Its Cold In There!: A Profile of Refrigerated Tabletop Centrifuges

Date: March 2, 1998 Chart 1 efrigeration is wonderful, especially when applied to centrifuges. Not only does refrigeration help maintain the stability of biological compounds whirling along at several thousand revolutions per minute, it also enables the use of higher speeds and g-forces. The friction encountered by a rotor spinning through the air in its chamber is enough to raise its temperature several degrees. Refrigeration counteracts this effect and thus expands the usefulness of centrifugation considerably. In this profile, LabConsumer takes a close look at refrigerated tabletop centrifuges. Best described as general-purpose instruments, these machines spin everything from microfuge tubes to 750 ml bottles, microscope slides, microplates, hematocrit tubes, and blood bags. They do so easily, often with a single rotor and a few simple bucket and adapter changes. Indeed, the workhorse swinging bucket rotors driven by these machines elegantly provide versatility and great usefulness. Coupled with their tabletop configurations, these machines give researchers access to powerful centrifugation capabilities within their personal workspaces. No longer is it necessary to march down the hall to a common machine room to use the floor-standing centrifuge. For the most part, refrigerated tabletop centrifuges employ brushless drives to run both fixed angle and swing out rotors. The fixed angle rotors presented higher speed and g-force capabilities, averaging around 14,000 rpm, with microtube rotors having the highest ratings. On the other hand, the swinging bucket rotors ran at speeds between 3,500 and 7,000 rpm but were the hands-down winners in versatility and overall usefulness. Reliance on fixed angle rotors increased with maximum speeds while volume capacities declined. Nearly all the centrifuges offered choices in acceleration and deceleration rates, ranging from the simple choice of on/off braking to the selection of one of several linear and/or quadratic profiles. Controls ran the gamut from simple, straightforward knobs and gauges to dialogue-mediated microprocessors. Typically, the machines controlled by microprocessors had memory storage for up to 100 programs. Maximum volume capacities varied from 6 x 30 ml tubes to 4 x 800 ml bottles. Instrument sizes correlated generally with capacity; that is, larger machines were needed to run bigger volumes. List prices ranged from $4,500 to $11,400. All machines were sold without accessories or rotors. All the manufacturers reported the temperature set range for their instruments, which was from about -15°C to +40°C, but only a handful offered information in their product literature about the actual controllable temperature ranges maintained by these machines. Generally, the refrigeration systems were designed to maintain a rotor near 4°C during and after a run, and maximum temperatures probably hover near the upper temperature control limit. Only two centrifuges, the CT 4.22 from Jouan and the GS-6 HT from Beckman, include a thermostated heating system to maintain temperatures above ambient levels. By and large, the refrigeration systems use CFC-free refrigerants. Below are profiles of the refrigerated, general-purpose tabletop centrifuges sold by 12 companies. Please note that several of these companies also sell high speed tabletop centrifuges, or ones that spin above 17,500 rpm, which were previously profiled by LabConsumer (M.Brush, The Scientist, September 29, 1997, page 21). Astel Enterprises PM 180R Astel Enterprises, Inc. Part of the Jouan Group of scientific instrumentation manufacturers, Astel Enterprises builds three refrigerated tabletop centrifuges. 4237R Large Capacity Centrifuge. The large capacity 4237R runs the highest capacity rotor in the profile, the swinging bucket T126 rotor equipped with 4 x 800 ml buckets. The 4237R runs the T126 at 3,200 rpm, but achieves a maximum speed of 7,000 rpm with two of its fixed angle rotors and an additional swing out rotor. The 4237R also features digitally displayed rpm values, nine acceleration and three deceleration rates, and an imbalance detector. A large array of adapters accommodates tubes and bottles between 1.5 and 800 ml, in addition to microplates. PM 180R High Speed Centrifuge. Astel Enterprises' PM 180R cranks out a maximum g-force of 20,073 xg at 17,300 rpm. Outfitted with the Multistage Program microprocessor, the PM 180R stores up to 99 programs and simultaneously displays speed, relative centrifugal force (RCF), temperature, and acceleration and deceleration rates. The higher speed applications of the PM 180R rely heavily on fixed angle rotors running a range of tubes between 0.5 and 94 ml. Adapters and rotors with sealing lids, one swing out rotor, and a 24-place hematocrit rotor are also available. 