1.1 Temperature cooling
When the rotor rotates at high speed, air friction generates heat, the rotor temperature will rise, and the sample temperature in the test tube will also rise. Because biological samples are sensitive to temperature. It is generally required to maintain the temperature in the centrifugal experiment at 4 ° C. Without computer-controlled intelligent technology, it is impossible to achieve an accuracy of ± 1 ℃. Therefore, the centrifugal chamber is cooled with a refrigerator to achieve the purpose of cooling the rotor and cooling the sample temperature. However, it is extremely difficult to measure the actual temperature of the rotating rotor. At home and abroad, a temperature sensor is installed near the rotor at the bottom of the centrifugal chamber to measure the rotor temperature indirectly. Here T sample = T cavity + T compensation. T compensation is related to the type, speed and running time of the rotor.
1.2 Direct drive of brushless motor
The centrifuge is rotated by a motor with a rotor at high speed. In the past, the motors were DC motors with carbon brushes. When the centrifuge was running, the carbon brushes were worn, causing sparks, noise, and even vibration, and had a life. At that time, the carbon brushes must be replaced to run again. Even more serious is the carbon dust pollution caused by the wear of carbon brushes, which not only pollutes the centrifuge, but also the surrounding environment. This pollution is not suitable for the health industry.
1.3 Display digital technology
The typical manifestation of the simulation technology is to turn the knob to select the operating parameters (such as speed, temperature and time, etc.), and display the data with the pointer of the dial. The disadvantages are: the reading values ​​of the selected parameters and data are subject to human interference between the operator and the reader, and the control accuracy is poor. And every time you do this, the repeatability is poor. Although some centrifuges have digital display (such as knob selection and digital display), although the readings have been improved, the value principle has not changed and it is still analog technology; the typical manifestation of digital display is friendly interface, keyboard operation, digital display , Programmable operation of full computer control, the core of which is intelligent control, is realized by a computer. All parameters required for operation of the centrifuge (such as speed, temperature, time, acceleration and deceleration rate, etc.), keyboard operation input, and displayed in numbers, so the selection of operating parameters and reading number error is very small. Because it is a programmable operation, a set of operating parameters can be programmed into numbers, which can be accessed and used.
2 How to use the centrifuge safely
2.1 Correct installation
(1) Power supply voltage: The voltage fluctuation must meet the national standard within + 10%, otherwise the centrifuges of some manufacturers cannot operate normally. If the voltage fluctuation is above this, it is recommended to use a voltage regulator to meet the grid.
(2) The ground wire should be firm: the wiring of the power supply of the room should meet the requirements. My country is a three-phase four-wire system. Three-phase is the three-phase of industrial power. When using three-phase power, the neutral line is separated from the ground line. What is more important is whether it is three-phase industrial power or general single-phase power. The ground wire should be reliable to avoid leakage. The ground wire cannot be connected to the heating pipe or water pipe.
(3) The ground should be flat and firm: For large centrifuges, the floor should be firm at the installation site to ensure that the rotor of the centrifuge works normally and does not sink into the ground. The ground at the fixed place should be flat and firm.
(4) Find a good level: find a small level that is more accurate, open the centrifuge lid, find the level on the main shaft, and find the level by adjusting the screw of the adjustment bolt beside the 4 casters. Note that one of the feet cannot be missed.
2.2 Find balance by loading samples
During the design and manufacture of the centrifuge, the unbalance caused by the processing error of the rotor has been remedied by the dynamic balance test. However, all centrifuges have their allowed unbalanced sample loading. In order to compete with other manufacturers on the index of the maximum unbalance limit allowed by the centrifuge, the centrifuge manufacturers try to give a larger value. At this larger value, the centrifuge can run, but the unbalanced force generated at this time suddenly hits the bearing and the bracket at a frequency of n times per minute, and the centrifuge is damaged. Therefore, users should try to find a good balance for those expensive centrifuges, which is good for the life of the centrifuge.
2.3 Clean up the water in the centrifugal cavity
Refrigeration is used when the centrifuge is running. Due to the moisture of the air, frost forms in the centrifuge chamber, and the frost turns into water after shutdown. Most low-speed large-capacity centrifuges abroad have no drain holes, and the more water accumulates in the centrifuge chamber. At this time, the user should remove the rotor and clean up the water. When reinstalling the rotor, it must be installed to avoid accidents.
2.4 Aluminum alloy cannot be corroded
The rotor of the centrifuge is generally made of aluminum alloy. When it is corroded, its strength decreases and it is easy to cause accidents. Aluminum alloys are susceptible to liquid corrosion. After cleaning, use a blower to dry them, or invert them for a period of time to confirm that they are dry before they can be used. Some blood stations import centrifuges, but the 6 plastic trays in the 6 aluminum cups are not. The blood bag should be placed in the plastic tray, and should not be placed directly in the aluminum cup. Note the test tube for cracks. If the test tube (especially the test tube used repeatedly) has cracks, it must not be used. Otherwise, the test tube rupture during use will cause the rotor to lose balance during rotation, which may cause malignant accidents such as broken shafts.
2.5 Shaft broken accident
If the rotor is not installed properly, or if the sample imbalance is too large, the centrifuge will start. Although modern imported centrifuges have unbalance protection, that is, when the unbalance amount exceeds a certain limit, the power should be automatically cut off to stop the centrifuge. However, under the above circumstances, it is already too late and there will be vicious accidents. One of the malignant accidents is shaft breakage. Because the shaft breaks suddenly during high-speed rotation, the centrifugal rotor has no support, and it rotates randomly in the centrifugal cavity, which can make the centrifuge rotate 270 °. At this time, if there are people or equipment next to them, it may cause casualties and damage the equipment.
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