Maintenance and troubleshooting of laboratory air compressor centrifuge
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Author : Runningway
Update time : 2019-11-02 09:57:49
There are many types of centrifuges. We are used to classify them from several aspects: according to the speed of rotation, we can divide them into: low-speed centrifuges, high-speed centrifuges and ultra-high-speed centrifuges; according to the requirements of temperature, they can be divided into: ordinary centrifuges and refrigerated centrifuges. According to the size of the centrifuge, it can be divided into: floor-standing centrifuge, desktop centrifuge, handheld centrifuge and so on.
Centrifuge composition
The ordinary centrifuge is made up of electric motor, turntable and governor. Casing, base, etc., in which the motor rotates at a light load, but the speed decreases sharply as the load increases.
1. Speed:
The centrifuge is divided into a low speed centrifuge (<10,000 rpm/min) and a high speed centrifuge (10,000 rpm/min---30,000 rpm/min) depending on the maximum speed.
2. Capacity:
How many sample tubes need to be centrifuged each time, how much capacity is required for each sample tube, these factors determine the total capacity of a centrifuge, simply the total capacity of the centrifuge = the capacity of each centrifuge tube × the number of centrifuge tubes, The total capacity and the size of the workload are matched.
3. Rotor:
Centrifuge rotors are mainly divided into two types:
Horizontal rotor: The basket is in a horizontal state during operation, at right angles to the shaft, the sample concentrates on the bottom of the centrifuge tube; the angle rotor: the centrifuge container is at a fixed angle to the shaft, and the sample concentrates the sediment on the bottom of the centrifuge tube and near the bottom. wall.
If you want the separated sample to be concentrated at the bottom of the centrifuge tube, select the horizontal rotor. If you want the sample to concentrate on the bottom of the centrifuge tube and the side wall near the bottom, select the angle rotor. There are also special experiments or special samples that require special rotors such as large-capacity baskets (used in blood stations), ELISA plate rotors, slide rotors, PCR rotors, test tube rack rotors and capillary rotors.
The rotor has a fixed size, which is combined with the capacity of the centrifuge. For example, a 12*5ml angle rotor determines the type of rotor and determines the capacity of the centrifuge, so the choice of the rotor is very important.
4. Control system:
High-end centrifuges use a microcomputer control system that not only ensures safe operation of the centrifuge but also automates tasks.
Many centrifuges now have better humanized control systems, such as rotor recognition, safety lock function, fault prompt function, acceleration and deceleration curves. The main components of the centrifuge are motors, which are divided into carbon brush motors and brushless motors.
The former has been eliminated, most of the current centrifuges are brushless motors, and some motors also have brake functions. Refrigerated centrifuges also differ in refrigeration, and now environmentally friendly technologies are of course fluorine-free refrigeration.
In addition to this, consider the noise problem and try to choose a quieter centrifuge to maintain a comfortable experimental environment. Care should be taken in the accessories. In some experiments, special centrifuge tubes (centrifugal toxic samples or samples requiring ultra-high-speed centrifugation) should be used. Such centrifuge tubes must have corresponding sleeves for safety. There are also some special sample containers (irregular vials, blood bags, etc.). These details and accessories must be carefully considered when selecting a centrifuge, otherwise normal operation will not be possible.
Centrifuge maintenance and use
(l) It must be placed on a stable, sturdy floor (countertop) before using the centrifuge.
(2) The chassis should be grounded when in use.
(3) The load must be balanced when used, and it must be placed symmetrically when the installation meets.
(4) When turning on the switch, the speed control knob should be in the “0” position.
(5) Turn on the switch speed control knob to open to the maximum, the correct way is to slowly increase the speed control knob.
(6) After use, the speed-regulating knob should be rotated back to “0”, and then let it stop. It is strictly forbidden to open the cover without being stopped and turned on.
(7) If the sound is not normal during use, it should be shut down immediately and checked and repaired.
(8) The wear of the commutator and the brush should be checked regularly (about one year). If there is excessive wear, it should be replaced immediately.
(9) The bearings of the motor should be filled with grease regularly.
5, the elimination of common centrifuge failure
(l) After power-on, the motor does not turn:
First check the power cord, plug, and socket. If there is any damage, replace it. If there is no problem, check whether the band switch or varistor is damaged or the cable is disconnected. If it is damaged or opened, replace the damaged component and re-weld the cable. The problem is to check whether the motor field coil is broken or open (internal). If the coil is broken, it can be re-welded. If the coil is internally broken, the coil can only be re-wound.
(2) The motor speed does not reach the rated speed:
First check the bearing. If the bearing is damaged, replace the bearing. If there is too much oil inside the bearing or too much dirt, the bearing should be cleaned and greased. Check whether the surface of the commutator is abnormal or whether the brush matches the surface of the commutator. If there is an abnormality on the surface of the commutator, if there is a layer of oxide, it will be sanded with fine sandpaper. If the commutator does not match the brush, it should be adjusted to a good contact. If there is no such problem, check the rotor coil for short circuit. If it is, rewind the coil.
(3) Vibrate and noisy:
Check for any unbalanced problems. Loose the nut of the fixed machine. If it is, tighten it. Check the bearing for damage or bending. If necessary, replace the bearing. The machine cover is deformed or the position is incorrect. If so, adjust it.
(4) The low speed gear cannot be started when it is cold:
The lubricant solidifies or the lubricant deteriorates and sticks. At the beginning, the hand can be used to help re-rotate or clean and then re-oil.
(5) The gap between the commutator and the brush is too large:
Check if the surface of the commutator is flat. If the surface is not flat, it can be sanded. If the problem is that the brush and the commutator are not in good contact, if the contact is bad, the surface will be polished with fine sandpaper, and the fit between the brush and the commutator will be re-adjusted. .
If the brush quality is unqualified, if the fault is the same, only the brush can be replaced. If there is no problem above, check whether the field coil has a partial short circuit or ground or the rotor coil has a partial short circuit or open circuit, such as the above situation, no matter which one appears. Rewind the field coil or rewind the rotor coil.
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