4239R High Speed Centrifuge. A high speed centrifuge, the 4239R runs up to 20,000 rpm, producing a maximum RCF of 42,029 xg. The 4239R drives one swinging bucket and seven fixed angle rotors and features digital display of actual rpm values, an imbalance detector, and self-diagnostics with warning lights. Three rotors are rated for 20,000 rpm. The highest capacity 20,000-rpm rotor runs 18 x 16 ml tubes, while the other two run 12 x 13.5 ml tubes and 24 x 1.5/2.0 ml tubes, respectively. Adapters for all the rotors fitting tubes up to 290 ml are also available. B. Braun Biotech, Inc. USA B. Braun Biotech's line of refrigerated tabletop centrifuges consists of five instruments with common characteristics. All are built around quiet, maintenance-free brushless drives and feature microprocessor control, magnetic rotor identification systems to prevent overspeeding problems, variable acceleration and deceleration curves, and rotor precooling during machine idle periods. Variations in rotor capacities, speeds, and programming features account for the differences in these centrifuges. 2K 15. The smallest centrifuge of the family, the 2K 15, runs a total of six rotors. The instrument has a maximum capacity of 6 x 30 ml, and it runs up to 15,300 rpm and 20,150 xg. A single swing out rotor holds 4 x 10 ml tubes but spins up to 10,000 rpm, and a drum rotor accommodates up to 120 micro tubes. 3K 15. The 3K 15 features an increase in maximum capacity and versatility with its ability to run a 4 x 200 ml swing out rotor and the introduction of cytology and microplate rotors into the Sigma line of centrifuges. Running at a top speed of 15,300 rpm, the 3K 15 maintains a temperature range of -2°C to ambient and controls speed to 1 rpm. 3K 30. Running only fixed angle rotors, the high speed 3K 30 zips up to 30,000 rpm and dishes out 64,390 xg. Designed with 10 quadratic and 10 linear acceleration and deceleration curves, the 3K 30's memory stores up to 100 programs. The rotor complement for the 3K 30 runs up to 36 microtubes, as well as 10, 30, 50, and 85 ml tubes in various configurations. 4K 15. B. Braun's model 4K 15 runs a battery of fixed angle and swing out rotors from a library of 10 storable programs. Among the fixed angle rotors, maximum rpm and g-forces of 15,000 and 25,160, respectively, are achieved with the 30 x 1.5/2.2 ml rotor. Tube sizes and configurations reach a high of 6 x 250 ml, which the versatile 4K 15 propels at 9,000 rpm. Four- and six-place swing out rotor designs accommodate tubes ranging in size between 7 and 250 ml, with a maximum capacity of 72 x 15 ml. Buckets for microplates are also available. 6K 15. Weighing in at 130 kg, the 6K 15 is the largest member of this group of instruments. Designed with 20 acceleration and deceleration curves and memory for 100 stored programs, the 6K 15 runs the highest capacity rotor of the group. Holding 6 x 500 ml bottles, this rotor is rated for 9,600 rpm and 17,000 g's. The 6K 15 runs a pair of four- and six-place swing out rotors similar to those used by the 4K 15 and also adds a bucket designed for blood bags. The 3K 15, 4K 15, and 6K 15 also feature a swing out rotor bucket adapter unique to this profile. Sold as a solid blank, this adapter may be custom bored to any desired tube diameter up to 50 mm. Beckman Avanti 30 Beckman Instruments GS-6R Refrigerated Tabletop Centrifuge. Beckman's GS-6R refrigerated tabletop centrifuge runs two fixed angle rotors and one high capacity swinging bucket rotor up to a maximum 6,400 rpm and 5,642 xg. Sold also in a kneewell configuration, the GS-6R features an instrument panel consisting of a simple combination of dials and switches for power, run parameters, and brake settings. Beckman's Accuset control also ensures that the GS-6R runs to within 30 rpm of set speeds. The workhorse rotor for the GS-6R is the versatile GH-3.8 swinging bucket rotor. Its four large buckets hold adapters accommodating everything from 1.5 ml microtubes to 750 ml bottles to blood bags and microplates. A separate, sealed microplate system is also available. Beckman's modular disk adapters also unstack for easy disassembly for cleaning and sterilization and to fit shorter tubes. GS-15R Multipurpose Centrifuge. Incorporating