Maximum Inlet Pressure; Minimum Flow Rate; Electrical Data; Frequency Of Starts And Stops - Grundfos CRT Serie Instrucciones De Instalación Y Funcionamiento

5.4 Maximum inlet pressure

Fig. B on page 129 shows the maximum inlet pressure. However,
the actual inlet pressure + maximum pump pressure (at no flow)
must always be lower than the values stated in Appendix on
page 128.
The pumps are pressure-tested at a pressure of 1.5 times the
values stated in Fig. B on page 129.

5.5 Minimum flow rate

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.
Qmin
[%]
30
20
10
0
40 50 60 70 80 90 100 110 120 t [°C]
Fig. 4 Minimum flow rate
The pump must not run against a closed
Caution
discharge valve.

5.6 Electrical data

See motor nameplate.

5.7 Frequency of starts and stops

Motor size Maximum number of starts per hour
≤ 3 kW
4 to 18.5 kW

5.8 Dimensions and weights

Dimensions: See Fig. C on page 129.
Weights: See label on the packing.

5.9 Sound pressure level

See Fig. D on page 130.
200
100

6. Installation

The pump must be secured to a horizontal, plane and solid
foundation by bolts through the holes in the base plate.
When installing the pump, follow the procedure below in order to
avoid damaging the pump.
Step
1
2
4 x ø
L
B
1
1
L
B
2
2
3
4
5
6
Action
Arrows on the pump base show
the direction of flow of liquid
through the pump.
These pieces of information are
stated in Fig. C on page 129:
• port-to-port lengths
• dimensions of the base
• pipework connections
• diameter and position of
foundation bolts.
The pump can be installed
vertically or horizontally.
However, the motor must
neither fall below the horizontal
plane nor be installed upside
down.
Ensure that an adequate supply
of cool air reaches the motor
cooling fan.
Motors above 4 kW must be
supported.
To minimise possible noise from
the pump, we advise you to fit
expansion joints on either side
of the pump. The foundation/
installation must be carried out
as described in section 6.1.
Fit isolating valves on either
side of the pump to avoid
draining the system if the pump
needs to be removed for
cleaning, repair or replacement.
Always protect the pump
against backflow by means of a
non-return valve (foot valve).
Install the pipes so that air locks
do not occur, especially on the
suction side of the pump.
Fit a vacuum valve close to the
pump if the installation has one
of these characteristics:
• The discharge pipe slopes
downwards away from the
pump.
• There is a risk of siphon
effect.
• Protection against backflow of
unclean liquids is needed.
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