A lab centrifuge is often a large investment. When shopping for a unit, you’ll be looking for something that meets all of your current needs as well as potential future needs.
The main factors to consider to ensure you make the right choice when selecting a lab centrifuge are:
- Maximum RPM and RCF
- Rotors available
- Temperature range
- Safety features
- Logistical factors
- Warranty options
In this post, we take a closer look at these factors and why they’re important.
1. Maximum RPM and RCF
How fast do you need your centrifuge to go? This might seem like a straightforward question, but bear in mind that RCF (relative centrifugal force) is more important than RPM (revolutions per minute) when discussing centrifuge speed. RCF (also known as G-Force) is the force being exerted on the contents of the rotor, and is the metric you should be most concerned about. RCF does depend on RPM (the rate at which the rotor is spinning), but it also depends on the radius of the rotor.
Most manufacturer specifications will tell you the maximum values for both RPM and RCF for a given unit.
The key attributes for the Z306 Universal Centrifuge show the maximum RPM and RCF for this unit.
2. Rotors Available
Each centrifuge model is compatible with a limited set of rotors and accessories, so you’ll need to look closely at what’s available. We go into detail about the process of deciding on a centrifuge rotor in a separate post, but here are the main things to consider:
- Compatibility with vessels: The centrifuge you choose needs to have rotor options that are compatible with your choice of vessel. For example, you’ll need to think about which tube shapes and sizes you will be using, or whether or not you’ll need to use PCR strips or microplates at some point.
- Rotor style: The main styles available are fixed-angle and swing-out rotors, and centrifuges may have options for one or the other or both. Other styles include vertical rotors, microlate rotors, and PCR strip rotors.
- RCF: As well as noting the maximum RCF of the centrifuge itself (as mentioned above), you also need to ensure your desired rotor will be able to handle your required RCF. Most rotors cannot operate at a centrifuge's maximum RCF, so you should be aware of the RPM/RCF limits of compatible rotors when considering your centrifuge. These are included in the manufacturer's specifications.
3. Temperature Range
Many centrifuges run at room temperature, with no cooling or heating options. However, there are refrigerated versions of some units that offer low temperatures, often down to -10°C or -20°C.
For example, the refrigerated version of the Z366 Series Universal Centrifuges has a temperature range of -20–40°C, as does the refrigerated Frontier FC5718 Multi-Pro Centrifuge. The Eppendorf Centrifuge 5424 R has a range of -10–40°C.
Left to right: A Z366 Series Universal Centrifuge, a Frontier FC5718 Multi-Pro Centrifuge, and an Eppendorf Centrifuge 5424 R.
Similar to RPM and RCF, not all rotors can achieve the same temperatures when using a refrigerated centrifuge. Some manufacturers will list the minimum achievable temperature for each rotor.
4. Safety Features
Centrifuges can pose multiple safety risks, but thankfully, many manufacturers build in safety features to help protect users and surrounding equipment. Here are some to look out for:
- Electronic lid-lock: To prevent the lid being opened accidentally while the centrifuge is running.
- Imbalance sensor: This senses when the centrifuge has not been balanced properly, and stops the centrifuge if a high level of vibration is detected.
- Sealed rotors: To prevent leakage of bio-hazardous substances during the centrifugal process.
- Rotor-recognition technology: This senses which rotor is installed and ensures that the rotor does not achieve a speed that surpasses the maximum speed it may be used at.
The NU-C200 General Purpose 2 Liter Centrifuge and the Eppendorf Centrifuge 5430 both come with rotor-recognition technology and an imbalance sensor.
5. Logistical Factors
When deciding on a centrifuge, it’s important to keep in mind logistical factors such as where the unit will be placed. All centrifuges produce some degree of vibration while running, so should be kept away from equipment that may be sensitive to this, such as lab balances.
There is also the concern that some units can be rather noisy, and could disrupt the lab environment, especially when running for long periods of time. Manufacturer specifications will often tell you what the approximate noise level (measured in decibels) will be when the centrifuge is running at max speed, so you can compare the level for various units.
For example, the approximate noise level at maximum speed for the Centrisart G-16 Benchtop Centrifuges is 57 dB.
6. Warranty Options
As mentioned, a lab centrifuge can be a big investment. As such, it’s wise to look ahead and scope out the warranty options offered by each manufacturer. For example, Benchmark Scientific offers a one or two-year warranty depending on the model, and Eppendorf, Ohaus, Sartorius, and Scilogex usually include two years in the purchase price. Hermle typically offers a five-year warranty, as does NuAire (within the US and Canada).