Working with Centrifuges

1. General Protocol for Safe Centrifuge Usage

1. The laboratory supervisor or laboratory safety officer should ensure all users are properly trained in the selection of the rotor, sample tube, and proper operation of the centrifuge.
2. Any new user should be closely supervised by a trained user until he/she is confident on how to properly use the instrument.
3. Prior to using the instrument, each user should carefully read and understand the safety instructions for the specific centrifuge.
4. Depending on sample, compatible rotors should be used.
5. The rotor, tube, and spindle should be clean, dry, and free from cracks or deformities.
6. The O-rings should be checked for any wear or cracks.
7. It is important to make sure that the tubes used for centrifugation are compatible with the sample and the rotation speed (low, high, or ultra).
8. The centrifuge tubes should not be filled more than three-fourths of their maximum fill level.
9. The tubes should be capped tightly.
10. It is extremely important to balance the tubes opposite to each other. Failure to do so may lead to incomplete separation and, in extreme cases, can cause dispersion of the tube contents in the housing of the centrifuge.
11. Before turning on the centrifuge, the rotor should be checked to ensure it is correctly seated on the drive and the lid is properly closed.
12. The lid should be kept closed at all times when the centrifuge is in operation, and should never be open until the rotor completely stops.
13. The operator should remain in the vicinity of the centrifuge until it has safely reached the target operation speed. In the case of unusual sounds or vibrations, the instrument should be immediately turned off. The speed limit of the instrument should never be exceeded. Upon turning off, allow sufficient time for the rotor to slow down to a stopped position. Modern centrifuges have indicators that will signify that it is safe to open the centrifuge.
14. Once the centrifugation is over, samples should be removed and the instrument should be checked for any spills or leaks. If necessary, the rotor should be cleaned thoroughly.

2. Additional Precautions While Handling Hazardous Chemicals or Infectious Materials

1. When using hazardous chemicals or biological samples that might be infectious, it is important to label the instrument while in usage to alert other workers to the danger.
2. Appropriate gloves¹ should be worn to handle hazardous samples.
3. Sealed safety tubes should be used. It is preferable to use secondary confinement, if available, for the centrifuge tubes. These are usually in the form of plastic or glass inserts that are placed directly in the sample buckets of the centrifuge.
4. Once the centrifugation is over, the tubes should be removed from the rotor and opened only in the fume hood or biological safety cabinet, as applicable.
5. Cleaning, if required, should be done with extreme care, so as to not expose the operator to hazardous chemicals or infectious materials. In case of spills of such samples, see step 3, Emergency Situations, below.
6. For specific types of hazardous samples, it may be preferable to maintain standard procedures and cleaning protocols in laboratory. These should be reviewed and updated accordingly, as necessary.

3. Emergency Situations and Their Safety Measures

An emergency situation may arise if the rotor malfunctions or if there is a spill in the centrifuge due to tube breakage or mishandling. In such situations, the following steps should be taken.

1. The centrifuge should be turned off immediately and the lid should be kept closed until others are notified and evacuate the location. The power should be terminated at the power button on the instrument. The button will be located either on the front, side, or back of the instrument. The user should familiarize themselves with its location. If the power button is malfunctioning, then the user should remove the main power plug from the wall socket.
2. To reduce the risk of aerosols, it is sometimes better to leave the centrifuge untouched for at least 0.5 h. Consult with the centrifuge technical document.
3. For cleaning up spills, the operator should be well acquainted with the sample being used and should wear proper attire including lab-coat, gloves, facial shield, and safety glasses.
   1. Once cleaned, the spilled material should be properly disposed of and the contaminated protective clothing should be disposed of or cleaned properly. Hands and any exposed skin should be washed thoroughly.
4. If overtly exposed to highly hazardous materials, 911 should be called or immediate medical attention should be administered to the afflicted person.

4. Maintenance of the Centrifuge

NOTE: The body of the centrifuge is usually made from metals that can corrode in the presence of moisture, chemicals, or strong cleaning agents. For proper maintenance of the centrifuge, it is recommended to carefully follow the manufacturer's instructions for cleaning and maintenance. Other than that, a few general measures for maintenance to be kept in mind are as follows.

1. The centrifuge should always be kept clean and dry.
2. Any kind of spills should be immediately cleaned.
3. The rotor should be decontaminated after use with biological and radioactive materials. It is recommended to use 10% bleach for 30 min followed by 70% ethanol, letting the rotor air dry.
4. Abrasive brush wires should never be used to clean the rotor and associated parts.
5. The rotor should be inspected after each use by the operator and at least annually by manufacturer inspector.
6. A log book should be maintained for each centrifuge to keep a record of users, samples, and service history. Additionally, copies of any warranty-related materials can be included in this log book.