1, centrifuge type
(1) General centrifuge
(2) High speed centrifuge
(3) Ultra high speed centrifuge
1 preparative ultracentrifuge
It mainly consists of four parts: drive and speed control, temperature control, vacuum system and rotor.
2 analytical ultracentrifuge
Analytical ultracentrifuges use specially designed rotors and inspection systems to continuously monitor the sedimentation of a material in a centrifugal field.
2, operating precautions
When the centrifuge is working, it is running at high speed. Pay attention to safety when using it. The following must be done:
(1) The centrifuge should be placed on a stable and sturdy table (the base is equipped with rubber suction feet, close to the table top by means of atmospheric pressure and the weight of the instrument itself); large-capacity low-speed centrifuge and high-speed The refrigerated centrifuge should be placed on a solid ground and placed horizontally. The ultracentrifuge weighs several hundred kilograms and should be placed on a very solid ground with dustproof and moisture-proof equipment to ensure that the centrifugal chamber reaches a certain degree of vacuum and normal operation. Before the centrifuge works, the load should be balanced. The smaller the weight error, the better. Otherwise, it will cause severe vibration and damage the centrifugal rotor and the shaft.
(2) The centrifuge separation bracket must be operated after the centrifuge tube is placed, and the empty frame operation is strictly prohibited. When the centrifuge is started, the speed switch or G value knob should be placed in the low gear position, and then gradually adjusted to the required value after starting. After one work, the knob must be adjusted to the low gear to work again, and the direct start is prohibited in the high speed gear or high G value.
(3) Select the appropriate rotor to control the speed of the rotor. The maximum speed of the rotor should be reduced in the following cases: when the running time and the number of running times of the rotor reach the specified life; when the rotor is damaged by local surface or slight corrosion occurs in the pipe hole; use stainless steel centrifuge tube, casing, For thick-walled tubes or centrifuge bottles; when the average density of the sample exceeds 1.2 g/cm3; when the rotor is subjected to high temperatures.
(4) Rotary head Before each use, it is necessary to strictly check whether there are foreign matter and dirt in the hole to maintain balance. The rotor must be kept dry and clean, and should not be bumped or scratched. If you accidentally fall, you should perform X-ray film inspection on the rotor to confirm that there is no internal damage before you can continue to use it. After each use, apply warm water (50 ° C ~ 60 ° C) and neutral detergent to soak, then rinse with distilled water or deionized water, dry with a soft cloth, dry with a hair dryer, wax, dry and preserve.
(5) The tensile strength and elongation of various centrifuge tubes are different, and should be selected as needed. The centrifuge tube can be made of many different materials, such as polyethylene, cellulose, polycarbonate, polypropylene, and the like. Care should be taken to ensure that the sample, solvent and gradient materials do not corrode the centrifuge tube and cap assembly. Centrifuge tubes that are out of date, aged, cracked, or corroded should be used as little as possible or at reduced speed. Control the number of times the plastic centrifuge tube is used, pay attention to the specifications. Do not open the centrifuge chamber cover during centrifugation. Do not hit the rotating head and centrifuge tube with your hands or foreign objects.
(6) For low-temperature centrifugation samples, the empty rotor should be pre-cooled at 2000 rpm for a certain period of time. When pre-cooling, the temperature is controlled at 0 °C. The rotor can also be pre-cooled for several hours in the refrigerator. The centrifuge cup can be used. Store directly in the refrigerator for pre-cooling.
(7) If abnormal phenomena are found during the centrifugation process, such as abnormal noise and vibration, stop the inspection immediately, and do not continue to operate until the cause is found.
(8) In the process of daily use of the centrifuge, the host should be calibrated once every three months. The vacuum pump oil should be used once every 500 million revolutions. The motor brush should be checked for 500h. It is best to use a vacuum cleaner to generate friction. The carbon powder is removed, if necessary, the carbon brush needs to be replaced or the commutator is polished with fine sandpaper. For every 1500h or so, the drive part bearing should be cleaned and high-speed grease should be added. The joint between the rotating shaft and the rotating head should be greased and rust-proof. If it is not used for a long time, it should be coated with anti-rust oil and oil paper. When not in use, it should be turned on at low speed every month for 1~2 times, 0.5h each time to ensure the normal operation of all parts.
3, the common failure of the centrifuge
(1) The decrease in vacuum is a common failure.
When the vacuum is lowered or the vacuum is not good, check the vacuum system. Generally, the oil is replaced and the vacuum is restored. In addition, small or desktop vacuum machines, people often forget to take the rotor placed in the centrifugal chamber, and the rotor will be stuck on the shaft for a long time. Can not be struck hard, this will damage the centrifugal shaft, causing the shaft to twist, which will damage the centrifuge and even accidents. If necessary, please ask a professional engineer to take it out.
For high-speed, ultracentrifuges, most of them do not have a vacuum device. The purpose is to make the centrifugal chamber in a medium or high vacuum state during operation, reducing friction on the rotor and making it stable. During the operation of the high-speed, ultra-high-speed centrifuge, there is a fault indication on the panel, and the fault can be handled for the corresponding fault prompt.
(2) The phenomenon that the centrifuge does not work.
For high-speed, ultra-speed centrifuges, see if the centrifugal conditions are properly selected, check the sensing part, control system and display unit, etc., and check the steps to find out the cause. For small or desktop centrifuges, people often forget to keep the rotor in the centrifuge chamber. After a long time, the rotor will be stuck on the shaft. In order to remove the rotor, it must be struck hard, which will seriously damage the centrifugal shaft. , causing the shaft to twist, can not recover, and even damage the centrifuge.
Proper operation and reasonable maintenance are the key to ensure the normal operation of the instrument and extend the service life of the instrument. Centrifuges with superior performance must be routinely maintained to maximize the efficiency of the centrifuge.
4, centrifuge maintenance and maintenance
(1) When ultracentrifugation, care should be taken to select a suitable centrifuge tube and rotor. When the rotation speed exceeds 25% of the maximum speed of the rotor used, the rotor will explode. Before using the rotor, it should be pre-cooled in the refrigerator. After centrifugation, the rotor should be washed with warm water and dried. The better way is to dry the rotor. The rotor should not be coated with glazing wax for a long time.
(2) The bearings of the motor are regularly greased, and the over-weared gasket is replaced immediately. Prevent the seal from aging and check for deformation as time goes by. A rubber sealing ring is arranged at the upper part of the inner cavity of the centrifuge and the door. When the use time is extended, the deformation should be observed frequently to prevent the external heat from infiltrating, so that the cooling effect is poor and the detection result is affected.
(3) The centrifuge tube used must ensure quality, poor quality, and the centrifuge tube that has been deformed or cracked cannot be used. Keep the centrifuge tube symmetrically balanced, and pay attention to its cleaning, disinfection and maintenance. Keep the centrifuge cup symmetrically balanced.
(4) Do a good job of the centrifuge fault record, such as the cause of the fault and the method and time of the instrument.
(5) Pay attention to the maintenance of the rotor. If there is corrosive gas in use or in a humid environment, it will seriously affect the life of the centrifuge rotor. Therefore, it is strictly forbidden to use the damaged centrifuge tube, or the centrifuge tube is overfilled or the seal is not tight and leaks during work.
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