How should Roots blower be selected?

How to select Roots blower?

01 Application of overcurrent relay During the operation of roots blower, due to improper operation or other reasons, the motor is often burned out. In order to ensure safe operation and prevent accidents, the system shall be equipped with necessary safety protection devices. The overcurrent relay has simple structure, convenient installation and reliable use. It is a common motor overload protection device.

Before use, the current of the overcurrent relay and the time required to stop the motor after the motor current overload can be set according to the rated current of the motor. If Roots blower operates under overpressure, or friction occurs between rotor and casing (wallboard), the motor will be overloaded and the current will increase. When the motor current exceeds the rated current, the overcurrent relay will act to stop the motor within the specified time, so as to ensure that the motor will not be burned after the current overload, and the internal friction of roots blower will not further deteriorate.

The 02 safety valve acts as an overpressure protection device. Usually, the low-pressure safety valve is installed on the exhaust pipe of roots blower, and the vacuum safety valve is installed on the inlet pipe of vacuum pump. When the pressure (or negative pressure) in the pipeline exceeds the allowable value, the valve will be opened and discharged in full to prevent the pressure from rising further. When the pressure drops to the specified value, the valve shall be closed in time. The valve opening pressure can be set according to the rated working pressure of the blower, and adjusted by rotating the screw rod and changing the pre tightening compression amount of the spring.

03 In practice, low-pressure bursting discs can also be installed on the exhaust pipe of the blower. Due to the low working pressure, there will be a large error in determining the thickness of the bursting disc by the calculation method, so the bursting disc is usually trial produced on a press. The thickness of the aluminum plate used to manufacture the bursting disc is generally 0.2~0.3mm. Rotate the handle of the press and use the lower die to press the cross marks on the aluminum plate to form several test pieces with different depths. The bursting disc that has passed the pressure test can be put into use.

The control system with computer as the core is generally composed of programmable logic controller (PLC) and automatic detection instrument.

Common control switches are: (1) Temperature switch. It mainly controls the exhaust temperature and lubricating oil temperature of the blower. When the temperature reaches the switch calibration value, the switch will act (alarm or shutdown) to protect the blower from damage.

(2) Pressure switch. It mainly controls the exhaust pressure (or vacuum).

When the pressure exceeds the calibrated value of the switch, the switch will act, give an alarm or stop automatically. The pressure trend monitoring function can also be set on the software program. When the blower load increases sharply due to sudden failure, it will alarm in time to ensure the safe operation of the blower within the limited pressure range