expanded run times up to 10 hours, continuous and pulse mode operation, imbalance detection and compensation, 10 acceleration and deceleration rates, and real-time RPM/RCF readings, the GS-15R powers a brushless induction drive motor. This machine cruises up to 15,300 rpm with three of its eight fixed angle rotors and handles up to 720 ml with its swinging bucket rotor. Tube sizes for the angle rotors vary between 1.5 and 85 ml, and the swinging bucket rotor holds tubes from 1.5 to 100 ml, in addition to 180 ml bottles and six microplates. Portrayed as a compact centrifuge, the GS-15R has one of the smaller footprints in the profile for an instrument of its capabilities. Avanti 30 High-Speed Compact Centrifuge. Hustling up to 30,000 rpm and generating over 64,000 g's, the Avanti 30 High-Speed Compact Centrifuge features a brushless induction drive and operates via a few simple button strokes. Offering attributes similar to those of the GS-15R, the Avanti 30 drives a contingent of 11 fixed angle rotors, a swinging bucket rotor, and a microtube bowl rotor designed to contain hazardous aerosols. Overall tube sizes for these rotors range between 1.5 and 85 ml. As a side note, Beckman manufactures the world's only benchtop ultracentrifuge, the Optima TLX. Capable of speeds of 120,000 rpm, the Optima TLX brings small-volume ultracentrifugation to the personal workspace with g-forces up to 625,000. Brinkmann Instruments, Inc. EppendorfTM Refrigerated Multipurpose Centrifuge Model 5810R and Model 5804R. Distributed by Brinkmann Instruments, the EppendorfTM line of refrigerated tabletop centrifuges consists of two multipurpose machines, the Model 5810R and the Model 5804R. Both machines spin up to 14,000 rpm (20,800 xg) and feature automatic rotor recognition systems, self-diagnostics, Fast Cool functions to precool the chamber in about 15 minutes, and standby refrigeration to maintain chamber temperature while the lid is closed. Their easy operation characteristics include quick entry of time, temperature, speed/g-force, and radius values; 34 user-defined programs; adjustable-speed short spin functions; and 10 acceleration and braking rates. The Model 5810R has been designed as a high throughput, high capacity machine, accommodating 4 x 250 ml bottles or 16 microplates and up to 36 x 15 ml or 12 x 50 ml tubes. The Model 5804R, on the other hand, spins volumes between 0.25 ml and 100 ml. Both machines run a set of five interchangeable rotors, comprising three fixed angle rotors, one swinging bucket rotor, and one microplate rotor for up to six plates. Tube sizes for the high speed angle rotors vary from 1.5 to 85 ml, whereas the swing out rotor holds tubes from 0.25 to 100 ml. Aerosol-tight covers are also available. In addition, a high capacity swing out rotor for the 5810R is also available. This rotor holds tubes up to 250 ml and has microplate buckets with space for 16 plates, the highest microplate capacity in this profile. Finally, the tube adapters for both swing out rotors are the stacking modular variety, providing support for various tube lengths and easy cleaning and sterilization. Silencer S2200 R Global Focus Marketing and Distribution Silencer S2200 R. Generating a maximum noise level of only 53 decibels, the Silencer S2200R lives up to its name, producing less noise than normal conversation (about 60 decibels). Constructed around a patented motor and rotor cooling system and including a sealed chamber with a high-strength, see-through lid, the microprocessor-controlled Silencer S2200R features dynamic braking to prevent sample resuspension, a dual lid interlock, and an imbalance detection mechanism that deactivates the centrifuge if a severe imbalance condition occurs. Three safety warning lights on the control panel indicate the lid lock status, imbalance load condition, and any electrical overloads. The S2200R runs four rotors to a maximum of 4,000 rpm and 6,500 xg. Two fixed angle rotors run 15 or 50 ml tubes at 6,500 g's, and a microplate rotor holds four plates while producing 590 xg. Its four-place horizontal rotor accommodates 4 x 250 ml bottles and has a maximum achievable RCF of 3,200 xg. This rotor's carrier system also features see-through biohazard containment covers and o-rings that may be added to the system at any time. Finally a range of tube inserts, both standard and custom, are available. Heraeus Heraeus Instruments, Inc. Labofuge 400 R. Designed for the centrifugation of average-sized samples, the economical Labofuge 400R features a microprocessor-controlled