China Education Equipment Purchasing News: Centrifugation is to use the strong centrifugal force generated by the high-speed rotation of the centrifuge rotor to accelerate the sedimentation speed of particles in the liquid, and separate the materials with different sedimentation coefficients and buoyancy density in the sample. Therefore, it is necessary to use a centrifuge to generate a strong centrifugal force in order to force these particles to overcome the diffusion and generate a settling motion.
What failures will occur when we use a centrifuge? And how can we prevent failures?
1. The phenomenon that the motor cannot be started often occurs during use:
1. The main power indicator light is on. At this time, the degree of carbon brush wear should be checked. If the carbon brush wear exceeds one third of the total amount, a new carbon brush should be replaced in time.
2. When the main power indicator is off, check whether the indicator fuse and indoor distribution board fuse are blown, and check whether the power cord is in good contact. If the fuse is broken, replace the fuse and keep the circuit smooth.
3. The vacuum pump gauge and the oil pressure indication value should also be checked. If the oil pressure is too high and the host cannot be started, it must be checked whether the oil passages are blocked, especially whether the throttle orifice is unblocked. If it is unblocked, it should be cleaned to make it unblocked.
4. The bearing is damaged or the rotation is blocked. The lack of oil in the bearing or the dirt in the bearing causes the frictional resistance to increase. If the motor does not reach the rated speed, the bearing should be cleaned or replaced in time.
5. There is a layer of oxide on the surface of the commutator. Even if the sintered unevenness or the brush does not match the outer edge of the commutator, the speed can be reduced. The commutator and the brush should be cleaned to make good contact.
6. If there is a short circuit or open circuit in the rotor coil, you can check it with a multimeter and rewind the coil. When the rotor is in use, the centrifuge tube may rupture due to metal fatigue, overspeed, overstress, chemical corrosion, improper selection, unbalanced use of the rotating head, and temperature runaway. The sample may leak and the rotor may be damaged.
For the above situations, the operator is required to master the operation procedures, select the appropriate centrifuge tube and centrifuge rotor correctly, pay attention to strictly control each step of the operation sequence, minimize artificial unnecessary damage, and use it within the safety factor and warranty period of the rotor .
2. Power problem:
1. The power failure is one of the reasons leading to poor start-up of the refrigerator and poor cooling effect. It is the same as the failure of the motor not to turn, and the power supply and fuse should be checked separately.
2. If the voltage is too low, the safety device may also fail to start the refrigerator. If the voltage is too low, it may be that the grid voltage is low; the distribution board has too much wiring; the power cord is too long (ideal length is 3 meters). Insufficient power cord capacity not only reduces the voltage, but also causes accidents. When the power supply voltage drops to 180-190VJ, the refrigerator cannot start, which affects the cooling effect.
3. Poor ventilation performance, such as the instrument is installed in direct sunlight or poor ventilation, the radiator effect is poor, or the radiator cover is covered with dust, which will also affect the cooling effect.
4. The weight of the centrifuge tube is unbalanced and placed asymmetrically; there are foreign objects in the rotor hole, which makes the load unbalanced; the fixed nut on the upper end of the rotating shaft is loose, and the rotating shaft is rubbed or bent; the motor rotor is not in the center of the magnetic field, which can generate noise; It causes severe vibration and abnormal noise.
Most of the above reasons are caused by improper operation. After finding the cause, correct operation can eliminate abnormal phenomena. In the course of work, if there is any abnormal phenomenon, it should be stopped immediately, and it must not be forced to avoid unnecessary losses.
3. Maintenance and precautions of the centrifuge:
1. The installation of the centrifuge should be selected according to the performance of the centrifuge. The general low-speed centrifuge (desktop) can be placed on a stable and sturdy table (its base is equipped with rubber suction feet, with the help of atmospheric force Pressure and the weight of the instrument itself, close to the table);
2. Large-capacity low-speed centrifuges, high-speed centrifuges, and high-speed refrigerated centrifuges should be placed on solid ground accordingly and placed horizontally. Before choosing a suitable rotating head centrifuge, the load should be balanced, the smaller the weight error, the better, otherwise it will cause violent vibration and damage the centrifuge rotor and rotating shaft.
3. Centrifuge bracket The centrifuge separation bracket must be installed after operation of the centrifuge tube, and empty rack operation is strictly prohibited.
The following are several centrifuges:
SGZ800-1250 type three-foot scraper automatic unloading centrifuge
Three-legged centrifuge (speed 600-1200r / min) desktop centrifuge (mostly used in laboratory \ speed 0-3000r / min)
MINI200 desktop centrifuge
Disc Separator
(Xie Yinan / Editor)
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