How to Choose a Lab Centrifuge: A Selection Guide for Clinical Labs

Choosing a centrifuge for the clinical laboratory is about more than just comparing settings and tube capacity. The right centrifuge needs to match the tubes your lab uses, the sample types you spin, and the RCF and cycle times your workflows require.

Clinical centrifugation requirements vary depending on your lab’s applications. Serum separation, platelet-poor plasma preparation, blood bank serology, and urine sediment examination each require different processing conditions. These differences affect which rotor configuration, relative centrifugal force (RCF), and cycle settings are needed.

Maximum RPM and tube capacity are both useful specifications to consider, but they don’t establish whether a centrifuge is appropriate for a particular application. Collection tube compatibility, RCF, and cycle duration should all be evaluated alongside specimen volume and laboratory workload to make sure a centrifuge meets your processing needs.

What Centrifuge Does a Clinical Lab Need?

A clinical centrifuge separates sample components and concentrates cellular material for examination. They can be used for a range of applications, including serum, plasma, blood bank serology, and urine sediment examination. Each application has its own processing requirements, which means there is no single set of specifications that will work for every laboratory.

Serum and Plasma Preparation

Routine chemistry testing requires serum or plasma separation. CLSI PRE04 identifies tube characteristics, temperature, force, and time as processing variables. Manufacturer instructions specify the centrifugation conditions for each tube or disposable.¹

For example, BD specifies 1,000–1,300 xg for its SST™ and PST™ gel tubes, with 10-minute swinging-bucket or 15-minute fixed-angle cycles. ™ tubes require a swinging-bucket rotor and cannot be centrifuged in a fixed-angle rotor.² For labs using several different tube types, it’s important to confirm compatibility and available cycles for each tube.

Coagulation Testing

CLSI H21 defines platelet-poor plasma (PPP) as plasma with fewer than 10 × 10⁹ platelets/L and recommends one validated preparation process that consistently meets this target. The common procedure is 1,500 xg for 15 minutes at room temperature. Shorter alternatives can be used when properly verified.³

H21 notes that swinging-bucket rotors can limit cellular contamination of plasma. Braking can affect residual platelet counts, although published findings differ. H21 also recommends centrifuging coagulation samples at room temperature. Nonrefrigerated centrifuges are generally adequate for this application

For plasma frozen before lupus anticoagulant testing, or unfractionated-heparin samples frozen for APTT or anti-Xa testing, ICSH recommends a second centrifugation cycle.⁴ These workflows may require secondary tubes and additional processing capacity.

Compare RCF, cycle duration, rotor configuration, and deceleration when evaluating a centrifuge for coagulation testing. The centrifuge should be able to reproduce the complete validated procedure, not just reach a particular maximum speed. Residual platelet counts should be verified at least annually, and after centrifuge changes, maintenance, or modifications.³

Blood Bank Serology

Tube serology requires short cycles that pack red blood cells without making negative reactions difficult to resuspend. For example, Immucor recommends 15–30 second cycles at 900–1,000 xg for its ABO serum grouping procedure.⁵

Labs considering a serology centrifuge for blood banking should confirm that the centrifuge meets the tube compatibility and short-cycle requirements for its procedures. Gel-card and microcolumn procedures have different instrument requirements and should be evaluated separately.

Urine Sediment Examination

For standardized manual urine sediment microscopy, the EFLM European Urinalysis Guideline recommends 400 xg for 5 minutes with 5–12 mL of urine.⁶

Bunjevac and colleagues found different sediment particle counts when comparing 400 xg with 1,358 xg and varying tube shape, specimen volume, and supernatant removal. Their lab ultimately favored its1,358 xg procedure.⁷ These findings highlight why it’s important to choose a centrifuge based on your lab’s established preparation method rather than assuming one setting will work for every procedure.

Should You Use a Swinging-Bucket or Fixed-Angle Rotor?

A centrifuge’s rotor configuration affects how samples move during centrifugation and where sediment collects.

In a swinging-bucket or horizontal rotor, tubes swing outward into a 90-degree position during centrifugation, with sediment collecting at the bottom of the tube. In a fixed-angle rotor, tubes remain angled at approximately 45 degrees, allowing sediment to collect along the outer wall and bottom. The shorter sedimentation path of a fixed-angle rotor can reduce separation time in some applications.⁸

The right rotor choice depends on the tube type and procedure. Some collection tubes can be used in either rotor configuration, while others have more specific requirements. For example, BD gel separator tubes can be used with both fixed angle and horizontal rotors, while ™ tubes require horizontal centrifugation only.²

When deciding on rotor configuration, compare permitted rotor orientation alongside tube compatibility, force, and cycle time. Neither rotor design suits every clinical application.

What Is the Difference Between RCF and RPM?

One of the most important specifications to compare when choosing a centrifuge is relative centrifugal force, or RCF. RCF describes centrifugal acceleration at the rotor radius and is expressed as xg. RPM describes rotational speed.

RCF depends on both RPM and rotor radius. Their relationship is:

RCF (×g) = 1.118 × 10⁻⁵ × radius (cm) × RPM²

Two centrifuges running at the same RPM can produce different RCF values because their rotor radii differ. For example, at 3,000 RPM, a rotor with a 10 cm radius produces approximately 1,006 xg, while a 15 cm radius rotor produces approximately 1,509 xg.

When comparing centrifuges, use the manufacturer’s published RCF for the supplied rotor rather than RPM alone. You do not need to calculate rotor radius, but you should confirm that the centrifuge can deliver the required RCF and run time, not simply a high maximum force.