sample protection system that prevents samples from freezing, even if the rotor sits in the closed chamber for extended periods after the completion of a run. Equipped with a self-diagnostic function, the Labofuge 400 R drives a fixed angle microtube rotor to 15,000 rpm, a swing out rotor to 5,000, and a microplate rotor to 3,000 rpm. A range of Centri-Lab adapters featuring stacked modular construction for tubes up to 100 ml is available. Megafuge 1.0 R, 2.0 R, and 3.0 R. The three refrigerated members of the Megafuge series of tabletop centrifuges share several characteristics. Beginning with safety features that include automatic lid locks and interlocks, steel armored chambers, and imbalance detectors, these machines are equipped with frequency-controlled induction drives, quick run functions, microprocessor control systems, and soft braking modes that allow selective brake deactivation at a preprogrammed speed during deceleration. The Megafuge 1.0 R and 2.0 R each run a single fixed angle microtube rotor at 15,000 rpm. All three centrifuges run both a swing out and a sealed rotor. Hermetically sealed buckets and the polycarbonate lid of the sealed rotor provide complete aerosol protection. The transparent bucket covers and sealed rotor lid allow easy identification of damaged tubes so that the rotor may be moved to a secure location for opening and decontamination. For added safety, both the buckets and rotor are fully autoclavable. The maximum volumes centrifuged vary with the instrument. Specifically, the Megafuge 1.0 R handles 1.6 liters, the Megafuge 2.0 R spins 2.0 liters, and the Megafuge 3.0 R accommodates 3.0 liters. All three run microplates and have a complete line of tube adapters. An oil test rotor is available for the 3.0 R, and a specialized cyto centrifugation adapter is available for the Megafuge 1.0 R. Contifuge 17 RS. Running a battery of 11 rotors, including the only continuous flow rotor in the profile, the Contifuge 17 RS is a high-speed machine that tops out at 17,000 rpm and 25,850 g's. Microcomputer controlled with the Heraeus Sepacontrol technology, the Contifuge 17RS features 32 user programs, nine different acceleration and deceleration profiles, and a frequency controlled induction drive. The eight angle rotors propelled by the Contifuge 17RS accommodate tubes from 1.5 ml to 94 ml in various configurations with numerous reduction sleeves available. A single swing out rotor runs 4 x 100 ml tubes, and a drum rotor holds between 80 and 160 microtubes depending on their size and the adapters used. Finally, Heraeus offers a continuous flow rotor with a 300 ml sediment capacity for downstream processing and harvesting of bioproducts. Hettich Rotina 35R Andreas Hettich GmbH & Co. KG Hettich Rotina 35 R. German centrifuge manufacturer Andreas Hettich GmbH & Co. manufactures the Rotina 35 R, its entry into the refrigerated tabletop centrifuge field. Distributed in North America by RevPro Inc., the Rotina 35 R tackles the field of general-purpose centrifugation with a team of six rotors. Constructed of a powder-coated metal housing and lid, the chamber and inner lid of the Rotina 35 R consist of stainless steel and additional steel armor. Other safety traits include automatic rotor recognition, imbalance switch-off, and lid locking and holding during the rotor run. Programming is performed quickly and easily with the water-protected foil keypad. The Rotina 35 R's clearly arranged display shows speed, running time, temperature, and RCF values. A precooling program cools the instrument before samples are placed into it, allowing the samples to maintain their temperature. The Rotina 35 R's lone angle rotor is a 30-place microtube rotor equipped with a hygienic lid and is rated for 15,000 rpm and 23,646 xg, the maximum speed and RCF values produced by this machine. A 10-place swing out disc rotor for 50 ml culture tubes is available, along with a 4-place microplate rotor and a 10-place stainless steel cyto-rotor for microscope slides. Additional cyto accessories are also available from Hettich. Two swing out rotors, a 4-place and a 6-place, spin tubes falling between 1.5 and 100 ml. IEC CentraTM International Equipment Company (IEC) Centra-CL3R. Built as a general-purpose centrifuge with a low profile, the Centra-CL3R accommodates up to 4 x 250 ml bottles in addition to the usual spectrum of popular tubes. These include 15 ml, 50 ml, and 225 ml conical tubes, along with Vacutainer tubes to 15 ml, microtubes, microplates, microscope slides, and an assortment of