This article is to introduce some main causes for roots pump noise during vacuum pump operation.
Roots vacuum pumps, also known as booster pumps, feature low noise as well as stable and high ultimate vacuum. However, unusual noise can be found during operation in some cases. The reasons could be:
1. Unlevel mounting surface
The Roots pump is requested to be mounted on a firm and level surface. Otherwise it will cause vibration of the pump and then bring noise.
2. Motor noise
The motor noise is usually caused by cooling fan, which is deformed after long time operation under high temperature. Another common reason is bearings of the motor: The quality of the bearings in use is not good enough or the bearings reach the end of the service life but that’s rare.
3. Friction and wear of internal components
The Roots pump noise is mostly the result of collisions and wears between its internal components during operation.
- Friction of the rotors
The noise is made by friction between rotors, or rotor and pump body, or rotor and side cover of the pump due to insufficient shaft stiffness, radial displacement of rotors and gears positioned on the shaft, improper gear clearance, or excessive axial clearance of the bearings.
The poor machining precision of the gears will cause noise. Moreover, it will also make noise if the parallelism of the two rotor shafts for gears has problem. Dry running of gears generates noise (lack of lubricant in the gearbox) as well.
There’re several different reasons from bearings which may cause Roots pump noise:
– Bearings with poor precision are used, or
– Incorrect bearings design, for instance excessive designed mounting overrun for the bearings, or
– Insufficient shaft stiffness, or
– Short supply of lubricant inside the bearings, or
– Unexpected exposure to water, dust, corrosive gases, or liquid, etc.
Briefly, the abnormal Roots pump noise during operation is mostly caused by frictions and wears between some inner components, which are also parts tended to make sound and easy to wear. For this reason, it’s recommended to check the status of the pump every 2-4 weeks, in particular check those spare parts during pump maintenance and repair.