Low vacuum devices such as vacuum transportation, vacuum impregnation, vacuum filtration, vacuum monotony and vacuum degassing (molten steel treatment) require low vacuum pump {pumping units with high operating pressure and large displacement. The main pumps of this low vacuum pumping unit are reciprocating vacuum pump, oil sealed vacuum pump, steam radiation pump, water ring pump, roots pump, etc. The low vacuum air extraction unit used shall also be equipped with essential dust removal equipment, monotone tank and other parts according to the cleanliness, humidity or other special requirements of the extracted gas.

  Water vapor will condense into water droplets in the compression process and mix with the pump to form a suspension, which will not only reduce the vacuum, but also rust the pump cavity and rotor, damage the sealing surface and reduce the ultimate vacuum of the pump. Therefore, it is very important to prevent water vapor from polluting the mechanical pump. Preventive measures include:

(1) Select oil sealed mechanical pump with air ballast device;

(2) The oil separator, centrifugal separator or oil-water separator will stop the treatment of the mechanical pump oil mixed with water, and the treated oil will flow into the pump for use;

(3) Use monotonic agent with strong water absorption;

(4) The use of liquid nitrogen cold trap can not only reasonably and effectively adsorb water vapor, but also block the return flow of mechanical pump oil to the high vacuum chamber.