss | 2023.03