With the development of molecular biology, genetic engineering research and application, centrifugal separation technology has also undergone several generations of replacement, from low-speed centrifuges, high-speed centrifuges, ultracentrifuges to ultra-high-speed refrigerated centrifuges, so that centrifugal separation technology has developed into a A new era. The existing analytical ultracentrifuge is also equipped with an analytical optical system that can be used for quantitative analysis. This article describes the common faults, troubleshooting methods and maintenance precautions of the centrifuge during clinical use.
In the process of use, the motor can not start normally. If the main power indicator light is on, the degree of wear of the carbon brush should be checked. If the carbon brush wear exceeds one third of the total amount, the new carbon brush should be replaced in time. When the main power indicator is off, check if the indicator fuse and the indoor distribution board fuse are blown. Also check whether the power line is in good contact. If the fuse is broken, replace the fuse and keep the circuit open. Also check the vacuum pump gauge and oil pressure indication value. If the oil pressure is too high and the main engine cannot start, it is necessary to check whether the oil passages are blocked, especially if the throttle orifice is unblocked. If it is not smooth, it should be cleaned to make it smooth. If the bearing is damaged or the rotation is blocked, there is a lack of oil in the bearing or there is more dirt in the bearing, which causes the frictional resistance to increase. If the motor does not reach the rated speed, the bearing should be cleaned or replaced in time. There is a layer of oxide on the surface of the commutator. Even if the bump is uneven or the brush does not match the outer edge of the commutator, the rotation speed can be lowered. The commutator and the brush should be cleaned to make the contact good. If the rotor coil is short-circuited or broken, use a multimeter to check and re-wind the coil. When the rotor is in use, the centrifuge tube may be broken, the sample leaks, and the rotor is damaged due to metal fatigue, overspeed, overstress, chemical corrosion, improper selection, unbalanced use of the rotor and temperature loss. For the above situation, the operator is required to be proficient in the operation procedure, correctly select the appropriate centrifuge tube and centrifugal rotor, pay attention to strictly control each step of operation, minimize unnecessary damage caused by human beings, and use it in the safety factor and warranty period of the rotor. .
The power failure is one of the causes of the start of the freezer and the poor cooling effect. The same as the failure of the motor, the power supply and fuse should be checked separately. If the voltage is too low, the safety device may also fail to start the freezer. If the voltage is too low, the voltage of the power grid may be low; the wiring of the power distribution board is too much; the ideal length of the power cable is 3 meters. The power line capacity is not enough, which not only reduces the voltage, but also causes accidents. When the power supply voltage drops to 180-190VJ, the freezer cannot be started, which affects the cooling effect. The ventilation performance is not good. If the instrument is installed in direct sunlight or poor ventilation, the radiator is not effective, or the radiator is covered with dust, which will affect the cooling effect. The weight of the centrifuge tube is unbalanced and placed asymmetrically; there is foreign matter in the rotor hole to make the load unbalanced; the fixed nut on the upper end of the shaft is loose, the shaft is rubbed or bent; the rotor of the motor does not generate noise in the center of the magnetic field; the damage of the rotor itself can cause the body The vibration is severe and the noise is abnormal. Most of the above reasons are caused by incorrect operation. After finding out the cause, correct operation can eliminate the abnormal phenomenon. In the course of work, if any abnormality occurs, it should be stopped immediately, and it must not be forced to run, so as to avoid unnecessary losses.