CLSI H21 identifies 1,500 xg for 15 minutes as a common PPP procedure but permits other verified conditions.³ Collection tube manufacturers may also specify different times for different rotor types. Select a centrifuge that can run the complete procedure, including any relevant braking or temperature conditions.

For more information on converting RPM to RCF, see Drucker’s guide to calculating g-force.

What Size Centrifuge Does Your Lab Need?

There is no standard tube capacity that is right for every hospital lab. Required capacity depends on tube dimensions, how many specimens are received during busy periods, the length of each cycle, and individual turnaround requirements.

Compare Capacity Using the Laboratory’s Actual Tubes

Published tube capacity applies to a particular rotor and holder configuration. A rotor holding 24 standard collection tubes may accommodate fewer large tubes or 50 mL tubes. Check the actual tube diameter, length, closure clearance, and included carriers before comparing models.

Drucker’s centrifuge tube guide provides additional information on tube dimensions and compatibility.

Estimate the Number of Runs Required

Consider 40 compatible tubes received in a morning batch. A 12-place rotor requires at least four runs; a 24-place rotor needs at least two. With a 10-minute programmed spin, that is 40 versus 20 minutes of centrifugation alone.

Add loading, acceleration, deceleration, and unloading time. Estimate the runs needed during regular peak arrivals, while allowing for STAT specimens and competing procedures.

One Larger Centrifuge or Multiple Smaller Units?

A larger centrifuge can reduce batches when tubes share one protocol. Multiple smaller units allow different cycles to run simultaneously, such as routine serum processing alongside short serology spins. Compare bench space, workload timing, maintenance, and equipment availability.

What Should Be Confirmed Before Installation?

Before purchasing or installing a new centrifuge, check the supplied components and operating requirements against the laboratory’s tube inventory and procedures.

Tube compatibility. Confirm the included rotor, buckets, carriers, inserts, tube dimensions, and closure clearance.

Balancing and loading. Follow the manufacturer’s balancing instructions for every application. Properly balanced loads reduce vibration and help prevent damage to the rotor and drive component.

Cycle controls. Check that the available RCF and run-time settings cover all intended procedures. Presets may suit dedicated applications; shared instruments may need adjustable cycles.

Maintenance. Review footprint, cleaning, rotor inspection, service, and speed/timer checks. CLSI QMS23 addresses equipment qualification and routine function checks.¹⁰

Drucker’s centrifuge calibration check resource describes procedures for checking speed and timer performance.

Replacing an Existing Centrifuge

When replacing a centrifuge, compare actual RCF, rotor geometry, and deceleration as well as capacity. Do not transfer an old RPM setting without confirming equivalent force. For coagulation, CLSI H21 recommends checking residual platelet counts after changing or modifying a centrifuge.³

Ready-to-Use Centrifuge Configurations

Drucker Diagnostics manufactures clinical centrifuges with rotors, tube holders, and all necessary accessories included. A ready-to-use centrifuge can make it easier to compare complete setups, but your lab should still confirm tube compatibility and verify that the available cycles meet your needs.

Choosing a Clinical Centrifuge

The right clinical centrifuge is the one that fits the way you work. Choose equipment that accommodates your lab’s actual tube types, produces the required RCF and time combinations, and processes peak specimen arrivals within the available turnaround time.

Drucker Diagnostics offers clinical laboratory centrifuges with ready-to-use rotors and tube holders for routine blood processing, coagulation, STAT work, blood bank serology, and other applications.

Sources

1. Clinical and Laboratory Standards Institute. Handling, Transport, Processing, and Storage of Blood Specimens for Routine Laboratory Examinations. CLSI PRE04. 1st ed. 2023. CLSI PRE04.
2. Becton, Dickinson and Company. BD Vacutainer® Blood Collection Tubes. Manufacturer centrifugation guidance for SST™, PST™, and Barricor™ collection tubes. BD product information.
3. Clinical and Laboratory Standards Institute. Collection, Transport, and Processing of Blood Specimens for Testing Plasma-Based Coagulation Assays. CLSI H21. 6th ed. 2024. Section 5.2, Centrifugation. CLSI H21.
4. Kitchen S, Adcock DM, Dauer R, et al. International Council for Standardization in Haematology recommendations for processing of blood samples for coagulation testing. International Journal of Laboratory Hematology. 2021;43(6):1272–1283. https://doi.org/10.1111/ijlh.13702.
5. Immucor, Inc. Referencells Pooled Cells for ABO Serum Grouping. Reagent instructions for use, document 300-19. FDA-hosted package insert.
6. Kouri TT, Hofmann W, Falbo R, et al. The EFLM European Urinalysis Guideline 2023. Clinical Chemistry and Laboratory Medicine. 2024;62(9):1653–1786. https://doi.org/10.1515/cclm-2024-0070.
7. Bunjevac A, Nikolac Gabaj N, Miler M, Horvat A. Preanalytics of urine sediment examination: effect of relative centrifugal force, tube type, volume of sample and supernatant removal. Biochemia Medica. 2018;28(1):010707. https://doi.org/10.11613/BM.2018.010707.
8. Beckman Coulter. Centrifuge Rotor Types. Technical reference on horizontal and fixed-angle sedimentation. Rotor types.
9. Beckman Coulter. Relative Centrifugal Field (RCF). Technical reference on rotor radius, rotational speed, and centrifugal force. RCF reference.
10. Clinical and Laboratory Standards Institute. General Laboratory Equipment Performance Qualification, Use, and Maintenance. CLSI QMS23. 2nd ed. 2019. CLSI QMS23.