1、 Select according to the required centrifugal force:
Centrifuge is the use of centrifugal sedimentation principle, so that the density of cells (particles) in the solution are separated, concentrated or purified. The centrifugal tube with the same amount of test solution is placed symmetrically in the rotor (test tube). After the instrument is started, the relative centrifugal force (RCF) generated by the high-speed rotation of the rotor driven by the motor separates the cells (particles) with different densities in the test solution. The relative centrifugal force depends on the horizontal distance between the sample position and the axis, i.e. the rotation radius R and the rotational speed n.
The calculation formula is as follows:
RCF＝1.118×10-6n2r×g
Speed (RPM)
R -------- radius of rotation (mm)
2、 According to the separation workload and research needs, the selection was made
1. In general, desktop centrifuges are often used in research and small batch preparation;
2. Large scale floor type centrifuges are often used for mass preparation;
3. The laboratories of grade 2 A and above at county level are mostly equipped with refrigeration system, desktop high-speed freezing centrifuge or floor type low-speed freezing centrifuge, and township medical units mostly use desktop high-speed freezing centrifuge;
4. Medical units with large blood bank should choose blood centrifuge.
3、 Select according to the required temperature of the sample:
1. The separated sample can be stored at room temperature + 15 without changing its characteristics, so the normal temperature centrifuge can be selected.
2. If the separation of samples will be affected by temperature and its characteristics will be changed (such as protein, cells, etc.) will be destroyed in high temperature environment, so we should choose the frozen centrifuge, which has a rated temperature range.
3. Some samples need to be heated (such as oil, milk fat) according to the test requirements, heating centrifuge should be selected.
4、 Select by brand:
(1) Pay attention to the place of origin: the main production and distribution centers of domestic centrifuges are Beijing, Changsha, Anhui, Shanghai and other places, especially Changsha, Hunan.
  (2) pay attention to brands: there will also be many manufacturers of different brands in the main production distribution centers, and many manufacturers are keen to display their virtual strength by hanging certificates, continuing the glory of the old state-owned factories, double high-tech personnel, etc.
(3) Pay attention to modeling: many manufacturers are actually small assembly plants with three or five shareholders. They have neither R & D capability nor control technology, and their own strength is insufficient. They use public molds to follow a homogenized production line, resulting in the same shell shape of products on the market.
However, some powerful private enterprises have already caught up and developed a series of new generation products with different shapes and high technology content with their own strength. For example: the 3H series intelligent high-speed freezing centrifuge of Herexi instruments, the HR / t16mm micro high-speed freezing centrifuge of Guangzhou Xiangyi Centrifuge.
The choice of turning head
Rotor: the rotor of centrifuge is mainly divided into two types.
Horizontal rotor: during operation, the hanging basket is in a horizontal state and at right angles to the rotating shaft. The sample will concentrate the sediment at the bottom of the centrifugal tube.
Angle rotor: the centrifugal container is at a fixed angle with the rotating shaft, and the sample concentrates the sediment at the bottom of the centrifugal tube and the side wall near the bottom. The horizontal rotor is selected if the separated sample is concentrated at the bottom of the centrifugal tube, and the angular rotor is selected if the sample is to be concentrated at the bottom of the centrifugal tube and on the side wall near the bottom.
Some special tests or samples need special rotors, such as large capacity basket, enzyme plate rotor, slide rotor, PCR rotor, tube rack rotor and capillary rotor. The rotor has a fixed specification, which is combined with the capacity of the centrifuge. For example, the angle rotor of 36 × 5 ml determines both the type of rotor and the capacity of centrifuge, so the selection of rotor is very important.