Introduction to Medical Centrifuge Technology and User Guide

1. Temperature Control During Refrigeration: As the rotor spins at high speed, air friction generates heat, causing the rotor’s temperature to rise and, consequently, the temperature of the sample in the tube to increase as well. Since biological samples are highly sensitive to temperature, centrifugation experiments generally require that the temperature be maintained at 4°C. Without computer-controlled intelligent technology, it would be impossible to achieve a temperature accuracy of ±1°C. Therefore, a refrigeration unit is used to cool the centrifuge chamber, thereby cooling both the rotor and the sample. However, measuring the actual temperature of a rotating rotor is extremely challenging. Both domestically and internationally, temperature sensors are typically installed near the bottom of the centrifuge chamber, close to the rotor, to indirectly measure the rotor’s temperature. In this case, Tsample = Tchamber + Tcompensation. The Tcompensation value, in turn, depends on the rotor’s type, its rotational speed, and the duration of operation.

2. The brushless motor directly drives the centrifuge by rotating the rotor at high speed. In the past, motors were DC motors equipped with carbon brushes. During operation, these carbon brushes wore down, producing sparks, noise, and even vibration. Moreover, carbon brushes had a limited lifespan, requiring replacement to keep the machine running. Even more serious is that the wear of carbon brushes generated carbon dust, which not only contaminated the centrifuge itself but also polluted the surrounding environment. Such contamination is entirely unsuitable for the healthcare industry.

3. The liquid crystal display (LCD) technology typically features a user-friendly interface, keyboard-based operation, visual display, and fully computer-controlled programmable functions. At its core lies intelligent control, which is realized by the computer itself. All parameters required for centrifuge operation—such as rotational speed, temperature, time, acceleration/deceleration rates, and other settings—are entered via the keyboard and displayed on the LCD screen. As a result, selecting operational parameters and reading measurement data involve minimal errors, and the system supports programmable operations. A set of operational parameters can even be assigned numerical codes for easy storage and retrieval.

　II. User’s Guide for Medical Centrifuges
　
1. Correct installation
(1) Power supply voltage: Voltage fluctuations must comply with the national standard within a tolerance of ±10%. If voltage fluctuations exceed this range, it is recommended to use a voltage regulator to ensure compliance with the power grid.
　
(2) The grounding wire must be secure: The wiring of the room’s power supply must meet the required standards. In China, the power system uses a three-phase four-wire configuration. The three phases refer to the three-phase electricity used in industrial applications. When using three-phase power, the neutral wire and the ground wire must be kept separate. More importantly, whether it’s three-phase industrial power or ordinary single-phase power, the ground wire must be reliably connected to prevent electric leakage. Under no circumstances should the ground wire be connected to heating pipes or water pipes.
　　
(3) The floor must be level and stable: For large centrifuges, the floor at the installation site must be sturdy and well-secured to ensure that the centrifuge rotor operates smoothly without sinking or deforming. The floor at the installation and fixing locations should be both level and robust.

(4) Adjust the level: Find a small, relatively accurate spirit level. With the centrifuge lid open, locate the horizontal position on the spindle. Adjust the level by turning the adjusting bolts located next to the four casters. Be sure to pay attention to ensure that leg l does not become unsupported.

2. Load the sample and find balance.

　　When designing and manufacturing centrifuges, even though dynamic balancing tests are conducted to compensate for imbalances caused by machining errors in the rotor, every centrifuge has a permissible limit for sample loading imbalance. Many unscrupulous manufacturers, in order to compete with other suppliers on the maximum allowable imbalance level of their centrifuges, tend to specify higher values. While the machine can still operate at these higher imbalance levels, the resulting unbalanced forces will abruptly impact the bearings and support structures at a frequency of n times per minute, thereby causing damage to the centrifuge. Therefore, for users of expensive centrifuges, it is highly advisable to achieve optimal balance before starting the centrifugation process—this practice will significantly extend the lifespan of the centrifuge.
　
3. Remove any accumulated water from the centrifuge chamber. When the centrifuge is running, it uses refrigeration; as a result of moisture in the air, frost forms inside the centrifuge chamber. After the machine is turned off, this frost melts into water. Therefore, after using the centrifuge, open the door cover and allow any remaining frost to melt completely. Then, use a clean towel to wipe the interior clean.