During the operation of the Roots blower, due to improper operation or other reasons, there are often incidents in which the motor burns out or the blower is destroyed. In order to ensure operational safety and prevent accidents, the system should have the necessary safety protection devices.

1. Application of overcurrent relays

The overcurrent relay is a commonly used motor overload protection device because of its simple structure, easy installation and reliable use. Before use, the current of the overcurrent relay can be set according to the size of the motor's rated current, as well as the time required to stop the motor after the motor current is overloaded. If the blower is running at overpressure, or if the rotor is rubbing against the housing (wall plate), etc., the motor will be overloaded and the current will increase. When the motor current exceeds the rated current, the overcurrent relay will generate an action to use the motor within the specified time without burning up after the current overload, and the internal friction of the blower without further deterioration.

2. Application of safety valves

As overpressure protection devices, low-pressure safety valves are usually installed in the blower discharge line and vacuum installation valves are installed in the vacuum pump inlet line. When the pressure (or negative pressure) in the pipeline exceeds the permissible value, the valve opens and discharges the full amount to prevent the pressure from continuing to rise. When the pressure is reduced to the specified value, the valve is 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 and changing the spring preload compression.

3. Low Pressure Rupture Disc Applications

In practice, low-pressure rupture discs can also be installed in the blower exhaust line. Due to the low operating pressure, the thickness of the rupture disc can be determined by calculation with a large margin of error. Rupture discs are pilot manufactured in a press. The thickness of the aluminum plate used to manufacture the rupture disc is generally 0.20 to 0.30 mm. The press handle is rotated, and the lower die is used to press the cross marks on the aluminum plate, which are pressed into several test pieces of different depths. After the test pressure qualified rupture disc, can be put into application.

4. Computer-centered control systems

It generally consists of two main parts: a programmable controller (PLC) and an automatic detection meter. Common control switches are:

• Temperature Switch. Primarily controls the blower's exhaust temperature and lubricating oil temperature. When the temperature reaches the switch calibration value, the switch is actuated (alarm or shutdown) to protect the blower from damage.
• Pressure switch. Mainly controls the exhaust pressure (or vacuum pumping degree). When the pressure exceeds the switch calibration value, the switch operates, alarms or automatically stops. Pressure trend monitoring capability can also be set on the software program. When the blower load increases dramatically due to sudden failure reasons, the alarm will be given in time to ensure the safe operation of the blower within the limited pressure range.