Rotary vane vacuum pump start and stop

Usually the rotary vane vacuum pump is driven by a three-phase alternating current. Also do not pay attention to the power line link to ensure the correct direction of rotation, otherwise, the pump oil will be discharged to the vacuum chamber. Therefore, the pump should be set to reverse braking to prevent the pump from reversing. When the wrong power cord is connected, the pump will not start. In order to prevent the motor from being burned out, an overload switch should also be provided, usually a temperature-controlled switch.

When the pump is stopped, the pressure of the outlet air will reverse the pump, causing the pump oil to fall back into the vacuum chamber and air will enter the vacuum chamber to destroy the vacuum. Therefore, special valves are required to separate the pump from the vacuum chamber to prevent air and pump oil from entering the vacuum chamber. The installed protection valve is located in the pump inlet pipe. Its role is to close the pipe between the vacuum chamber when the pump is de-energized or the control switch is off, and to deflate the pump inlet. This kind of protection valve is usually an electromagnetic valve. It is connected to the motor power supply to control the entry of air. When the motor is de-energized, the solenoid valve opens and the pressure difference between the atmosphere and the pump inlet closes the channel between the pump and the vacuum chamber, and the atmosphere enters the pump inlet. When the pump starts, the solenoid valve closes, the pump evacuates the protection valve, and the valve plate is opened by spring pressure. In a typical rotary vane pump, an air isolation valve is often provided in the pump inlet, and the air passage is used to protect the valve. At this time, there is no need to install an electromagnetic bleed valve on the inlet pipe.