Maintena nce
44
WBV.PU.002.EN VX186QD V2.0
Tank pressure
The tank pressure should be about 0.5 bar higher than the average pressure in the pump.
Tank 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.
Tank pressure = 0.5 bar +
2
)
bar
2
bar
4
,
0
(
= 1.3 bar
In this example, the tank pressure is 1.3 bar.
Regardless of this, the tank pressure should not exceed 5 bar with a single mechanical seal and should not
exceed 10 bar with a double mechanical seal.
Rotary lobe change and Cartridge mechanical seal change
Before a rotary lobe and Cartridge mechanical seal change, reduce the
tank pressure
and increase it again
after changing.
Trouble indication
Possible indications of trouble in the sealing system after the running-in period:
•
Severe contamination of the buffer fluid in the tank
•
Buffer fluid escaping (tank is empty)
•
Increase in buffer fluid level (tank is full)
Buffer fluid characteristics
•
The hydrodynamic lubrication film of a mechanical seal can cause:
Slight contamination of the buffer fluid
A slight increase or reduction in the buffer fluid level
•
A slight increase in the buffer fluid level is also possible due to thermal expansion during pump
operation.