Installation; Filtration; Noise - Danfoss PAHT Operation, Installation, And Maintenance Manual

Operation guide
7.

Installation

© Danfoss | 2023.12
Installation, Operation and Maintenance Manual for PAHT 20-90 pumps
See the figure below for instructions on how to
mount the pump and connect it to an electric
motor or combustion engine.
A
A: Pump
B: Bell housing
C: Coupling
D: Motor
If alternative mounting is required, please
contact your Danfoss sales representative for
further information.
Note: Do not add any axial or radial loads to the
pump shaft.
7.1

Filtration

Proper filtration is crucial for the performance,
maintenance and warranty of your pump.
Protect your pump, and the application in which
it is installed, by always ensuring that filtration
specifications are met, and by always changing
filter cartridges according to schedule.
Since water has very low viscosity, Danfoss PAHT
pumps have been designed with very narrow
clearances in order to control internal leakage
rates and improve component performance.
To minimize wear on the pump, it is therefore
essential to filter inlet water properly.
The main filter must have a filtration efficiency of
99.98% at 10 m. We strongly recommend that
you always use precision depth filter cartridges
rated 10 m abs. β ≥ 5,000.
10
Please note that we do not recommend bag
filters or string-wound filter cartridges, which
typically have only 50% filtration efficiency. This
means that out of 100,000 particles that enter
such filters, 50,000 particles pass right through
them; compare this to precision depth filters that
are 99.98% efficient, and only allow 20 of the
same 100,000 particles to pass through.
For more information on the importance of
proper filtration, including explanation of
filtration principles, definitions, and guidance
on how to select the right filter for your pump,
please consult our Filtration information and
specifications (Danfoss document number
521B1009).
C
B

7.2 Noise

Since the pump unit is mounted on a frame, the
overall noise level can only be determined for a
complete system. To minimize vibrations and
noise throughout the system, it is therefore very
important to mount the pump unit correctly on a
frame with dampers and to use exible hoses
rather than metal pipes where possible.
The noise level is influenced by:
• Pump speed:
High rpm makes more uid/structure-
borne pulsations/vibrations than low rpm.
• Discharge pressure:
High pressures make more noise than low
pressures.
• Pump mounting:
Rigid mounting makes more noise than
exible mounting because of the structure-
borne vibrations. Be sure to use dampers
when mounting.
• Connections to pump:
Pipes connected directly to the pump make
more noise than exible hoses because of
structure-borne vibrations.
•
Variable frequency drives (VFDs):
Motors regulated by VFDs can produce
more noise if the VFD does not have the
right settings.
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