Maximum Operating Pressure; Minimum Inlet Pressure; Maximum Inlet Pressure; Minimum Flow Rate - Grundfos Fire HSEF FM Europe Series Installation And Operating Instructions Manual

15.5 Maximum operating pressure

The pumps are designed for a maximum operating pressure of
12 bar (175 PSI).

15.6 Minimum inlet pressure

The minimum inlet pressure "H" in metres head required at the
suction port of the pump during operation to avoid cavitation in
the pump can be calculated from the following formula:
H = p x 10.2 - NPSH - H - H
b f v
Barometric pressure in bar. (The barometric pressure
can be set to = 1 bar.)
p
b
In closed systems, p
b
bar.
Net Positive Suction Head in metres head (to be read
from the NPSH curve at the highest flow the pump will
NPSH
be delivering).
You can read it from the curves in the data booklet.
H Friction loss in suction pipe in metres head.
f
Vapour pressure in metres head, with t
H
v
temperature. See fig. 31.
HSEF pumps according to EN
H
s
Safety margin = minimum 1.0 metres head.
If the calculated value of "H" is positive, the pump can operate
with a maximum suction lift of "H" metres.
If the calculated value of "H" is negative, a minimum suction head
of "H" metres is required.
Relation between vapour pressure and liquid temperature t
tm
(°C)
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Fig. 31 Vapour pressure scale
- H
s
is equal to the system pressure in
= liquid
m
Hv
(m)
45
40
35
30
25
20
15
12
10
8,0
6,0
5,0
4,0
3,0
2,0
1,5
1,0
0,8
0,6
0,4
0,3
0,2
0,1

15.7 Maximum inlet pressure

The actual inlet pressure and closed-valve pressure must always
be lower than the maximum operating pressure. See section
15.5 Maximum operating pressure.
You find the closed-valve pressure of the pump in the data
booklet of the pump set.

15.8 Minimum flow rate

The pump must not run against a closed valve as this
Caution
may cause an unacceptable temperature increase or
formation of vapour.
In pump sets with a water-cooled diesel engine, a minimum flow
rate of the pump is ensured by a pipe connecting the pump
discharge port with the engine heat exchanger.

15.9 Pump speed

The pump speed is stated on the nameplate.

15.10 Direction of rotation

The direction of rotation of the pump is clockwise when seen from
the drive end. The correct direction of rotation is indicated by an
arrow on the pump housing.

15.11 Liquid and ambient temperature

Liquid temperature
The pump is designed for liquid temperatures up to 120 °C.
Pump set with water-cooled diesel engine:
The maximum liquid temperature depends on the
m
Note
coolant temperature required to cool the diesel
engine. See installation and operating instructions for
the diesel engine.
Ambient temperature
The maximum permissible ambient temperature depends on the
driver and controller. See installation and operating instructions
for the driver and controller.

15.12 Relative air humidity

The relative air humidity must not exceed 80 %. Otherwise the
controller may be damaged. If humidity is a problem, install a
space heater with a hydrostat.
25