Greentech International (Zhangqiu) Co., Ltd.
Greentech Industry (Jinan) Co., Ltd.
In industrial vacuum equipment, Roots vacuum pumps are widely used due to their high pumping speed and stable operation. However, the long-term stable operation of the equipment relies on scientific installation, standardized operation, and meticulous maintenance. This article systematically outlines the key points of the entire process for Roots vacuum pumps—from installation to daily use, and then to common troubleshooting—providing a practical guide for equipment managers and operators.
Proper installation is the foundation for long-term stable operation of the equipment. The installation of Roots vacuum pumps must be strictly controlled from four aspects: environment, location, piping, and electrical connections.
Clean Environment: The pump should be installed in a dry, well-ventilated, and dust-free location.
Temperature Control: The ambient temperature must be maintained between 5°C and 40°C.
Horizontal Installation: The pump body must be installed horizontally, with sufficient maintenance space reserved around it for daily inspection and disassembly.
Motor Rotation: After powering on, ensure the motor rotation direction matches the arrow on the pump body.
Inlet Piping: The pipeline connecting to the vessel being evacuated must be clean and free of impurities, with an inner diameter not smaller than the pump inlet口径, and should be as short as possible to ensure conductance. The connections must be well sealed.
Particulate Protection: Ensure that no solid particles enter the pump chamber with the gas being evacuated.
Vibration Isolation: When connecting to the backing pump, flexible piping should be used to reduce vibration transmitted from the backing pump.
Interlock Protection: The electrical system must include an interlock device: when the backing pump stops, the Roots pump must stop simultaneously.
Starting Device: Low-power pumps can be started directly, while high-power pumps require a starter.
After a new pump is installed, first check the oil level. On the gear side, the oil level should immerse 3–5 gear teeth; on the motor side, it should be slightly above the center of the oil sight glass. The shaft extension oil cup must not lack oil. No. 1 vacuum pump oil should be used for all lubrication points.
Start the backing pump.
Open the valve on the backing pump's roughing line and the inlet valve of the Roots pump.
Once the system pressure drops to the Roots pump's allowable starting pressure, close the roughing valve and start the Roots pump. This process can be automated using a pressure sensor.
Special Notes:
For non-large vacuum systems, the Roots pump can be started immediately after the backing pump is started.
For large systems, even if the Roots pump is equipped with a relief valve (which only protects the motor), it is still necessary to wait until the backing pump has evacuated to a certain pressure before starting the Roots pump. Otherwise, prolonged high-pressure operation can cause overheating and seizure.
Close the inlet valve of the Roots vacuum pump.
Shut down in sequence: Stop the Roots pumps stage by stage from top to bottom, and finally stop the backing pump. The sequence must not be reversed.
After the backing pump stops, immediately vent its inlet to atmosphere.
Pressure and Differential Pressure: The inlet pressure should preferably be below 1330 Pa, and the maximum differential pressure must not exceed the pump's allowable value.
Temperature Monitoring: Under normal conditions, the maximum temperature rise of the pump does not exceed 40°C, and the maximum temperature does not exceed 80°C. If a water-ring pump is used as the backing pump with a relatively high pumping speed, the maximum temperature must not exceed 100°C.
Abnormal Conditions: Irregular vibration, abnormal noise, motor overload, or excessive temperature rise must not occur during operation. If any of these occur, the pump must be stopped immediately for inspection.
Daily Checks: Check the oil level (too high causes temperature rise, too low causes poor lubrication) and the temperature rise/load of the pump body and motor.
Monthly Checks: Check the oil quality; replace immediately if degraded.
Periodic Overhaul: Regularly inspect wearing parts such as bearings, oil seals, and timing gears; replace them promptly if damaged.
Possible Causes:
Insufficient pump speed (incorrect pulley diameter or belt slipping).
Poor sealing (leakage at flanges or shaft seals).
Internal clearances too large, increasing backflow.
Ambient or cooling water temperature too high.
Troubleshooting Methods:
Adjust pulley diameter or tension belts.
Inspect and repair leak points (tighten flange screws, replace sealing cups or packing).
Adjust timing gears to ensure uniform rotor clearance.
Reduce cooling water or ambient temperature.
Possible Causes:
Poor sealing in the inlet system or the pump body itself.
Internal clearances too large or air temperature too high.
Excessive differential pressure across the pump (e.g., malfunctioning safety valve, excessive water seal pressure at the outlet, or high piping resistance).
Troubleshooting Methods:
Address leakage and clearance issues as described in Fault 1.
For wet pumps, inject cold water at the inlet; for dry pumps, install a cooler at the outlet.
Inspect and repair the safety valve; reduce outlet resistance.
Possible Causes (more common in wet pumps):
Excessive scale buildup on pump casing and rotor surfaces.
Hard debris (e.g., welding slag) entering the pump chamber.
Axial rotor movement causing friction against the end cover.
Bent rotor shaft, or seizure between rotors or gears.
Troubleshooting Methods:
Remove scale: Mechanically scrape off or use 5%-10% hydrochloric acid for cleaning (after acid cleaning, rinse with steam and water to prevent corrosion).
Ensure piping is clean before installation.
Reassemble the rotor; determine the cause of axial movement.
Check rotor shaft straightness; straighten if minor, replace if severe.
Possible Causes:
Friction between rotors, or between rotor and casing.
Poor timing gear meshing, excessive clearance, or insufficient lubrication.
Pump speed too high, causing violent media impact.
Troubleshooting Methods:
Readjust rotor clearances to a uniform state.
Adjust timing gear meshing and add sufficient lubricant.
Appropriately reduce speed, or install a silencer at the outlet.
Summary: The efficient operation of Roots vacuum pumps depends on every link in the chain: installation, operation, maintenance, and troubleshooting. Establishing standardized startup/shutdown procedures, adhering to daily inspections and periodic maintenance, and being able to quickly identify root causes based on fault symptoms are key to ensuring long-term, safe, and stable equipment operation. We hope this article provides practical technical references for practitioners.
Roots Blower product information
Web: http://www.greentechblower.com (Group Web) ‖ http://www.zqblower.cn (Chinese) ‖ http://www.ringblower.cn/ (Ring blower) ‖ http://www.china-blower.com (Roots Blower)
Copyright © 2025 Greentech International (Zhangqiu) Co., Ltd. | All Rights Reserved 鲁ICP备12007127号 Technical support:Xintuweb
