Vacuum unit is chosen as the backing pump water ring pump more advantageous than other vacuum pump, it overcomes the single water ring pump when using the limit pressure difference (extreme pressure of the unit has greatly improved than water ring pump), a disadvantage of low extraction rate under certain pressure, while retaining the water pump can work quickly, has the advantages of larger extraction rate.
In order to make the volume of the unit as small as possible, we can try to make the steam to be pumped condense before entering the pump unit, so that what is left is non-condensable gas and trace residual steam.A gas decreases in volume at the same pressure as it cools down.Therefore, the amount of pumping required after condensation is reduced, and the pump can be selected accordingly.