Grundfos CR 155 - How to Read the Curve Charts

Selection and sizing
CR, CRN 95-155
4
17
How to read the curve charts
Fig. 15 How to read the curve charts
Guidelines to performance curves
The guidelines below apply to the curves shown on the
following pages:
• Tolerances to ISO 9906:2012, Grade 3B, if
indicated.
• The motors used for the measurements are
standard Grundfos motors.
• Measurements have been made with airless water
at a temperature of 68 °F (20 °C).
• The curves apply to the following kinematic
viscosity:  = 1 mm
2
/s (1 cSt).
• Due to the risk of overheating, the pumps must not
be used at a flow rate below the minimum flow rate.
• The QH curves apply to a rated motor speed of a
three-phase mains-operated motor. For realistic
curves, go to Grundfos Product Center
(http://product-selection.grundfos.com/) and insert
data.
The curve below shows the minimum flow rate as a
percentage of the rated flow rate in relation to the
liquid temperature. The dotted line shows a CR pump
fitted with an air-cooled top assembly.
Fig. 16 Minimum flow rate
TM06 5538 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
CRN 95
60 Hz
ISO 9906:2012 Grade 3B
-5-2
-5-1
-1
-1-1
-2
-2-1
-2-2
-3
-3-1
-3-2
-4
-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
Pump type, frequency and ISO standard.
Number of stages.
First figure: number of stages.
Second figure: number of
reduced-diameter impellers.
The power curves indicate pump
input power per stage.
Curves are shown for complete
(1/1) and for reduced-diameter
(2/3) impellers.
QH curve for the individual pump.
The bold curves indicate the
recommended duty range for
best efficiency.
The eta curve shows the efficiency
of a pump with three full size
impellers.
The efficiency of pumps with
reduced-diameter impellers is
approximately 2 % lower than the
eta curve shown in the chart.
The NPSH curve is a maximum
curve for all the variants shown.
TM07 0517 0118
104 140 176 212 248 284 320 356
0
10
20
30
Qmin
(40) (60) (80) (120) (140) (160) (180)(100)
[ % ]
t
[°F]
[(°C)]