Pump With Double Seal; Bare-Shaft Pumps - Grundfos CR Serie Montage- Und Betriebsanleitung

7.3 Pump with double seal

Back-to-back or tandem
7.3.1 Non-flammable liquids, pump unit
Category 2G/D
Make sure that the pump is filled with pumped liquid
during operation. If this is not possible, ensure
appropriate monitoring, for example dry-running
protection to stop the pump in case of malfunction.
Category 3G/D
No additional monitoring, such as dry-running
protection, is required for the pump system.
7.3.2 Flammable liquids, pump unit
Category 2G/D/M2 and 3G/D/M2
Make sure that the pump is filled with pumped liquid
during operation. If this is not possible, ensure
appropriate monitoring, for example dry-running
protection to stop the pump in case of malfunction.
Ensure sufficient ventilation around the pump.
The leakage rate of a shaft seal is 1-10 ml for each
24 hours of operation. For some types of liquids, the
leakage will not be visible due to evaporation. During
the run-in period, larger leakage of 1-20 ml per 24
hours of operation can occur. Liquids like oil or
glycol-water mixtures evaporate slower than water
and will leave residuals. Ensure proper ventilation to
maintain the zone classification.
Category M2
Protect the pump by a guard to prevent damage from
falling or ejected objects.

7.4 Bare-shaft pumps

Bare-shaft pumps with motors of 4 kW and up must
use angular contact bearings.
However, if the pumps are fitted with a thrust
handling device (THD) or a bearing flange, they must
never be used with angular contact bearings. If in
doubt, contact Grundfos.
Check if the pump is fitted with a thrust
handling device (THD). If the pump is a
THD marked pump, follow the instructions
below.
The thrust handling device (THD) is factory-fitted on
CR, CRN 95-255 for motor sizes of 75 kW and
above.
12
7.4.1 Bare-shaft pumps with a thrust handling
device
DANGER
Explosion risk
Death or serious personal injury
- Temperature monitoring of the motor
bearings is required to ensure that the
pump stops in case of overheating.
DANGER
Explosion risk
Death or serious personal injury
- Do not use ATEX motors with angular
contact bearings on pumps fitted with a
thrust handling device (THD).
DANGER
Explosion risk
Death or serious personal injury
- Temperature sensors must be installed
by qualified persons in accordance with
local regulations.
Minimum flow rate
Due to the risk of overheating, do not use the pump
at flows below the minimum flow rate.
The curve below shows 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. 3 Minimum flow rate in percentage of
nominal flow