Choosing a compact centrifuge: a guide for laboratories

A laboratory centrifuge does not need to be large to be powerful. A compact centrifuge combines high capacity with a small footprint, therefore saving you valuable bench space. However, the choice is not always straightforward. Therefore, the right choice depends on speed, rotor type, cooling and application. In this article we outline the most important factors, with practical input from Robert van der Kuijlen, director of Poly Temp Scientific. Additionally, explore our full range of laboratory centrifuge for a broader overview.

What is a compact centrifuge?

A compact centrifuge is a benchtop or small floor-standing unit that separates samples using centrifugal force. Therefore, a rotor spins at high speed, pushing heavier particles to the bottom of the tube. Moreover, a compact model delivers this performance without occupying an entire workbench. As a result, this type of centrifuge is popular in clinical labs, research settings and pharmaceutical development.

A compact centrifuge processes a wide range of tube formats. Additionally, the unit supports blood tubes, conical tubes, microtubes, PCR strips and microplates. Therefore, a single unit remains usable for many different protocols.

RCF versus RPM: what do the numbers mean?

When choosing a centrifuge, you encounter two terms. Therefore, it is important to understand the difference.

• RPM (rotations per minute) indicates how many rotations the rotor makes per minute. However, this says nothing about the actual force on the sample.
• RCF (relative centrifugal force) is the actual separation force, expressed in times gravity (x g). Therefore, RCF is the value that matters when reproducing a protocol.

The RCF depends on both the speed and the radius of the rotor. Moreover, the same RPM can produce a higher RCF in a larger rotor. Therefore, always work with the RCF value from your protocol, not the RPM.

Swing-out versus fixed-angle rotor

The rotor type largely determines what you can use the centrifuge for. Additionally, it influences the maximum speed and the type of separation.

Swing-out rotor (swinging bucket)

In a swing-out rotor, the tube holders swing outward during spinning. Therefore, the pellet forms neatly at the bottom of the tube. This type is ideal for blood separation, urinalysis and larger volumes. For example, a swing-out rotor processes up to 24 blood tubes of 5/7 mL per run.

Fixed-angle rotor

A fixed-angle rotor holds the tubes at a fixed angle. Therefore, this type reaches much higher speeds and RCF values. Moreover, a fixed-angle rotor is suitable for microtubes, DNA and protein preparations and fast spins beyond 30,000 x g. Therefore, research labs often choose this type.

Ventilated or refrigerated: do you need cooling?

Temperature-sensitive samples require cooling. Therefore, the distinction between ventilated and refrigerated models is important.

• Ventilated centrifuge: dissipates heat with a fan but does not actively cool. Therefore, this suffices for routine separations at room temperature.
• Refrigerated centrifuge: keeps the sample at a set temperature, typically between -10 °C and 40 °C. Therefore, this type is essential for cells, enzymes and other temperature-sensitive samples.

Modern refrigerated models increasingly use a natural refrigerant. Additionally, this significantly lowers the environmental impact, which we explain below.

The Thermo Scientific C Series as a compact solution

A good example of a modern compact centrifuge is the Thermo Scientific C Series. Furthermore, this series is designed for clinical and research applications and offers high capacity in a compact design. Moreover, the series consists of three models, therefore providing a suitable variant for nearly every lab.

Three models: C1T, C1TR and C1FR

The C1T is the ventilated base variant for routine work at room temperature. Additionally, the C1TR offers active cooling in a benchtop format. The C1FR is the refrigerated floor model for labs seeking even more capacity. Therefore, the series scales with the needs of your lab.

Sustainable cooling with GreenCool and R290

The refrigerated models (C1TR and C1FR) use GreenCool Technology, a cooling system based on the natural refrigerant R290. Therefore, the Global Warming Potential (GWP) is only 3, compared to 1,430 for the widely used R134a. Moreover, these models consume up to 15.7% less energy than their predecessors. Therefore, they suit labs with sustainability goals.

Many labs underestimate how much bench space a centrifuge takes up. With the C Series, the user gets surprisingly high capacity in a small unit. Moreover, thanks to the Auto-Lock rotor exchange, the user switches between applications within seconds, without tools. In practice, that saves a great deal of time.

— Robert van der Kuijlen, director Poly Temp Scientific

Applications in the clinical and research lab

A compact centrifuge is broadly applicable. Additionally, the chosen rotor determines the exact application. In the clinical lab, this often involves blood and urine separation.

• Platelet-poor plasma (PPP): with the right fixed-angle rotor, separation is possible in approximately one minute.
• Urinalysis: separation of sediment for microscopic examination.
• Blood chemistry: serum separation for analysis of potassium and liver values, among others.

In the research lab, the focus is instead on cell biology, molecular biology and protein work. Therefore, the flexibility of the rotor range is decisive here. For applications in pharma and biotech, also see our page on the pharmaceutical industry and biotech.

Which compact centrifuge suits your laboratory?

The choice depends on your samples, volumes and applications. Therefore, the selection help below points you in the right direction.

Choose a ventilated model (C1T) if:

• Your samples do not require cooling.
• You mainly perform routine separations at room temperature.
• You are looking for a competitively priced, compact solution.

Choose a refrigerated model (C1TR or C1FR) if:

• You work with temperature-sensitive samples such as cells or enzymes.
• Sustainability and low energy consumption factor into your choice.
• You need a floor model with extra capacity (C1FR).

Unsure which compact centrifuge best suits your situation? Our specialists are happy to advise you on rotor choice, cooling and capacity. Get in touch for personal advice or request a quote for your preferred model.