Grundfos SQ 1, Инструкция по установке и эксплуатации

Страница: 17 / 27

8. Start-up
Make sure that the well is capable of yielding a
minimum quantity of water corresponding to the pump
capacity.
Do not start the pump until it is completely submerged
in the liquid.
Start the pump and do not stop it until the pumped
liquid is completely clean, as otherwise the pump
parts and the non-return valve may choke up.
9. Operation
9.1 Minimum flow rate
To ensure the necessary cooling of the motor, the
pump flow rate should never be set to a value lower
than 50 l/h.
If the flow rate suddenly falls, the reason might be
that the pump is pumping more water than the
borehole can yield. The pump must be stopped and
the fault corrected.
The pump dry-running protection is effec-
tive only within the recommended duty
range of the pump.
9.2 Selection of diaphragm tank and setting
of precharge pressure and pressure
switch
WARNING
Pressurised system
Death or serious personal injury
‐
The installation must be designed for
the maximum pump pressure.
As the pump has a built-in soft starter giving a run-up
time of 2 seconds, the pressure at the pressure
switch and diaphragm tank during starting will be
lower than the pump cut-in pressure set on the
pressure switch (Pcut-in). This lower pressure is
called minimum pressure (Pmin).
Pmin is equal to the desired minimum pressure at the
highest tap + head and head loss in the pipe from the
pressure switch and diaphragm tank to the highest
tap (Pmin = B + C). See fig. Diaphragm tank and
pressure switch.
A
B
C
1
2
3
4
5
7
6
Q
TM006445
Diaphragm tank and pressure switch
Pos. Description
1 Ppre
2 Pmin
3 Pcut-in
4 Pcut-out
5 Qmax
6 Diaphragm tank
7 Pressure switch
A: Head + head loss from dynamic water level to
diaphragm tank.
B: Head + head loss from diaphragm tank to highest
tap.
C: Minimum pressure at highest tap.
Make sure that the selected pump can de-
liver a pressure higher than Pcut-out + A.
Ppre: Precharge pressure of diaphragm tank.
Pmin: Desired minimum pressure.
Pcut-in: Cut-in pressure set on pressure switch.
Pcut-out: Cut-out pressure set on pressure switch.
Qmax: Maximum flow at Pmin.
17
English (GB)