filtration devices. A quiet, maintenance-free brushless motor spins up to 8,500 rpm and produces 6,425 xg with acceleration and deceleration rates of under 45 seconds. With memory for 99 programs, the Centra-CL3R features two timing modes: the standard "At-Start" timing, which begins when the start button is pushed, and the unique "At-Speed" timing, which begins when the rotor reaches 95 percent of its set speed. The Centra-CL3R runs many of IEC's rotors, including the versatile 243 swinging bucket rotor equipped with IEC's special aerosol-containing carriers called Aerocarriers. Centra-GP8R. Equipped with the IEC SmartSet Centrifugal Control System, the Centra-GP8R offers 3-liter (4 x 750 ml) capacity and speeds to 5,600 rpm and 4,630 xg. Constructed using international symbols and a membrane touch control panel, the SmartSet Control System stores 35 programs and enables the user to easily select the required temperature, speed/g-force, time, and acceleration and deceleration profiles. A rotor/radius function allows modification of the radius of rotation to match specific rotor/accessory combinations. The Centra-GP8R's rotor fleet runs a spectrum of tubes, bottles, bags, plates, and slides, with aerosol protection offered as the norm instead of the exception. According to IEC, "literally hundreds" of rotor and accessory combinations are available. MP4R. Offering higher speeds and g-forces (14,000 rpm/16,750 xg) than the other two machines, the MP4R and its nonrefrigerated sister are billed as the world's most versatile benchtop centrifuges. Equipped with the SmartSet Control System, the MP4R provides plenty of applications. These include microcentrifuge applications for up to 60 microtubes and over 16,000 g's per run, large volume (4 x 250 ml) spins to 3,300 xg, large batch processing accommodating up to 48 x 5 ml tubes per run, high speed pelleting to over 14,000 xg, slow start and stop controls for density gradient spins, microplate runs, and specialty applications such as TB sputum, slides, hematocrits, and concentrators. IEC sells a bevy of rotors endowing the MP4R with its great versatility. Jouan CR31 Jouan, Inc. Operating from the new Jouan Global Center in Winchester, Va., Jouan has five entries in the refrigerated tabletop centrifuge category, including the CT 4.22, the only thermostated centrifuge in this profile. BR4i. The maintenance-free induction motor of the BR4i drives an eight-member contingent of rotors up to 14,000 rpm and 18,407 g's. Accommodating tubes from 200 µl to 200 ml, these rotors also handle microscope slides and run a set of two sealed microplate carriers. The BR4i also features five personalized memories whose names the user can write next to the appropriate direct recall key, a precool function, a pulse key for short runs, and a set of five acceleration and deceleration rates. Additionally, Jouan's patented Auto-Lock function enables rotor installation in less than 5 seconds. CR3i. Possessing features nearly identical to those of the BR4i, and spinning up to the same 14,000 rpm, the CR3i runs a larger maximum volume and more tubes per spin than its counterpart. Holding four 280 ml bottles instead of 200 ml bottles, the CR3i also runs twice as many 7 and 15 ml tubes, for example. CR 4.12, CR 4.22, and CT 4.22. The refrigerated members of Jouan's C-series centrifuges, the CR 4.12, CR 4.22, and the CT 4.22, all spin up to 8,000 rpm and 9,320 xg. Designed to spin a range of tubes, vials, bottles, plates, and microscope slides, these machines can handle blood collection tubes, blood bags, microplates, culture tubes, and bottles in one swing out rotor by merely changing buckets, carriers, and inserts. Other swing out rotors handle bottles up to 750 ml, and six angle rotors accommodate 15, 50, and 100 ml tubes, plus microcentrifuge tubes. Jouan offers sealed buckets for aerosol containment that have been certified by the Centre for Applied Microbiological Research, Porton Down, U.K. Differences between the C-series centrifuges are found in their electronics. The CR 4.12 uses classical electronics, whereas the 4.22 machines are microprocessor controlled. The microprocessor features a guided dialogue response method of programming, stores 50 programs, and includes a sophisticated autotest procedure for the instrument's main components. Refrigeration control for the C-series centrifuges extends from -8°C to +40°C, with the exception of the thermostated CT 4.22. The CT 4.22 possesses a combination of heating and refrigeration systems that span a temperature range of -8°C to + 60°C, ensuring precise temperature control above ambient levels. Hermie Z400K National Labnet Company Hermle Universal Laboratory Centrifuge Z400K. Distributed by National Labnet Company, Hermle's Universal Laboratory Centrifuge Z400K handles sample volumes from 0.25 to 250 ml in both swing out and angle rotors at speeds up to 13,500 rpm and 17,321 xg. Packed with features, the Z400K offers microprocessor control, an induction drive, automatic rotor detection, a momentary button for timed quick spins, imbalance detection with safety shutdown, overspeed prevention, and an electronic lid lock mechanism. Knobs control the digitally displayed speed, time, and temperature settings, and g-force conversion software allows the setting and/or display of RCF parameters. Angle rotors include microrotors that produce up to 17,000 xg and high capacity rotors accommodating 50 ml tubes. Swing out rotor configurations include high capacity rotors for 15 and 50 ml tubes, a 4 x 250 ml rotor, and two economy packages complete with buckets. Hematocrit and microplate rotors are also available. Hermle also provides inserts for most popular tube sizes in addition to custom rpm and 21,130g's. Its digital control panel provides memory for three programs, a Flash function for momentary spins, a Soft Brake function, and a common Jog Dial that combines the ease of analog control with the accuracy of digital microprocessors. Parameter settings are performed by simply choosing Temp, Time, or Speed and then turning the dial to the required setting. Designed for the centrifugation of smaller volumes, the TX-160 runs its highest capacity rotor (4 x 50 ml) at 15,000 rpm and over 19,000 g's. Nine fixed angle rotors accommodate tubes from 0.25 to 50 ml, while a swinging bucket and horizontal rotor run between 16 and 80 microtubes. Sorvall RT7 Sorvall Products, L.P. RT7 and RT7 Plus Refrigerated Tabletop Centrifuges. Sorvall offers two refrigerated tabletop centrifuges, the RT7 and the RT7 Plus. The RT7 Plus, with its brushless DC motor and integrated drive, is perfect for high-volume processing applications or for frequent use where clean room requirements exist. The brushless motor reduces maintenance and reduces brush dust associated with "classic" motor designs. The RT7 provides similar performance specifications with the "classical" brush-type drive for less frequent usage. Both machines accelerate to a top speed of 7,000 rpm and 5,856 g's while offering an automatic slow start to 500 rpm and braking to 200 rpm, followed by coasting to a stop. These machines are low in height, providing easy access for loading and unloading and one-handed door operation. Providing up to 50 percent more g-force and three times the capacity of other comparable centrifuge models, the RT7 machines run two swinging-bucket and one fixed angle rotor. Each accepts a wide range of tube adapters, accommodating everything from 1.5 ml microcentrifuge tubes to 750 ml bottles with a maximum volume capacity of 3 liters. For added safety from infectious, radioactive, and other hazardous materials, Sorvall's rotors have been independently tested for biocontainment capabilities by the Centre for Applied Microbiological Research, Biosafety Testing Section, U.K. Tomy Tech USA, Inc. Tomy TX-160 Refrigerated Tabletop Microcentrifuge Incorporating a profile-reducing, rear-mounted refrigeration system to make better use of valuable bench space, the TX-160 incorporates a brushless induction drive capable of accelerating selected rotors to 15,000 rpm in 6 seconds. The TX-160's maximum obtainable speed is 16,000 rpm and 21,130g's. Its digital control panel provides memory for three programs, a Flash function for momentary spins, a Soft Brake function, and a common Jog Dial that combines the ease of analog control with the accuracy of digital microprocessors. Parameter settings are performed by simply choosing Temp, Time, or Speed and then turning the dial to the required setting. Designed for the centrifugation of smaller volumes, the TX-160 runs its highest capacity rotor (4 x 50 ml) at 15,000 rpm and over 19,000 g's. Nine fixed angle rotors accommodate tubes from 0.25 to 50 ml, while a swinging bucket and horizontal rotor run between 16 and 80 microtubes. Chart 1 Michael Brush is an Associate Scientist and Radiation Safety Officer at Hitachi Chemical Company in Irvine, Calif. He can be reached online at MDBrush@compuserve.com.

Its Cold In There!: A Profile of Refrigerated Tabletop Centrifuges

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