8 Types of Laboratory Centrifuges & The Purposes They Serve

How Do Centrifuges Work?

One way centrifuges are used is to quicken natural, gravity-driven settling processes. This is achieved by using centrifugal force to rapidly separate the components. Without a centrifuge, particles would take hours or days to settle under normal gravity. As a result, centrifuge usage in lab settings can reduce the rate of delayed test results by 3.1%.

Other functions involve separating liquid mixtures that would not separate naturally, even after being left to sit for a long time, such as thick emulsions, blood, or oil products.

Here is how that process happens. 

1. Sample Preparation

The sample is placed into tubes. These tubes go into holders called rotors.

2. Balancing

The tubes must be balanced within the rotor to avoid uneven spinning. Technicians place tubes of equal volume opposite each other.

3. Spinning

Once the lid is closed, the motor spins the rotor at high speed. The speed is measured in revolutions per minute (RPM) or relative centrifugal force (RCF). As the rotor spins, centrifugal force acts on the particles inside the tubes.

4. Separation by Density

Particles with greater density move to the bottom or sides of the tube. Lighter particles remain near the top or mixed into the liquid. This happens because centrifugal force pushes heavier components outward.

5. Stopping & Collecting the Result

Once spinning stops, the components are clearly separated. The technician carefully removes the tubes and collects the needed sample. This could be either the particles themselves or the liquid free of the heavier particles.

Most types of centrifuges are also composed of the following parts. 

8 Different Types of Centrifuges & How They Are Used

1. Clinical Centrifuge

A clinical centrifuge is designed specifically for diagnostic laboratory use. It often features simple operation, moderate speed settings, and a rotor that accommodates blood collection tubes. Hospitals and diagnostic labs use clinical centrifuges for routine blood and urine analysis. Common applications include preparing serum or plasma from blood samples.

2. Hematocrit Centrifuge

Hematocrit centrifuges are specialized units designed to spin tubes filled with blood. Their primary purpose is to measure the hematocrit or red blood cell volume percentage. Clinical settings rely on hematocrit centrifuges to quickly produce accurate hematocrit values. This helps medical professionals diagnose conditions such as anemia or dehydration. 

3. Microcentrifuge/Mini Centrifuge

Microcentrifuges and mini centrifuges are compact units designed for small sample volumes. They typically use microcentrifuge tubes that hold 1.5 to 2.0 mL. Mini centrifuges are generally simpler and suited for quick spins or low-speed separations, while microcentrifuges can reach speeds up to 18,000 revolutions per minute (RPM).

Laboratories use these centrifuges for DNA and RNA extraction, protein analysis, and small-volume sample concentration. Their small size and rapid acceleration make them ideal for molecular biology projects.

4. Refurbished Centrifuge

A refurbished centrifuge is a pre-owned unit that has been restored to meet original equipment standards. Refurbishment typically includes inspection, replacement of worn parts, and performance testing to verify reliability.

Refurbished centrifuges are used in laboratories seeking to manage equipment costs while maintaining access to reliable, high-quality devices. They offer a cost-effective option for organizations with limited budgets or those needing backup equipment.

5. Benchtop Centrifuge

Benchtop centrifuges are versatile, compact units designed to fit on laboratory workbenches. They accommodate a wide range of tube sizes and sample volumes through various rotor options. Clinical, research, and industrial laboratories use these centrifuges for processing blood, urine, cell cultures, and other biological materials. 

6. Floor-Standing Centrifuge

Floor-standing centrifuges are large-scale units built to handle high-volume sample processing. They deliver greater force and offer large rotor capacities. Blood banks, pharmaceutical manufacturers, and industrial laboratories are most likely to use floor-standing centrifuges for large-batch sample separation. 

7. High-Speed Centrifuge

High-speed centrifuges operate at speeds between 15,000 and 30,000 RPM. They can separate organelles, bacteria, and cell debris from biological samples. These centrifuges serve cell biology and microbiology labs that need medium-to-high centrifugal force. They provide a useful option between standard benchtop models and ultracentrifuges.

8. Ultracentrifuge

An ultracentrifuge spins samples at very high maximum speeds, often exceeding 100,000 RPM. It generates strong centrifugal forces that can separate small particles, such as viruses, proteins, and nanoparticles, based on size and density. Ultracentrifuges are used in molecular biology, virology, and nanotechnology. Researchers rely on them to isolate subcellular components and to purify macromolecules with high precision.

6 Centrifugation Types & Which Centrifuges Suit Each One

1. Differential Centrifugation

Differential centrifugation separates particles based on size and density through repeated spins at increasing speeds. Larger, heavier particles sediment first while lighter components remain mixed in the liquid portion of a sample and can be further processed. Differential centrifugation is ideal for isolating organelles, cells, and macromolecules from complex mixtures.

Laboratories generally use ultracentrifuges, high-speed centrifuges, and benchtop centrifuges for this process.

2. Hematocrit Measurement

Hematocrit measurement involves centrifuging tubes of whole blood to separate blood cells from plasma. Hematocrit centrifuges are specifically designed for this process. They offer precise control and quick processing, making them standard equipment in clinical laboratories.

3. Pelletization

Pelletization uses high centrifugal force to drive particles to the bottom of the tube, forming a pellet. The remaining liquid portion can then be removed, and the pellet is resuspended or analyzed.

Microcentrifuges, mini centrifuges, benchtop centrifuges, and high-speed centrifuges all perform pelletization well, depending on the sample size. This process supports DNA extraction, protein purification, and cell harvesting.

4. Sedimentation Velocity Centrifugation

Sedimentation velocity centrifugation tracks how quickly particles move under centrifugal force. It provides information on particle size distribution and interactions. This process is used in pharmaceutical development and protein characterization studies.

Ultracentrifuges equipped with analytical rotors and optical detection systems are best for sedimentation velocity experiments. 

5. Clarification

Clarification removes suspended solids from liquids. The process does not aim for complete separation of all particle types but instead produces a clarified liquid suitable for further processing. Industries such as wastewater treatment, beverage production, and chemical processing use clarification extensively. High-capacity floor-standing centrifuges are best suited to clarification tasks.

6. Isopycnic Centrifugation

The goal of isopycnic centrifugation is complete separation by buoyant density, not by size or shape. A sample is layered over a gradient medium. During centrifugation, each particle migrates to the point where its density matches the surrounding gradient.

This method is used for purifying viruses, ribosomes, exosomes, and nucleic acids. Ultracentrifuges are the optimal choice for isopycnic centrifugation.

How Different Industries Use Various Centrifuge Types

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