How to choose the right centrifuge

There are many types of centrifuges for experimentation, which are usually classified from the following aspects:

(1) According to the level of the speed can be divided into: low speed centrifuge,
high speed centrifuge and ultra high speed centrifuge;

(2) According to the requirements of temperature, it can be divided into: ordinary centrifuge and
temperature-controlled centrifuge ;

(3) According to the different rotors: horizontal rotor centrifuge and angular rotor centrifuge;

(4) According to the size of the centrifuge volume can also be divided into: floor-standing centrifuge,
desktop centrifuge , handheld centrifuge, etc.;

(5) According to the grade of the centrifuge, it can be divided into ordinary centrifuge and precision centrifuge.

Ordinary centrifuges do not have many functions, and are not accurate in terms of speed and capacity. For example, the maximum speed of a conventional centrifuge is 5000 rpm, but the actual speed cannot reach 5000 rpm. Such a centrifuge is only suitable for ordinary centrifugal work, such as: separation of blood test, serum separation, concentration of urine and other conventional experiments.

The precision centrifuge has many functions, accurate rotation speed and capacity, and is suitable for some experiments with high requirements on centrifuges, such as PCR experiments and separation of blood components (used in blood stations).

Choose a common centrifuge, depending on the size of the workload, mainly from the two aspects of speed and capacity. The following is a detailed description of the issues that should be noted when purchasing precision centrifuges:

(1) Rotating speed: The centrifuge is divided into low-speed centrifuges (30000 rpm/min) according to the maximum speed. Each centrifuge has a rated maximum speed. The maximum speed refers to the speed under no-load conditions, but the maximum speed. There are differences depending on the type of rotor and the size of the sample.

For example, the rated speed of a centrifuge is 16000 rpm/min, which means that the rotor rotates 16,000 times per minute at no load. After adding the sample, the speed will definitely be less than 16000 rpm/min. The rotor is different, the maximum speed is different (one imported centrifuge can be equipped with multiple rotors), the horizontal rotor can reach 15000rpm/min, but the angle rotor can reach 14000rpm/min. The specific difference should be consulted in detail. The relevant technical personnel of the production plant, so the choice of the speed should be cautious, the maximum speed of the selected centrifuge should be higher than the target speed. For example, the target speed is 16000 rpm/mIn, and the maximum speed of the selected centrifuge must be higher than 16000 rpm/min.

(2) Temperature: Some samples (such as proteins, cells, etc.) will be destroyed under high temperature conditions. This is to choose a refrigerated centrifuge. The refrigerated centrifuge has a rated temperature range. The heat generated by the centrifuge at high speed is balanced with the refrigeration system of the centrifuge at a certain temperature (the sample for general freeze centrifugation needs to be kept at 3 ° C ~ 8 ° C), and the specific amount can be related to the rotor, such as a centrifuge The rated temperature range is -10 °C ~ 60 °C, the horizontal rotor can be rotated to about 3 °C, if the angle rotor may only be about 7 °C. This should also be consulted in detail about the product sales personnel and the manufacturer. Technical staff.

(3) Capacity: How many sample tubes need to be centrifuged each time, how much capacity is needed for each sample tube, these factors determine the total capacity of a centrifuge, simply the total capacity of the centrifuge = the volume of each centrifuge tube The number, total capacity and workload size are matched.

(4) Rotor: The rotor of the centrifuge is mainly divided into two types: horizontal rotor: the running blue is in a horizontal state during operation, at right angles to the rotating shaft, and the sample concentrates the sediment on the bottom of the centrifuge tube: the angle rotor: the centrifugal container is fixed with the rotating shaft At the angle, the sample concentrates the sediment on the bottom of the centrifuge tube and the side wall near the bottom. 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 tests or special samples that require special rotors such as large-capacity baskets (used for blood stations), ELISA plate rotors, slide rotors, PCR rotors, test tube rotors, and capillary rotors. The rotor has a fixed size, which is combined with the capacity of the centrifuge, such as the 365ml angle rotor, which determines the type of rotor and the capacity of the centrifuge, so the choice of the rotor is very important.

(5) Control system: High-end centrifuges use microcomputer control systems. These control systems not only ensure the safe operation of the centrifuge but also automatically complete the task. Now many centrifuges have a better humanized control system.

For example: rotor identification function, safety lock function, fault prompt function, acceleration and deceleration curves, and so on. In addition to the above points, pay attention to some details and necessary accessories. The main component of the centrifuge is the motor. The motor is divided into a carbon brush motor and a carbonless brush motor. The former has been eliminated. Most of the current centrifuges are brushless motors, and some motors also have a brake function. Refrigerated centrifuges also differ in terms of 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 be equipped with 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.

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