| DOC9091B
17
Truck Master 1700
3.7 Water requirement
3.6 Cavitation
Vacuum
50%
75%
80%
90%
Temperature °C
80
64
59
44
Maximum discharge temperature
70
50
40
30
Note that the temperature of the gas inside the pump will heat up the water and the water surface therefore
will become a higher temperature than the measured temperature on the discharge side of the pump.
Cavitation will therefore start at a lower temperature and the maximum discharge temperature of the water
must be kept lower.
DOC1627506
DOC1627506
Below you find the boiling point of water as a function of the pressure.
When the temperature reaches the boiling point of the water, steam bobbles will be created in the liquid
ring.
These bobbles cannot exist when they enter the discharge side of the pump and therefore they will
collapse. The impact force on the surface of the rotor and flow plate will damage the pump and can lead to
a total breakdown. It is a very harmful situation that must be avoided.
It is the combination of the pressure and the temperature that will lead to the cavitation. Therefore, it is
recommended to install a vacuum control valve, see illustration below that shows a clockwise rotating
pump. If counter-clockwise rotating pump, mount in opposite manifold.
During operation it is normal that small amount of product will enter the pump, or the gas will react with
the water which can become aggressive.
Drain the liquid separator and refill with fresh water, if the water has become aggressive.