New Technologies and Safe Use of Medical Centrifuges

Introduction to New Technologies for Centrifuges

1.1 Temperature refrigeration

When the rotor rotates at high speed, air friction generates heat, causing the temperature of the rotor to rise, and the temperature of the sample in the test tube to also rise. Due to the sensitivity of biological samples to temperature. It is generally required to maintain a temperature of 4 ℃ in centrifugal experiments. Without intelligent technology controlled by computers, it is impossible to achieve an accuracy of ± 1 ℃. Therefore, a refrigerator is used to cool the centrifugal chamber, achieving the purpose of cooling the rotor and cooling the sample temperature. However, measuring the actual temperature of the rotating rotor is extremely difficult. Both domestically and internationally, temperature sensors are installed near the bottom of the centrifugal chamber to indirectly measure the rotor temperature. Here, T sample=T cavity+T compensation. T compensation is related to the type, speed, and operating time of the rotor.

1.2 Brushless motor direct drive

A centrifuge is driven by an electric motor with a rotor that rotates at high speed. The previous motor was a DC motor with carbon brushes. When the centrifuge was running, the carbon brushes were worn out, causing sparks, noise, and even vibration, and it had a lifespan. At that time, the carbon brushes needed to be replaced before running. More seriously, the wear of carbon brushes causes carbon dust pollution, which not only pollutes the centrifuge but also pollutes the surrounding environment. This type of pollution is not suitable for the health industry.

1.3 Display Digital Technology

The typical manifestation of simulation technology is to turn the knob to select operating parameters (such as speed, temperature, and time), and display data using the pointer on the dial. Its disadvantage is that the selection of parameters and the reading values of data are often subject to human interference from operators and readers, resulting in poor control accuracy. And every operation has to be done like this, with poor repeatability. Although some centrifuges have digital displays (such as knob selection and digital display) and have improved readings, the principle of value selection remains unchanged and still belongs to analog technology; The typical manifestation of digital display is full computer control with user-friendly interface, keyboard operation, digital display, and programmable operation. Its core is intelligent control, which is implemented by computers. All parameters required for centrifuge operation, such as speed, temperature, time, and speed range, are inputted through keyboard operation and displayed in numerical form. Therefore, the selection of operating parameters and the reading error are extremely small. Also, as it is a programmable operation, a set of operation parameters can be numbered and accessed for use.

How to safely use a centrifuge

2.1 Correct installation

(1) Power supply voltage: The voltage fluctuation must comply with the national standard within+10%, otherwise some manufacturers' centrifuges cannot operate normally. If the voltage fluctuates above this, it is recommended to use a voltage regulator to meet the requirements of this power grid.

(2) The grounding wire should be firm: the wiring of the power supply in the room should meet the requirements. Our country adopts a three-phase four wire system. Three phases are the three phases in industrial electricity. When using three-phase electricity, the neutral wire and ground wire are separated. More importantly, whether it is three-phase industrial electricity or general single-phase electricity, the ground wire should be reliable to avoid leakage. The ground wire should not be connected to heating pipes or water pipes.

(3) The ground should be flat and firm: For large centrifuges, when moving the floor at the installation site, it should be firm to ensure that the rotor of the centrifuge works normally and does not sink in. The ground at the installation and fixing point should be flat and firm.

(4) Find the right level: Find a more accurate small level, open the centrifuge cover, find the level on the spindle, and adjust the adjustment bolts next to the four casters to find the right level. Be careful not to let one foot fall empty.

2.2 Sample balancing

During the design and manufacturing of centrifuges, the imbalance caused by machining errors in the rotor has been remedied through dynamic balance tests. However, all centrifuges have their allowable sample imbalance. Centrifuge manufacturers strive to provide larger values in order to compete with other manufacturers on the maximum allowable unbalance limit of centrifuges. At this larger value, the centrifuge can operate, but the unbalanced force generated at this time suddenly impacts the bearings and brackets at a frequency of n times per minute, causing damage to the centrifuge. Therefore, for those expensive centrifuges, users should try to find a good balance and centrifuge them, which is beneficial for the lifespan of the centrifuges.

2.3 Cleaning the accumulated water in the centrifugal chamber

During the operation of the centrifuge, refrigeration is used. Due to the moisture in the air, frost forms in the centrifuge chamber, which turns into water after shutdown. Most low-speed and high-capacity centrifuges abroad do not have drainage holes, and the water in the centrifugal chamber accumulates more and more. At this point, the user should remove the rotor themselves and clean the accumulated water. When reinstalling the rotor, be sure to install it properly to avoid accidents.

2.4 Aluminum alloy cannot be corroded

Centrifuge rotors are generally made of aluminum alloy, and when corroded, their strength decreases, making them prone to accidents. Aluminum alloy is susceptible to liquid corrosion. After cleaning, it should be dried with a hair dryer or inverted for a period of time before use. Some imported centrifuges in blood stations do not have the 6 plastic trays that should be included in the 6 aluminum cups. A blood bag should be placed in the plastic tray to avoid placing it directly in an aluminum cup. Pay attention to any cracks in the test tube. If there are cracks in test tubes (especially those that are repeatedly used), they must not be used. Otherwise, if the test tube ruptures during use, it will cause the rotor to lose balance during rotation, which can lead to malignant accidents such as shaft breakage.

2.5 Axle breakage accident

The rotor is not properly placed or the sample is imbalanced by too much, causing the centrifuge to start. Although modern imported centrifuges have imbalance protection, when the imbalance exceeds a certain limit, the power should be automatically cut off, causing the centrifuge to stop running. But in the above situation, it is already too late and a serious accident may occur. One of the malignant accidents is shaft breakage. Due to sudden shaft breakage during high-speed rotation, the centrifugal rotor loses support and rotates and collides randomly in the centrifugal chamber, causing the entire centrifuge to rotate at a 270 ° angle. At this time, if there are people or equipment nearby, it can cause accidents such as casualties and damage to equipment.