How to choose a centrifuge

How to choose a centrifuge

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

(1) According to the rotation speed, it can be divided into: low-speed centrifuge, high-speed centrifuge and ultra-high-speed centrifuge;

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

(3) According to the different rotors, it is divided into: horizontal rotor centrifuge and angle rotor centrifuge;

(4) According to the size of the centrifuge, it can also be divided into: floor centrifuge, desktop centrifuge, palm centrifuge, etc.;

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

Ordinary centrifuges do not have many functions and are not precise in terms of speed and capacity. For example, the maximum speed of an ordinary centrifuge is 5000 rpm, but the actual speed cannot reach 5000 rpm. Such centrifuges are only suitable for ordinary centrifugal work, such as: separating serum, concentrating urine, etc.

The precision centrifuge has multiple functions, accurate speed and capacity, and is suitable for experiments that require high centrifuges, such as PCR experiments, blood component separation (mostly used in blood stations), etc.

Purchasing ordinary centrifuges, according to the size of the workload, mainly choose from two aspects of speed and capacity. The following is a detailed introduction to the issues that should be paid attention to when choosing a precision centrifuge:

(1) Rotation speed: centrifuges are divided into low-speed centrifuges (30000 rpm) according to the maximum speed. /Min), each centrifuge has a rated maximum speed. The maximum speed refers to the speed under no-load conditions, but the maximum speed varies according to the type of rotor and the size of the sample.

For example: the rated speed of a centrifuge is 16000 rpm/min, indicating that the rotor rotates 16000 times per minute when there is no load. After adding the sample, the speed will definitely be less than 16000 rpm/min. The maximum speed is different depending on the rotor (an imported centrifuge can be equipped with multiple rotors). The horizontal rotor can reach 15000 rpm/min, but the angle rotor can reach 14000 rpm/min. Please consult the product for specific differences. Sales personnel and relevant technical personnel in the production plant should be cautious in the choice of speed. The maximum speed of the selected centrifuge should be higher than the target speed. For example: the target speed is 16000 rpm/min, 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 in a high temperature environment. This requires a refrigerated centrifuge, which has a rated temperature range. When the centrifuge is running at high speed, the heat generated by the centrifuge is balanced with the refrigeration system of the centrifuge at a certain temperature (generally, samples for refrigerated centrifugation need to be kept at 3°C to 8°C). How much can be achieved is also related to the rotor, such as a centrifuge The rated temperature range is -10℃～60℃, and it can reach about 3℃ when rotating with a horizontal rotor. If it is an angle rotor, it may only reach about 7℃. In this regard, we must consult product sales personnel and related technical personnel in the production plant in detail.

(3) Capacity: How many sample tubes need to be centrifuged each time, and how much capacity each sample tube needs. These factors determine the total capacity of a centrifuge. Simply put, the total capacity of the centrifuge = the capacity of each centrifuge tube × centrifugation The number of tubes, the total capacity and the workload are matched.

(4) Rotor: There are two main types of rotors in the centrifuge. Horizontal rotor: The hanging basket is in a horizontal state during operation and is at right angles to the shaft. The sample concentrates the sediment at the bottom of the centrifuge tube: Angle rotor: the centrifuge container and the shaft are fixed together. 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 samples to concentrate on the bottom of the centrifuge tube, choose a horizontal rotor. If you want the sample to concentrate on the bottom of the centrifuge tube and on the side wall near the bottom, you should choose an angular rotor.

There are also some special tests or special samples that require special rotors such as: large-capacity hanging baskets (mostly used in blood stations), enzyme plate rotors, slide rotors, PCR rotors, test tube rack rotors, capillary rotors, etc. The rotor has a fixed specification, which is combined with the capacity of the centrifuge, such as a 36×5 ml angle rotor, which determines the type of the rotor and the capacity of the centrifuge, so the choice of the rotor is very important.

(5) Control system: All high-end centrifuges adopt microcomputer control systems, which can not only ensure the safe operation of the centrifuge but also complete the tasks automatically. Many centrifuges now have better humanized control systems.

For example: rotor identification function, safety lock function, fault prompt function, acceleration and deceleration curve and so on. In addition to the above points, we must pay attention to some details and necessary accessories. The main component of the centrifuge is the motor. The motor is divided into a brush motor and a brushless motor. The former has been eliminated. Most of the centrifuges now are brushless motors, and some motors also have a brake function. Refrigerated centrifuges are also different in terms of refrigeration. The current environmentally friendly technology is of course CFC-free refrigeration. In addition, we must also consider noise issues, try to choose a low-noise centrifuge, so as to maintain a comfortable experimental environment. Be cautious in terms of accessories. Some experiments need to use special centrifuge tubes (centrifuge toxic samples or samples that require ultra-high-speed centrifugation). Such centrifuge tubes must be equipped with corresponding tube sleeves to be safer. There are also some special sample containers (irregular sample bottles, blood bags, etc.). These details and accessories must be carefully considered when choosing a centrifuge, otherwise normal work cannot be performed.