Maintena nce
50
WBV.PU.002.EN VX215QD V2.0
8.4
Circulation system on the cartridge mechanical seal
The cartridge mechanical seal is flushed by a circulation system. The flushing liquid, e.g. oil, water or
glycerine, must be compatible with the pump medium.
Technical prerequisites for the circulation system
•
Flushing connectors (1) on the pump
Fig.
"Flushing operation".
•
Cartridge mechanical seal with the "double mechanical seal" arrangement. The selection of materials
for the cartridge mechanical seal depends on the flushing medium.
Parallel
Connection example for flushing
pressure and volume flow
adjustment
In series
Connection example for flushing
pressure and volume flow
adjustment
Fig. 19: Flushing operation
Adjustment of flushing pressure and volume flow
Fig.
"Flushing operation - connection example for flushing pressure and volume flow adjustment".
Adjusting the flushing pressure
The flushing pressure can be adjusted and monitored with a pressure gauge.
The flushing pressure should be about 0.5 bar higher than the average pressure in the pump.
Flushing pressure = 0.5 bar + (pressure on the suction side + pressure on the discharge side) / 2
Example:
A pump primes with 0.4 bar suction and discharges with 2.0 bar overpressure.
Pressure on the suction side:
–0.4 bar, pressure on the discharge side: 2.0 bar
Flushing pressure = 0.5 bar +
2
)
bar
2
bar
4
,
0
(
= 1.3 bar
In this example, the flushing pressure is 1.3 bar.
If there is an increased risk that medium will get between the sliding surfaces, the pressure should be
increased by 1 bar (in the example: 1.3 bar + 1 bar).
Independently of this, the flushing pressure should be no more than 10 bar with a double mechanical seal.
