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11. Technical data
11.1 Hydraulic data
Minimum pre-pressure:
The minimum pre-pressure “H” in metres head required to avoid
cavitation in the pumps is calculated as follows:
H = p
b
x 10.2 – NPSH – H
f
– H
v
– H
s
p
b
= Barometric pressure in bar.
Barometric pressure can be set to 1 bar.
NPSH = Net Positive Suction Head in metres head
(to be read from the NPSH curve at the highest flow).
See installation and operating instructions for
CR pumps.
H
f
= Friction loss in suction pipe in metres head.
H
v
= Vapour pressure in metres head, t
m
= liquid
temperature.
See installation and operating instructions for
CR pumps.
H
s
= Safety margin of minimum 0.5 metres head.
Note: During operation, pressure drops in the manifold will in-
crease the required minimum pre-pressure.
Maximum pre-pressure:
See installation and operating instructions for CR pumps.
11.2 Operating conditions
Liquid temperature: Maximum +70°C.
Ambient temperature: 0°C to +40°C.
Operating pressure: Maximum 16 bar.
11.3 Sound pressure level
For sound pressure level, see installation and operating instruc-
tions for the CR pumps.
The sound pressure level for a number of pumps can be calcu-
lated as follows:
L
max.
= L
pump
+ (n – 1) x 3
L
max.
= Maximum sound pressure level.
L
pump
= Sound pressure level for one pump.
n = Number of pumps.
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