Chemical laboratory centrifuge maintenance

The following introduces the maintenance and precautions of the centrifuge:

Centrifuge installation should be based on the performance of the centrifuge to choose the location of the co-operation, the general low-speed centrifuge (desktop) can be placed on a smooth, solid table (its base is equipped with rubber suction feet, with the help of atmospheric pressure and The weight of the instrument itself is closely attached to the table top; large-capacity low-speed centrifuges and high-speed centrifuges and high-speed refrigerated centrifuges should be placed on a solid ground and placed horizontally. The ultracentrifuge has a weight of several hundred kilograms and should be placed on a very solid ground with dustproof and moisture-proof equipment to ensure that the centrifugal chamber reaches a certain degree of vacuum and operates normally.

Before selecting the right rotary centrifuge, the load should be balanced. The smaller the weight error, the better. Otherwise it will cause severe vibration and damage the centrifugal rotor and shaft. Centrifuge bracket centrifuge separation bracket must be placed after the operation of the centrifuge tube, no empty rack operation. When the centrifuge is started, the speed switch or G value knob is placed in the low range, and then gradually adjusted to the required value after starting. After one work, turn the knob to the low gear again to work again, and disable the direct start at high speed or G block. The maximum rotational speed of the rotor is to reduce the maximum rotational speed of the rotor in the following cases. When the operating time and the number of operations of the rotor reach the specified life. When the rotor is damaged by a local surface or slightly corroded inside the hole. When using stainless steel centrifuge tubes, sleeves, thick-walled tubes or centrifuge bottles. When the average density of the sample exceeds 1.2g/cm3, the practical rotation speed N is: where N is the practical rotation speed and N is the maximum rotation speed. When the rotor is exposed to high temperatures.

Rotor Maintenance The rotor must be strictly inspected for foreign matter and dirt in each well before use to maintain balance. The rotor must be dry and clean. Do not bump it. If it is lost, check the rotor for X-rays to confirm that there is no internal damage. Centrifuge tubes Centrifuge tubes can be made from many different materials, such as polyethylene (PE), cellulose (CAB), polycarbonate (PC), polypropylene (PP), and the like. Various centrifugal tubes have different tensile strength and elongation and should be used as needed. Take care to ensure that the sample, solvent, and gradient material do not corrode the centrifuge tube and the lid assembly has expired, aged, cracked, or corroded. Centrifugal tubes do not use or decelerate as many times as necessary to control the number of uses of plastic centrifuge tubes. During the centrifugation, the cover of the centrifuge chamber had to be opened, and the rotating rotor and the centrifuge tube could not be hit by hand or foreign objects.

The cryogenic centrifugal sample should be precooled with an empty rotor for 2000 r/min for a certain period of time. When the precooling temperature is controlled at about 0°C, the rotor can be pre-cooled in the refrigerator for several hours. The centrifugal cup can be stored in the refrigerator directly. cold. Abnormal phenomena during centrifugation In the course of centrifugation, if abnormal noise and vibration are found, the machine is shut down and checked immediately. The operation cannot be continued until the cause is found. Host maintenance for three months to correct the level of a host computer. For every 500 million revolutions to be used for vacuum pumping, the carbon brush of the drive motor should be inspected for 500 hours. It is best to use a vacuum cleaner to remove the carbon powder from friction. If necessary, replace the carbon brush or light the commutator with fine sandpaper.

Every 1500 hours or so should be used to clean the bearings of the driving parts and the four high-speed greases. The joints between the shaft and the rotor should be greased and rusted. If they are not used for a long time, they should be coated with anti-rust oiled paper. When not in use at ordinary times, it should be switched on at a low speed every month 1 to 2 times, every half an hour, to ensure normal operation of all parts. As mentioned earlier, there are many kinds of centrifugal rotors, and their shapes are different. For the conversion of the centrifugal radii between them, it is troublesome. Therefore, the K factor method of centrifugal rotors is proposed to simplify the conversion between various centrifugal rotors.

Divide the coefficient of the sink, S=dlnxl/w2t. Usually centrifugal sedimentation from the minimum radius a to the maximum radius b, then S = In (b / a) / W2dt, set 1n (b / a) / W2 = K, T = dt S = K / T

From the above formula, the K value of each rotor at different rotation speeds can be calculated and listed as a K value table. If you need to change the centrifuge speed during the experiment, just find out the K value of the corresponding speed, and then according to S = K/T, you can calculate the time for centrifugation after changing the speed. If the original choice of speed into the K value of K. The centrifugation time T1, this time to use another speed centrifugation, only by the table to find the corresponding K value, such as K2 due to the sample's sedimentation coefficient S is a certain, so there S = K1/T1 = K2/T2 can Calculating T2 at K2, it can be seen from the above equation that the K value of the same kind of rotor reflects the centrifugal capacity of the rotor. The smaller the K value, the greater the centrifugal capacity, the shorter the centrifugal time, and the higher the rotor use value.