Barrier Or Flushing Liquid; Liquid Connections Of Dead-End Solutions; Circulating Solution; Vacuum Operation Or Suction Lift - Grundfos NK series Montage- Und Betriebsanleitung

5.3 Barrier or flushing liquid

Barrier or flushing liquid must have an auto-ignition
temperature which is at least 50 K higher than the
maximum surface temperature of the pump.
5.4 Liquid connections of dead-end
solutions
Pressureless
dead-end liquid
Fig. 6 Examples of double seal arrangements
with dead-end solutions
For the examples in fig. 6, the liquid must
be connected to pipe connection number 2
in fig. 7. Pipe connections 1 and 3 must be
plugged. See fig. 7.
1
2
Fig. 7 Pipe connections
12
Pressurised
dead-end liquid
3

5.5 Circulating solution

Fig. 8 Example of circulating solution
Important operating parameter for the circulating
solution:
At all times, the maximum discharge temperature
from the seal chamber must be kept below 70 °C,
and optimally maximum 60 °C.
Delta T across the seal chamber is adjusted and set
between 7 and maximum 10 K.

5.6 Vacuum operation or suction lift

Fig. 9 Pumps with double seal arrangements
connected to an elevated vessel
If vacuum operation or suction lift is a continuous or
periodic operating condition for the applications
shown in fig. 9, use appropriate level monitoring
equipment to ensure liquid in the seal chamber. The
pump must be stopped if the liquid reaches a
specified low level in the supply vessel.