Pressure Setting; Shaft Seal Run-In - Grundfos SCALA2 Instructions Manual

7.3 Pressure setting

The pump can be set to provide a water pressure between 1.5 to
5.5 bar (22 to 80 psi) at intervals of 0.5 bar (7 psi).
The factory setting is 3 bar (44 psi). See section System sizing.
We recommend to use the default pressure of 3.0 bar (44
psi) which will suit most applications.
The difference between the inlet pressure and outlet pres-
sure must not exceed 3.5 bar (51 psi).
Example: If the inlet pressure is 0.5 bar (7 psi), the maxi-
mum outlet pressure is 4 bar (58 psi).
If you set the pressure too high, this might cause the
pump to operate for up to three minutes after the tap is
turned off.
You can achieve more energy efficient operation and pro-
long the life of the pump by making sure that the tank pre-
charge pressure is optimised to 70 % of the setpoint of the
pump. See the table below for recommended optimal tank
precharge pressure.
Optimal tank precharge pressure
Setpoint Optimal tank precharge pressure setting
[bar (psi)] [bar (psi)]
3.9 (57) *
5.5 (80)
3.5 (51) *
5 (73)
3.2 (46) *
4.5 (65)
4 (58) 2.8 (4.1)
3.5 (51) 2.5 (36)
3 (44) 2.1 (30)
2.5 (36) 1.8 (26)
2 (29) 1.4 (20)
1.5 (22) 1.1 (16)
* Only with positive inlet pressure.
Related information
4.2 System sizing
7.3.1 Boosting from a well or a tank
If you are boosting from a well or a tank, make sure not to set the
pressure setpoint too high. The difference between the inlet
pressure and outlet pressure must not exceed 3.5 bar (51 psi).
Maximum setpoint
Well application
Tank below ground level
Tank above ground level
Boosting from a well or a tank
14
7.3.2 Boosting from the mains
The pressure settings 4.5, 5.0 and 5.5 bar (65, 73 and 80 psi)
require a positive inlet pressure and these settings must only be
used when boosting from the water mains.
Boosting from the mains
7.3.3 Self-learning setpoint
If the pump cannot reach the user-defined pressure setpoint, the
self-learning function will automatically lower the setpoint.
Related information
10.3.2 Self-learning function

7.4 Shaft seal run-in

The shaft seal faces are lubricated by the pumped liquid. A slight
leakage from the shaft seal of up to 10 ml per day or 8 to 10 drops
per hour may occur.
When the pump is started up for the first time, or when the shaft
seal has been replaced, a certain run-in period is required before
the leakage is reduced to an acceptable level. The time required for
this depends on the operating conditions, that is, every time the
operating conditions change, a new run-in period will be started.
Under normal conditions, the leaking liquid will evaporate. As a
result, no leakage will be detected.
The leakage is visible where the screws are mounted on the base
plate. If the unlikely event of an internal leakage occurs, the liquid
will be drained through the bottom of the pump. Install the pump in
such a way that no undesirable collateral damage can arise.
[bar (psi)]
3.0 (44)
3.5 (51)
4.0 (58)