Grundfos CR 155 - 4 Selection and Sizing

Selection and sizing
CR, CRN 95-155
4
14
4. Selection and sizing
Selection of pumps
Selection of pumps must be based on these
parameters:
• the duty point of the pump (see below)
• sizing data such as pressure loss as a result of
height differences, friction loss in the pipes, pump
efficiency (see below)
• pump materials (see page 15)
• pump connections (see page 15)
• shaft seal (see page 15).
Duty point of the pump
From a duty point, you can select a pump on the basis
of the curve charts in section Performance curves and
technical data, page 22.
Fig. 7 Example of a curve chart
Sizing data
When sizing a pump, take these parameters into
account:
• Required flow and pressure at the draw-off point.
• Pressure loss as a result of height differences
(H
geo
).
• Friction loss in the pipes (H
f
).
It may be necessary to account for pressure loss in
connection with long pipes, bends or valves, etc.
• Best efficiency at the estimated duty point.
• NPSH value.
For calculation of the NPSH value, see Minimum
inlet pressure, NPSH, page 16.
Pump efficiency
Before determining the best efficiency point, identify
the operation pattern of the pump. If the pump is
expected to operate at the same duty point, select a
CR pump which is operating at a duty point
corresponding to the best efficiency of the pump.
Fig. 8 Example of a CR pump’s duty point
TM06 5537 3718
0 50 100 150 200 250 300 350 400 450 500 550 600
Q [US GPM]
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
[ft]
H
0 20 40 60 80 100 120 140
Q [m³/h]
0
20
40
60
80
100
120
140
160
180
200
[m]
H
CR 95
60 Hz
ISO 9906:2012 Grade 3B
-5-1
-5-2
-1
-1-1
-2
-2-1
-2-2
-3
-3-1
-4
-3-2
-4-2
-4-1
0 50 100 150 200 250 300 350 400 450 500 550 600
Q [US GPM]
0
5
10
15
20
[hp]
P2
0
20
40
60
80
[%]
Eff
0
4
8
12
[kW]
P2
P2
1/1
IS 3550 rpm
P2
2/3
IS 3550 rpm
Eff 3550 rpm
0 50 100 150 200 250 300 350 400 450 500 550 600
Q [US GPM]
0
40
80
120
160
[ft]
H
0
10
20
30
40
[m]
H
0
10
20
30
40
[ft]
NPSH
0
2
4
6
8
10
12
[m]
QH
1/1
IS 3550 rpm
QH
2/3
IS 3550 rpm
NPSH 3550 rpm
TM06 5537 3718
0 50 100 150 200 250 300 350 400 450 500 550 600
Q [US GPM]
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
[ft]
H
0 20 40 60 80 100 120 140
Q [m³/h]
0
20
40
60
80
100
120
140
160
180
200
[m]
H
CR 95
60 Hz
ISO 9906:2012 Grade 3B
-5-1
-5-2
-1
-1-1
-2
-2-1
-2-2
-3
-3-1
-4
-3-2
-4-2
-4-1
0 50 100 150 200 250 300 350 400 450 500 550 600
Q [US GPM]
0
5
10
15
20
[hp]
P2
0
20
40
60
80
[%]
Eff
0
4
8
12
[kW]
P2
P2
1/1
IS 3550 rpm
P2
2/3
IS 3550 rpm
Eff 3550 rpm
0 50 100 150 200 250 300 350 400 450 500 550 600
Q [US GPM]
0
40
80
120
160
[ft]
H
0
10
20
30
40
[m]
H
0
10
20
30
40
[ft]
NPSH
0
2
4
6
8
10
12
[m]
QH
1/1
IS 3550 rpm
QH
2/3
IS 3550 rpm
NPSH 3550 rpm
Duty
point
Best
efficiency