The following is a brief introduction to the maintenance and precautions of the centrifuge:
The installation of the centrifuge should be placed according to the performance of the centrifuge. For the general low-speed centrifuge table, it can be placed on a stable and sturdy table. Its base is equipped with rubber feet, with the help of atmospheric pressure and the instrument itself. Weight, close to the table; large-capacity low-speed centrifuges and high-speed centrifuges and high-speed refrigerated centrifuges 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 selecting a suitable rotor centrifuge, 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. The centrifuge bracket centrifuge separation bracket must be placed after the centrifuge tube is operated, and the empty frame operation is strictly prohibited. When the centrifuge is started, the speed switch or G value knob is placed in the low gear, and then gradually adjusted to the desired value after starting. After one work, turn the knob to the low gear to work again, and prohibit the direct start at high speed or G gear. The maximum rotational speed of the rotor is to reduce the maximum rotational speed of the rotor when the rotor is operated and the number of operations reaches a predetermined life. When the rotor is subjected to local surface damage or slight corrosion in the tube hole. When using stainless steel centrifuge tubes, bushings, thick wall tubes or centrifuge bottles. When the average density of the sample exceeds 1.2 g/cm3, the practical rotational speed N is:
Where N is the practical speed and N is the maximum speed.
When the rotor is exposed to high temperatures. The maintenance rotor of the rotor should be strictly checked for foreign matter and dirt in the hole before each use to maintain balance. The rotor must be kept dry and clean and must not be scratched. If you accidentally lose it, you should check the rotor for X-ray film and confirm that there is no internal damage. Centrifuge Tubes Centrifuge tubes can be made from a variety of different materials, such as polyethylene PE, cellulose CAB, polycarbonate PC, polypropylene PP, and the like. The tensile strength and elongation of various centrifuge tubes are different and should be selected as needed. Pay attention to ensure that the sample, solvent and gradient materials do not corrode the centrifuge tube and cap assembly. The centrifuge tube that has expired, aged, cracked or corroded is not used or slowed down to control the number of times the plastic centrifuge tube is used. Pay attention to the specifications. The centrifuge chamber cover has to be opened during centrifugation, and the rotating rotor and the centrifuge tube must not be hit by hand or foreign matter. The sample should be pre-cooled for 2000 r/min for a certain period of time. The pre-cooling control temperature is about 0 °C. The rotor can also be pre-cooled for several hours in the refrigerator. The centrifuge cup can be stored directly in the refrigerator. cold. Abnormal phenomena during centrifugation During the centrifugation process, if abnormal noise and vibration are found, the machine is immediately shut down for inspection. It is not allowed to continue operation until the cause is found. The host should be in a three-month maintenance period to correct the level of the host. For every 500 million revolutions of vacuum pump oil used, check the drive motor carbon brush for 500 hours. It is best to use a vacuum cleaner to remove the carbon powder generated by friction. If necessary, replace the carbon brush or light the commutator with fine sandpaper. The drive part bearing and four high-speed grease should be cleaned every 1500 hours or so. The joint between the shaft and the rotor 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 1-2 times a month at low speed, half an hour each time to ensure the normal operation of all parts. As mentioned above, there are many types of centrifugal rotors, and the shapes are different. It is troublesome to convert the centrifugal radius between each other. For this reason, the K-factor method of the centrifugal rotor is proposed, and the conversion between various centrifugal rotors is simplified.
The sink coefficient will be differentiated, S = dlnxl / w2t.
Usually centrifugal sedimentation from the minimum radius a to the maximum radius b,
Then S=Inb/a/W 2dt, let 1nb/a/W2=K, T=dt get S=K/T
From the above formula, the K value of each rotor at different rotational speeds can be calculated and listed as a K value table. If you need to change the centrifugal speed during the experiment, just find the K value of the corresponding speed, and then according to S=K/T, you can calculate the time that should be centrifuged after changing the speed.
For example, the K value of the original speed is K. The centrifugation time T1, now to use another speed of centrifugation, only need to find the corresponding K value from the table, such as K 2 because the sample sedimentation coefficient S is certain, so there is S = K1/T1 = K 2 / T 2 can calculate T 2 at K2. It can be seen from the above formula that the K value of the rotor of the same type reflects the centrifugal capacity of the rotor. The smaller the K value, the larger the centrifugal capacity, and the shorter the centrifugal time, the higher the rotor use value. . For more information, please visit
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