should be shut down to check the limit vacuum of the rotary vane vacuum pump. the compressed vacuum gauge should be used. the vacuum gauge should be directly connected to the rotary vane vacuum pump port and will reach the limit vacuum within 30 minutes. before starting, check whether the cooling water of the water-cooled pump can be connected. when the ambient temperature is low, the belt pulley can be moved by hand so that the oil in the pump chamber can be discharged into the tank. then press the motor button to send electricity, pay attention to whether the power direction can be reversed, and whether the rotation direction 