Viscosity selection principle
The selection of oil viscosity is one of the most important factors for the performance of the vacuum pump. The viscosity of the liquid is the resistance of the liquid flow, or the internal friction of the liquid. If the greater the viscosity, the greater the resistance of the movement velocity of various components, resulting in increased temperature rise and power loss. In addition, the viscosity is too small and the sealing performance of the pump becomes worse, which leads to the leakage of gas and the deterioration of vacuum. Therefore, various kinds of vacuum pump viscosity of the oil are extremely important choice, and the principle of choosing oil viscosity is:
(1) The higher the speed of the pump, the lower the viscosity of the selection of oils.
(2) The greater the pump rotor motion linear velocity, the lower the viscosity of the selected oil.
(3) The more precise the machining accuracy of the pump parts or the smaller the gap between the friction members, the lower the viscosity of the selected oil.
(4) When the vacuum pump is used in the high temperature condition, the choice of the higher the viscosity of the oil the better.
(5) The vacuum pump with cooling water circulation, it is best to choose oil with lower viscosity.
Recommended vacuum oil viscosity scope
According to these principles, the viscosity range of various types of vacuum pump oils is recommended as follows:
(1) The piston vacuum pump (W type) can use the general machine oil, with V100, V150 viscosity grade oil.
(2) The rotary vane vacuum pump (2X type) selects V68 and V100 viscosity grade oil.
(3) The direct joint (high speed) rotary vane vacuum pump (2XZ type) selected V46, V68 viscosity grade oil.
(4) The slide valve type vacuum pump (H type) selects V68 and V100 viscosity grade oil.
(5) The residual cycloid vacuum pump (YZ, YZR) selected V100, V150 viscosity grade oil.
(6) The lubrication of the roots of the roots vacuum pump (supercharged pump) gear transmission system, V32, V46 vacuum pump oil can be selected.
(7) Other types of vacuum pumps can be selected the corresponding oil, according to the rotational speed, machining precision, and extreme vacuum.