English (GB)
7
5.2 Liquid temperature
The table on page 333 states the relationship between liquid
temperature range and maximum permissible operating pressure.
5.3 Maximum permissible operating pressure and
liquid temperature for the shaft seal
CR, CRI, CRN 1s to 20 and CR, CRN 32 to 150
Fig. 3 Maximum permissible operating pressure and liquid
temperature
You can clean CRI and CRN pumps in place (CIP) with a type H
shaft seal with EPDM rubber parts, HxxE and liquids up to 150 °C
for maximum 15 minutes.
CR, CRI, CRN pumps are not suitable for the pumping of liquids
above 120 °C for long periods.
5.4 Minimum inlet pressure
Fig. 4 Schematic view of open system with a CR pump
Calculate the maximum suction lift "H" in metres head 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.
In closed systems, p
b
indicates the system pressure in
bar.
NPSH = Net Positive Suction Head in metres head.
To be read from the NPSH curve on page 331 at the
highest flow the pump will be delivering.
H
f
= Friction loss in inlet pipe in metres head at the highest
flow the pump will be delivering.
H
v
= Vapour pressure in metres head, see fig. E on page
336. t
m
= liquid temperature.
H
s
= Safety margin = minimum 0.5 metres head.
If the calculated "H" is positive, the pump can operate at a suction
lift of maximum "H" metres head.
If the calculated "H" is negative, an inlet pressure of minimum "H"
metres head is required. There must be a pressure equal to the
calculated "H" during operation.
Example
p
b
= 1 bar.
Pump type: CR 15, 50 Hz.
Flow rate: 15 m
3
/h.
NPSH (from page 331): 1.1 metres head.
H
f
= 3.0 metres head.
Liquid temperature: +60 °C.
H
v
(from fig. E, page 336): 2.1 metres head.
H = p
b
x 10.2 - NPSH - H
f
- H
v
- H
s
[metres head].
H = 1 x 10.2 - 1.1 - 3.0 - 2.1 - 0.5 = 3.5 metres head.
This means that the pump can operate at a suction lift of
maximum 3.5 metres head.
Pressure calculated in bar: 3.5 x 0.0981 = 0.343 bar.
Pressure calculated in kPa: 3.5 x 9.81 = 34.3 kPa.
5.5 Minimum inlet pressure
The table on page 334 states the maximum permissible inlet
pressure. However, the actual inlet pressure + maximum pump
pressure (at no flow) must always be lower than the values stated
in fig. A, page 333.
The pumps are pressure-tested at a pressure of 1.5 times the
values stated in fig. B, page 334.
The maximum permissible operating pressure and
liquid temperature ranges apply to the pump only.
The diagram below applies to clean water and water
containing anti-freeze liquids.
TM03 8853 4907
Standard shaft seal
Motor
[kW]
Max. temperature range
[°C]
HQQE 0.37 - 45 -40 - 120 °C
HBQE 55-75 0-120 °C
HQQV 0.37 - 45 -20 - 90 °C
HBQV 55-75 0-90 °C
The pumping of liquids above +120 °C may result in
periodical noise and reduced pump life.
-60 -40 -20 0 20 40 60 80 100 120 140
0
5
10
15
20
25
30
35
p [bar]
HQQE/V
HBQE/V
H
Q
Q
E
H
Q
Q
E
H
B
Q
E
H
Q
Q
V
H
Q
Q
E
t [°C]
TM02 0118 3800
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