Each system inside the centrifugal pump should be carefully maintained and repaired once a year. The suspicious part of the instrument should be calibrated and the internal dirt and dust should be removed. When it is not used for a long time, it should be regularly electrified to let the oil circulation and refrigeration system start up and run to ensure that the pipes are unblocked. The maintenance of each system is described below.
1. Maintenance of drive system
The driving system is the heart of the centrifuge. The abnormal phenomena of high-speed motor, variable speed gear, rotating bearing and sliding bearing will affect the normal operation of the instrument.
The main abnormal conditions of the drive system are: abnormal sound; burnt bearing, which has resistance feeling when rotating the rotor; broken dog gear, broken high-speed rotating shaft; slow speed rise, severe vibration, speed can not reach the rated speed; long-term operation of high-speed motor, dry bearing lubricating oil, resulting in abnormal sound vibration and speed instability due to thousands of abrasions.
In the long-term operation of high-speed motor, the wear of carbon brush is shortened, the pressure spring is loose, the adhesion of carbon brush is reduced, the resistance between carbon brush and commutator (commutator) is increased, and the pollution of carbon foam can form sparks. When the commutator is burned, it will emit a discharge "snap" sound, which will affect the normal operation of the electric machine. The short circuit, open circuit and insulation damage of the high-speed motor can make the motor hot and unable to start. In case of any of the above abnormal conditions, the machine shall be shut down immediately for maintenance.
2. Maintenance of vacuum system
At present, most ULTRACENTRIFUGES (high-speed centrifuges without vacuum system) adopt two-stage vacuum system of mechanical rotary vacuum pump and oil diffusion pump. The vacuum degree can reach 10-3mmhg, which greatly reduces the air friction resistance and the temperature rise caused by friction. In order to ensure the vacuum degree in the centrifugal cavity, the precooled rotor shall wipe the frost mist water on the surface before being installed on the rotating shaft, then enter the centrifugal chamber, and then start the vacuum pump to vacuumize.
In addition, during the long-term operation of the centrifuge, some water will be immersed in the ladle pump and mixed with oil. Therefore, in each maintenance, turn on the oil drain switch at the bottom of the vacuum pump, drain the water, then insert the accessory funnel into the ethylene pipe at the oil drain port, fill with mr-100 vacuum oil, and keep it up to the height of the oil level observation center mark. If the oil is found to be too dirty and black before drainage, just discharge and replace it all.
After the above maintenance, then check whether the ethylene pipe under the oil gathering tank is full of oil. In case of oil accumulation, the oil mould separator is blocked. In this way, screw off the top nut of the oil mist separator, remove the top cover and replace the extraction filter element
Whether the vacuum degree in the centrifugal cavity is good is not only related to the performance and failure of the vacuum pump itself, but also related to the sealing rubber ring of the instrument door, the shaft seal sleeve and the sealing of the pipeline. If any air leakage is found, it should be repaired immediately, especially for the parts and joints that are not paid much attention to.