The drive system is the core part of a benchtop centrifuge. Any abnormality in the high-speed motor, gearbox, rotating bearings, or sliding bearings will affect the normal operation of the instrument. The main abnormalities in the drive system of a benchtop centrifuge include: abnormal noise; burnt bearings; and interruption of the high-speed rotating shaft. Slow acceleration, violent oscillation, and failure to reach the rated speed; prolonged high-speed operation of the motor can cause the bearing lubricant to dry out, resulting in abnormal noise and vibration, and unstable speed.
When a benchtop centrifuge operates at high speed for a long time, the carbon brushes wear down, the pressure springs loosen, the adhesion of the carbon brushes decreases, the resistance between the carbon brushes and the commutator increases, and carbon dust contamination occurs, all of which can cause sparking. Burning of the commutator will also produce a "clicking" discharge sound, affecting the normal operation of the motor. Short circuits, open circuits, and insulation damage in the high-speed motor will cause the motor to overheat and fail to start.
If any of the above abnormalities occur, the benchtop centrifuge should be stopped immediately for repair.
Routine maintenance of benchtop centrifuges in the laboratory mainly involves preventing contamination of the centrifuge chamber by dust and oil. Before and after each experiment, clean the grease, water vapor, sample leakage, and workbench surface inside the centrifuge chamber with a clean white cloth. When not in use, do not open the door unnecessarily to prevent contamination. The sealing ring of the benchtop centrifuge should ensure good sealing; after a period of use, apply vacuum sealing grease. If the sealing ring is found to be aging, cracked, or losing elasticity, it should be replaced immediately. The switches, knobs, and fault indicators on the control panel should ensure good contact. If any abnormalities or malfunctions are found during operation, stop the machine immediately for repair.
Secondly, all systems inside the benchtop centrifuge should be carefully maintained and inspected annually. The suspicious parts of the benchtop centrifuge should be inspected, and dirt and dust should be cleaned from the documentation section. When not in use for extended periods, the centrifuge should be powered on periodically to activate the oil circulation cooling system and ensure the pipelines remain clear.
Additionally, during prolonged operation, some water may enter the oil pump of the benchtop centrifuge and mix with the oil. Therefore, during each maintenance check, the oil drain valve at the bottom of the vacuum pump should be opened to drain the water. Then, an accessory funnel should be inserted into the ethylene tube at the drain port, and vacuum oil should be added until the oil level reaches the marked height on the oil level indicator. If the oil is found to be too dirty or dark before draining, it should be drained and replaced.
After performing the above maintenance on the benchtop centrifuge, check if the ethylene tube under the oil sump is full of oil. If oil accumulation is found, it indicates that the oil mist separator is blocked. The top screw of the oil mist separator needs to be unscrewed, the top cover removed, the filter element taken out, and the vacuum level in the centrifuge chamber checked. The vacuum level is not only related to the function and malfunction of the vacuum pump itself, but also to the sealing of the instrument door's sealing ring, shaft seal, and pipelines. If water leakage is found in the benchtop centrifuge, especially in inconspicuous areas and connections, it should be repaired immediately.