Calculate the maximum suction lift "H" in m head as
follows:
H
= Pb x 10.2 - NPSH - Hf - Hv
Pb
=
Barometric pressure in bar.
Barometric pressure can be set to 1 bar.
In closed systems, Pb indicates the sys-
tem pressure in bar.
NPSH =
Net Positive Suction Head in m head, to
be read from the NPSH curve at the high-
est flow the pump will be delivering.
Hf
=
Friction loss in the inlet pipe in m head at
the highest flow the pump will be deliver-
ing.
Hv
=
Vapour pressure for water in m head. See
Figure E.
If the pumped liquid is not water, then use
the vapour pressure for the liquid which is
being pumped.
tm
= Liquid temperature.
If the calculated "H" is positive, the pump can operate
at a suction lift of maximum "H" m head.
If the calculated "H" is negative, an inlet pressure of
minimum "H" m head is required. There must be a
pressure equal to the calculated "H" during operation.
Example
Pb = 1 bar.
Pump type: CR 15, 50 Hz.
Flow rate: 15 m
3
/h.
NPSH: 1.1 m head, from Figure A.
Hf = 3.0 m head.
Liquid temperature: +60 °C.
Hv: 2.1 m head (from Figure E).
H = Pb x 10.2 - NPSH - Hf - Hv - Hs [m head].
H = 1 x 10.2 - 1.1 - 3.0 - 2.1 - 0.5 = 3.5 m head.
This means that the pump can operate at a suction lift
of maximum 3.5 m head.
Pressure in bar: 3.5 x 0.0981 = 0.343 bar.
Pressure in kPa: 3.5 x 9.81 = 34.3 kPa.
9.1.5 Maximum permissible inlet pressure
The table in the section on the figure B in the
appendix states the maximum permissible inlet
pressure for vertically mounted pumps. However, the
actual inlet pr the maximum pump pressure
at no flow must always be lower than the maximum
permissible system pressure which is stated on the
pump nameplate. For identification of the nameplate
data, see the section on the nameplate.
The pumps are pressure-tested at a pressure of 1.5
times the maximum permissible system pressure.
Related information
9.1.6 Minimum flow rate
WARNING
Too high pressure and leakage
Death or serious personal injury
‐
Do not run the pump against a closed
outlet valve.
Due to the risk of overheating, do not use the pump at
flows below the minimum flow rate.
The curves below show the minimum flow rate as a
percentage of the rated flow rate in relation to the
liquid temperature.
- - - - = air-cooled top.
40
60
80
100
120
140
160
180
t
[°
C
]
0
10
20
30
Q
min
[ % ]
TM012816
Minimum flow rate in percentage of nominal flow
9.1.7 Frequency of starts and stops
See the instructions for the motor which are supplied
with the pump.
9.2 Dimensions and weights
Dimensions: see Figure C.
Weights: see label on the packing.
9.3 Electrical data
See the motor nameplate.
9.4 Sound pressure level
See
.
Related information
31
English (GB)
Summary of Contents for CRN 125-11
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