Limit pressure of rotary vane pump

Soon after the rotary vane pump started to work, the lowest pressure was P'g. The pump continues to operate, because the pump temperature rises, the saturated vapor pressure of the pump oil rises, the viscosity decreases, and the inlet pressure rises slightly back to Pg. Pg is the stable minimum pressure of pump and the ultimate pressure of pump.

The ultimate pressure of the rotary vane pump is related to the type of vacuum gauge used in the measurement. The limiting pressure ratio is measured by a heat conduction vacuum gauge (thermocouple or pioglitz gauge, etc.).piston-vacuum-pump-for-various-applications

The result of measurement is about one order of magnitude. This is because the former can only measure the partial pressure of the permanent gas, and the latter measured the total pressure of the compressed gas. In China, the compressibility vacuum gauge is used to measure the limit pressure of the oil seal mechanical pump.

The pump circulation oil also affects the ultimate pressure of the pump. With the increase of the oil quantity, the better the sealing effect, the relationship between the limit pressure of the pump and the oil quantity changes, and finally reaches the saturated vapor pressure Po of the oil. In fact, there is a lot of air and water in the pump oil. When the pump oil enters the pump chamber, the air and water absorbed in the pump oil are released again. The relationship between the pump limit pressure and the oil volume is developing upwards. The general pump oil should be kept at the designated oil level, so that the circulating oil volume of the pump must be maintained. For the two-stage pump, the pump oil must pass through the low vacuum stage degassing before entering the high vacuum stage, so as to reduce the pump oil in the high vacuum stage of the degassing volume, to reduce the pump limit pressure.liquid-ring-vacuum-pump-application-process-introduction

The ultimate pressure of the rotary vane pump is related to the working temperature of the pump oil. The higher the oil temperature, the higher the saturated vapor pressure of the oil, the higher the ultimate pressure of the pump.Liquid-Ring-Vacuum-Pump-Applications