Common faults and treatment methods of vertical low-speed large-capacity refrigerated centrifuge
A centrifuge is a machine that uses centrifugal force to separate liquid and solid particles or components of a mixture of liquid and liquid. A centrifuge used in medicine is called a medical centrifuge. Medical centrifuges can be divided into low speed centrifuges (<10 000 r/min), high speed centrifuges (10 000~30 000 r/min) and ultracentrifuges (>30 000 r/min) according to the maximum speed. Refrigeration equipment can be divided into refrigerated centrifuges and general centrifuges. The failure phenomenon and maintenance method of the refrigerated centrifuge encountered in equipment maintenance for many years are summarized as an example of a low-speed refrigerating centrifuge. Example: The low-speed refrigerating centrifuge is a centrifugal experimental instrument with a maximum speed of 4000 r/min with refrigeration equipment. The main fault phenomenon is that the centrifuge does not rotate or the speed is not accurate, and the temperature control fails.
1. Fault one
1.1 Failure phenomenon The centrifuge does not turn and the speed does not reach the set value.
1.2 Analysis and maintenance of the centrifuge does not turn and the speed does not reach the set value for the following three reasons: (1) partial failure of the power circuit. First, repair the vulnerable parts such as the power cord, socket, plug, varistor (WH118, 3.3 kΩ, 2 W), relay (HH52P, HH53P). Then, check the circuit, air switch, rectifier, filter, transformer (OUT18V, 3 A) after the switching power supply, until the motor part. (2) The motor itself is faulty. The electric motor is one of the main components of the centrifuge, and the electric motor is divided into a carbon brush motor and a carbonless brush motor. The centrifuge is a carbon brush motor and most motors are now brushless motors. If the motor speed does not reach the set speed, first check the bearing, replace it when it needs to be replaced, and maintain it when maintenance is required (such as when adding lubricant and cleaning). Then, check if the motor commutator and the brush match, if the brush wears badly, and if it needs to be replaced. (3) The speed control part is faulty. The speed control system has an integrated chip (CW7815C III9501) to ensure safe and accurate operation of the centrifuge. If the speed is faulty, the chip or control panel can be replaced.
2. Fault two
2.1 Failure phenomenon The centrifuge temperature control fails, although it can be cooled but the temperature cannot be set.
2.2 Analysis and maintenance of the centrifuge temperature failure reasons There are two main reasons: (1) temperature control panel failure; (2) sensor failure. Temperature is an important parameter of the refrigerated centrifuge, because some samples (such as cells, proteins, etc.) will be destroyed in high temperature environment, and the centrifuge will generate energy under high speed operation, so the centrifugal system must be cooled by the refrigeration system. Keep the centrifugal environment within a certain range (such as 1 ~ 10 ° C). Open the cover and check the temperature control panel voltage. The 12 V and 6 V voltages are normal. Suspected that the temperature control chip (ICL7107CPL L9646) is abnormal, there is just a temperature control chip (ICL7107CPL 58840) removed from the scrapped old machine. After the replacement, the centrifuge is removed and the machine returns to normal. If the sensor failure causes the temperature measurement to be inaccurate and the erroneous data causes the refrigeration system to be switched on and off, the sensor wrapped in the periphery of the centrifuge body must be replaced.
3. Fault three
3.1 Failure phenomenon The centrifuge temperature setting is normal but cannot be cooled.
3.2 Analysis and maintenance analysis can set the temperature normally but there are two reasons for not cooling: (1) Excluding the temperature control panel failure, suspect the refrigeration system failure, because the user reflects that the centrifuge has poor cooling effect in recent days, after inspection, it was found Too little freon in the air compressor results in poor cooling. Fill the compressor with Freon and troubleshoot. (2) Sensor failure, fault 2 has been described, no longer rumored.
4. Centrifuge maintenance (1) Place the centrifuge on a solid ground before use, and the body should not be shaken to ensure that the peripherals such as the power supply are connected to the centrifuge without trouble. The sample must be balanced when it is loaded, because it will generate a lot of centrifugal force when the airborne operation, especially in high-speed operation, the unbalanced sample will generate a large torque, the light will cause the machine to shake or shake, and the heavy one will twist the shaft. Causes more jitter or even breaks. After turning on the power switch, set the speed, preferably from low speed to high speed. At this time, it is forbidden to open the cover. If you find an abnormality in use, you should turn off the power immediately. Do not wait for more serious consequences before turning it off. You should contact the medical equipment maintenance engineer in time. After the experiment is completed, gradually slow down until it stops itself and turn off the power.
(2) Medical equipment maintenance engineers should regularly replace the easily worn parts such as motor carbon brushes, fill the bearings with lubricating oil, check the components that are easily damaged by maintenance, and ensure that the working state of the machine is normal and prevent problems before they occur.
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