Slide valve vacuum pump

Valve type oil sealed mechanical pump (abbreviated as slide valve pump), like rotary vane pump, is also a variable volume gas transfer pump, but compared with 2X rotary vane vacuum pump, slide valve vacuum pump is several times more durable. Its scope and usage conditions are basically the same as those of rotary vane pumps. The slide valve vacuum pump is divided into two models: single-stage H-type and bipolar 2H type. The older ones include MH and 1401 series, which have been basically eliminated.

Brief introduction

Due to its structural characteristics and much larger capacity than rotary vane pumps, slide valve pumps are often used in large vacuum equipment. There are two types of slide valve pumps: single-stage and two-stage. The maximum pressure of a single-stage pump is ≤ 0.6Pa for a small pump and ≤ 1.3Pa for a large pump (with gas lock off), while the maximum pressure of a two-stage pump is ≤ 0.06Pa (with gas lock off). The maximum pumping speed of the bipolar 2H slide valve vacuum pump is 300L/S.

Due to the large eccentricity of the rotating mass of the slide valve pump, if the slide valve is not well balanced in mass, it will produce significant vibration during operation. However, the motion trajectory of the pump's rotational center of mass is a complex closed curve, making it difficult for small factories to achieve complete balance of the inertia force of the slide valve pump. The mass balance of the slide valve can be achieved through dynamic balance testing and dual or triple cylinder structures.

Structure and Characteristics

The Roots slide valve vacuum unit is a vacuum unit composed of a regular Roots pump as the main pump and a slide valve vacuum pump as the front stage pump in series. Automatic opening and closing of Roots pump slide valve pump and automatic overload protection are achieved through vacuum relay or electric contact pressure gauge. The entire unit is installed on a rack, equipped with pipelines, valves, electrical control boxes, and cooling water pipe systems. The unit has a compact structure and is easy to use.

According to the size and ultimate pressure of the vacuum system being evacuated, the nominal pumping speed ratio between the pumps of the vacuum unit is generally between 4:1 and 10:1. The former is more suitable for larger vacuum systems and long-term operation under lower inlet pressure or ultimate vacuum conditions than the latter. In order to prevent oil return when the slide valve pump stops, this series of units is equipped with an electromagnetic inflation valve on the inlet pipeline of the front stage. Its action is linked with the motor of the front stage pump. Before the slide valve pump stops, it inflates the pump port to ensure that the vacuum oil in the slide valve pump returns to the oil tank and prevent the vacuum system from being contaminated by vacuum oil.

Application

The Roots slide valve vacuum unit has significant energy-saving effects, high vacuum degree, and large pumping volume in high vacuum intervals. It can be widely used in the vacuum impregnation and vacuum drying processes of transformers, wires and cables, and capacitors in the power industry.

It can also be used as vacuum equipment for vacuum coating, vacuum smelting, vacuum heat treatment, vacuum oil filtration, and freeze-drying.