48 | 180R9289 | AQ109686503106en-001102
© Danfoss | 2023.01
Operation guide
Installation, Operation and Maintenance Manual for PAHT 256-308 pumps
4.
Initial start-up
3.4 Protection from too high pressures
The pump should be protected against too high
pressure by means of a safety valve or a pressure
relief valve.
The valve should be placed as close to the pump
as possible.
The opening characteristics of the valve must not
result in peak pressures higher than 100 barg
(1450 psig).
Both the inlet and outlet lines must be flexible
soft hoses.
The valve outlet must not be connected
directly to the pump suction line. It must be
connected directly to the drain.
3.5 Connections
I: Inlet
O: Outlet
C: Bleeding
D:
Parallel key
3.6 Grounding
To prevent stray current corrosion we recom-
mend grounding of the pump and all other parts
in the system. All parts in the system must be
electrical potential equalized to a single
reference point (grounding point).
It is recommended that the electrical resistance
in the grounding cable is equal to or below 0.25
Ohm towards the grounding point.
1.
Flush inlet line before connecting the
pump, to remove possible impurities from
pipes, hoses etc.
2.
Loosen top bleeding plug “C” (see item 3.5)
using an allen key (only plugs with internal
hexagan sockets). Retighten the plug, when
water appears from the bleeding plug.
3.
Make sure that the direction of rotation of
the electric motor corresponds to the direc-
tion of rotation of the pump (see label on
pump).
4.
Now the pump is ready for start-up.
WARNING:
Make sure that the direction of rotation of the
electric motor corresponds to the direction of
rotation of the pump (see label on pump).
Otherwise the pump will be damaged if a
check valve is placed between pump and feed
pump.
5. Operation
5.1 Temperature
Fluid temperature:
Min. +2°C to max. +50°C
(Min. +35.6°F to max. +122°F)
Ambient temperature:
Min. +2°C to max. +50°C
(Min. +35.6°F to max. +122°F)
Storage temperature:
Min. -40°C to max. +70°C
(Min. -40°F to max. +158°F)
In case of lower operating temperatures, please
contact the Danfoss Sales Organization.
5.2 Pressure
The inlet pressure for PAHT 256/308 must be min.
2 barg (29 psig) and max. 6 barg (87 psig). At
lower pressures the pump will cavitate, resulting
in damage of the pump.
Max. inlet pressure peak (e.g. in case the pump
stops momentarily) up to 10 barg (145 psig) are
acceptable. Max. pressure on the pump’s outlet
line should be limited at 120 barg (1740 psig) con-
tinuously.
NB: The pump unit should include a pressure
gauge on the high pressure side.
5.3 Dry running
When running, the pump must always be
connected to the water supply in order to avoid
damage if it should run dry.
5.4 Disconnection
If the inlet line is disconnected from the water
supply, the pump will be emptied of water
through the disconnected inlet line. When
starting up again, follow the bleeding procedure
described under section 4, Initial start up.
5.5 Storage
When preparing the pump for long-term storage
or for temperatures below the freezing point,
flush the pump with an anti-freeze medium type
monopropylene glycol to prevent internal
corrosion or frost in the pump.
For further information on anti-freeze media,
please contact the Danfoss Sales Organization.
D
Instruction
