Precautions for Using an Electric Centrifuge

1. Correct installation

(1) Power supply voltage: Voltage fluctuations must comply with the national standard within ±10%; otherwise, centrifuges from certain manufacturers may fail to operate properly. If voltage fluctuations exceed this range, it is recommended to use a voltage regulator to ensure compliance with the power grid requirements.

(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 settings. When using three-phase electricity, 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 normally without sinking or deforming. The floor at the installation and fixing location 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 none of the four feet are unsupported.

2. Load the sample and find balance.

During the design and manufacturing of centrifuges, any imbalance caused by machining errors in the rotor is corrected through dynamic balancing tests. However, every centrifuge has a specified allowable level of sample loading imbalance. To compete with other manufacturers on the maximum allowable imbalance limit, centrifuge manufacturers tend to specify relatively high values. While the centrifuge can still operate at these higher imbalance levels, the resulting unbalanced forces will suddenly impact the bearings and support structures at a frequency of n times per minute, thereby causing damage to the centrifuge. Therefore, for expensive centrifuges, users are advised 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, refrigeration causes moisture in the air to condense into frost inside the centrifuge chamber. After the machine is turned off, this frost melts into water. Most low-speed, high-capacity centrifuges manufactured abroad are not equipped with drain holes, so water gradually accumulates in the centrifuge chamber. In such cases, users should remove the rotor themselves and clear out the accumulated water. When reinstalling the rotor, be sure to secure it properly to prevent accidents.

4. Aluminum alloys must not be subjected to corrosion.

Centrifuge rotors are typically made of aluminum alloy. Once corroded, their strength diminishes, making them prone to accidents. Aluminum alloys are susceptible to liquid corrosion; after cleaning, they should be dried thoroughly using a hairdryer or by turning them upside down for a while. Only after confirming that they’re completely dry should they be put into use. Some blood banks’ imported centrifuges lack the six plastic trays that should have been included in the six aluminum cups. The plastic trays are meant to hold blood bags, preventing direct contact between the bags and the aluminum cups. Also, be sure to check whether the test tubes have any cracks.

If a test tube—especially one that has been used repeatedly—shows any cracks, it must never be used. Otherwise, during use, the rupture of the test tube could cause an imbalance in the rotor’s rotation, potentially leading to serious accidents such as shaft breakage.

5. Shaft Breakage Accident

The rotor was not properly installed, or the sample loading was severely unbalanced. When the centrifuge is started, modern imported centrifuges are equipped with imbalance protection: if the imbalance exceeds a certain threshold, the machine will automatically cut off power and stop rotating. However, in the situation described above, it’s already too late—such conditions can lead to catastrophic accidents. One type of catastrophic accident is shaft failure. When the shaft suddenly breaks during high-speed rotation, the centrifuge rotor loses its support and starts spinning wildly, colliding randomly within the centrifuge chamber. This can cause the entire centrifuge unit to rotate by as much as 270 degrees. At this point, if there are personnel or equipment nearby, it could result in serious injuries or damage to both people and machinery.