The reasons for the noise of the Roots oil pump and its start-up and shutdown

1、 The reason for the noise of the Roots oil pump

Whether it is the Roots oil pump or other equipment, it is rare that there is no sound during operation. So it is normal for everyone to hear some noise coming from inside when operating the equipment, but if the noise is too loud, it indicates that there must be an abnormality inside and needs to be repaired in a timely manner. So what is the reason for the noise on this device

1. Motor noise

Currently, the quality of motors varies. Motor noise often masks the noise of Roots oil pumps. Firstly, fan noise is generally high, and according to analysis, it should be caused by plastic fan deformation.

; The second is the bearing noise caused by the use of poor quality bearings

2. Internal component noise of Roots oil pump

1) rotor collision

It includes collision noise between rotor and rotor, rotor and pump body, and rotor and side cover.

. The main reasons for this are: insufficient stiffness of the shaft, radial displacement of the rotor and gear positioning on the shaft, excessive or insufficient gear clearance, and excessive axial clearance of the bearings

2) The gear of Roots oil pump

The factors that affect gear noise are not only the machining accuracy of the gear itself, but also the parallelism of the two rotor shafts where the gear is installed.

3) Bearings

In addition to the accuracy of the bearings themselves, inadequate design may also cause an increase in bearing noise, such as excessive interference in the installation of the inner and outer rings of the bearings, insufficient shaft stiffness, insufficient supply of lubricating oil, and contamination by dust, water, corrosive gases, and liquids.

So the noise emitted by the Roots oil pump during operation is basically caused by collisions, wear, and other internal components, and these components that are prone to making noise are also relatively easy to wear and tear. Therefore, when repairing and maintaining the equipment, these components must be maintained

2. Starting, Stopping, and Maintenance of Roots Pump

Roots Pump Installation

(1) It should be installed in a dry, well ventilated, and clean place.

(2) The ambient temperature of the Roots pump is 5-40 ℃

(3) Roots pumps should be installed horizontally with sufficient space around them for daily inspection and maintenance. Easy to assemble and disassemble

(4) After connecting the power supply, the motor rotation should comply with the rotation arrow on the pump

(5) The pipeline connecting the container to be pumped should be clean and free of impurities and other foreign objects. The aperture should not be smaller than the pump mouth diameter, and the length should be short to ensure sufficient conductivity. The pipeline connection should be sealed without leakage

Starting, stopping, and maintenance of Roots pump

(6) The extracted gas should have no granular solids entering the pump chamber.

(7) The connection between the Roots pump and the front stage pump should be equipped with an elastic tube to reduce the vibration caused by the front stage pump

(8) Electrical equipment has interlocking protection devices, and the Roots pump stops simultaneously when the current stage pump stops working

(9) Small pumps can be started directly, while large pumps require a starter

Instructions for using Roots pump:

After the new pump is in place, check the oil level first. The gear side oil level should be submerged in 3-5 teeth, and the motor side should be slightly higher than the center of the oil window. The oil cup on the shaft extension should not be short of oil, and the lubricating oil for all parts should use No. 1 vacuum pump oil.

1. Roots pump startup program:

(1) Start the pre stage pump.

(2) Open the pre extraction valve of the front stage pump and the valve on the inlet of the Roots pump

(3) After the pressure in the system reaches the allowable pressure of the Roots pump, close the pre extraction valve and start the Roots pump. If there is no pre extraction pipeline or valve, start the Roots pump after reaching the starting pressure. This process can also be automatically controlled by pressure sensors to achieve automation of the entire process

(4) According to the actual situation of the vacuum system, if it is not a large vacuum system, the Roots pump can be started after starting the front stage pump. If it is a large vacuum system, although the Roots pump with an overflow valve has overload protection, this protection is only for the motor. The Roots pump itself can still overheat and get stuck due to long-term operation under high pressure. It should be started after the front stage pump reaches a certain pressure

2. Roots pump shutdown program:

(1) Close the inlet valve of the Roots pump.

(2) Stop the Roots pump step by step from top to bottom, and then stop the previous stage pump. It is strictly prohibited to make mistakes in the shutdown procedure

(3) After the front stage pump stops, immediately release air from the inlet of the front stage pump

3. Precautions during the operation of Roots pump:

(1) Use according to the technical specifications of Roots pump during operation. Under normal circumstances, the inlet pressure of Roots pump is below 1330Pa, and the larger pressure difference of the pump should not exceed its larger allowable pressure difference.

(2) Pay attention to the load of the motor and the temperature rise of various parts of the pump. Under normal operation, the higher temperature rise of the pump should not exceed 40 ℃, and the higher temperature should not exceed 80 ℃. If a water ring pump is selected as the front stage pump, sometimes the temperature rise of the Roots pump may be increased due to the large ratio of pumping speed between the two pumps, but the higher temperature of the pump should not exceed 100 ℃

(3) There should be no irregular abnormal vibration or noise during operation

(4) If there is motor overload, high temperature rise, abnormal sound, or large vibration during operation, the machine should be stopped immediately to check the cause and eliminate the fault