FAQ

Selection is not about speed but about the centrifugal force (RCF) your sample requires. For cells, bacteria, protein precipitation and nucleic acid prep that need high g-force, choose a high-speed model; for routine clinical separation of serum, plasma and urine, or large-volume supernatant work, a low-speed model is enough. If the sample is temperature-sensitive, add refrigeration to the requirement.

The dividing line is bench space versus throughput per run. Benchtop models sit on the workbench, are ready to use at any time and occupy little space, handling routine small-to-medium volumes with capacities up to 4 × 750 ml. Floor-standing models stand on the floor and accept large-capacity rotors (up to 6 × 2400 ml), suited to batch work in blood centres, biologics production and industrial solid–liquid separation.

Whenever the sample is temperature-sensitive: cells, enzymes, antibodies, nucleic acids, viruses and clinical chemistry items can lose activity or change results when the run warms up. Heat is generated at the rotor and tube walls, so ambient models are more prone to warming during long continuous runs. MRK refrigerated models hold −20 °C to +40 °C, with both static precooling and dynamic temperature control.

Work backwards from samples per batch × volume per tube × batches per day. If you routinely run 24 × 15 ml tubes, choose a rotor that holds all 24 in one go — splitting into two runs doubles the waiting time and extends sample exposure. A 20–30 % margin is enough; running more batches is cheaper than sizing for peak load.

It depends on whether the use is single-purpose. For serum separation alone, one swing-out rotor is sufficient. But labs usually handle 15/50 ml conical tubes, 1.5/2 ml microtubes, blood collection tubes and 96-well plates, and one rotor with several adapters is often better value than several rotors. List the consumables you actually use before ordering, then have the supplier configure the adapters.

Cell harvesting and washing typically run at 300–1500 ×g at 4 °C for short periods, so gentleness and temperature control matter most: choose a refrigerated benchtop model with a swing-out rotor (a flat settling surface is less likely to damage cells) and a low deceleration setting to avoid shear during resuspension. High speed is not the goal — excessive g-force can lyse cells or alter their adherent state.

Routine clinical practice uses a low-speed swing-out rotor: serum at about 3000–4000 r/min for around 10 minutes; plasma at a higher g-force as the assay requires, with anticoagulant tubes. A swing-out rotor gives a flat interface and keeps red cells out of the serum. For high sample volumes, prefer a model with automatic cap removal to skip opening tubes one by one.

Nucleic acid extraction means frequent short spins (30 seconds to 2 minutes, repeated many times), so microtube fit, fast acceleration and deceleration, and optional temperature control matter. A refrigerated benchtop high-speed model with a 1.5/2 ml angle rotor is the usual choice; for 96-well plate protocols, add a microplate rotor. Caps must be firmly closed — samples opened repeatedly are more prone to leakage at high speed.

It covers the vast majority of laboratory work: 4 °C for cells, enzymes, antibodies and clinical samples; the ambient range for routine separation; below −10 °C for special low-temperature precipitation. What actually affects results is the real temperature and its fluctuation inside the rotor chamber, not the lower limit printed on the panel. For highly temperature-sensitive work, measure the chamber temperature once under load.

It works but is awkward — a 96-well plate does not fit a conventional angle rotor, and forcing it in can warp the plate. Use a microplate rotor, or a dedicated microplate mini centrifuge (2 × 96 wells, 3000 r/min class) that brings droplets on the walls to the well bottom in seconds. This step needs no high g-force, only steady rotation without deforming the plate.

With dozens to hundreds of tubes a day, an automatic decapping model is advisable: the rotor carries a decapping structure that separates cap from tube at the end of the run, removing manual opening and reducing aerosol exposure. Departments with low volumes that mostly open tubes by hand can use a standard swing-out rotor with a biosafety lid — no need to buy dedicated equipment for it.

The core requirements are large capacity, a swing-out rotor, blood-bag cups and stable temperature control. One batch should hold several bags so a single donation pool is not split across runs with a time gap; the cups must secure the bag and prevent folding or squeezing during the spin. MRK floor-standing refrigerated models offer up to 6 × 2400 ml with blood-bag rotors, suited to blood centres and batch biologics work.

Teaching labs are characterised by many users, mixed consumables and low demand for extreme performance. One refrigerated benchtop high-capacity model with several adapters covers 15 ml, 50 ml, blood tubes and microtubes — cheaper than two or three single-purpose machines. Choose simple controls and a reliable lid interlock to reduce operator error.

Three routes: ① choose a benchtop model, which uses less than half the floor space of a floor-standing unit; ② handle 1.5/2 ml microtubes and PCR strips on a mini centrifuge no bigger than a cup; ③ consolidate large-volume work into one machine and keep only small units elsewhere. Leave clearance around the cabinet for heat dissipation — boxing it in reduces cooling efficiency.

Look first at the rotor coverage of existing equipment rather than buying another similar machine. Typical gaps: ① large capacity (blood bags, large bottles of supernatant); ② blood-tube decapping (manual opening becomes a bottleneck once clinical volume rises); ③ microplate spin-down; ④ a mini centrifuge, since small-volume high-frequency work should not tie up a large machine. Filling these gaps usually improves throughput more than another high-speed unit.

MRK centrifuges span speeds from 3,000 to 21,000 r/min, with capacities from 0.2 ml to 6 × 2400 ml. Products split into low-speed and high-speed classes, each available in ambient or refrigerated form, giving four main series: high-speed, low-speed, high-speed refrigerated and low-speed refrigerated.

MRK refrigerated centrifuges cover a temperature range of -20℃～+40℃, using an imported compressor unit with both static precooling and dynamic cooling to hold temperature throughout the run and protect temperature-sensitive samples.

Centrifugal force is what determines separation; speed is only the rotor's angular velocity. The same 3000 r/min produces two to three times different g-force on rotors of different radius. When a paper or reagent datasheet specifies ×g, always set by g-force; only when it gives r/min together with the rotor model can you copy the speed directly.

No. A high maximum only states the ceiling, not what your sample needs. Most clinical and cell work runs at 3000–5000 r/min; genuinely high speeds are for subcellular fractions, plasmid prep and virus concentration. Paying for a ceiling you never use brings more noise, more heat and faster rotor wear. Size to the maximum g-force you actually need, with a 20 % margin.

That is normal. The speed limit is set jointly by motor and rotor: large-capacity rotors are heavy and carry high centrifugal stress, so they must run slower or the shaft can fail. The quoted maximum therefore usually refers to a small angle rotor. When selecting, ask what the rotor you intend to use can actually reach rather than reading the headline figure.

Judge it in two categories. Steady airflow noise under no load is normal (fan and air movement). Rhythmic knocking, periodic rumbling or the unit physically moving are abnormal — usually imbalance, an unsecured rotor, worn damping pads or bearing trouble — and the run should stop immediately for inspection. An uneven surface or missing feet amplify vibration.

Follow the rotor manual, not the instrument's headline figure. Adapters add inertia and load, and some configurations limit the maximum speed. Whenever you change tube size, add sleeves or use adapters of a different material, confirm the permitted speed and g-force on the corresponding line of the manual; exceeding it bursts tubes first and overstresses the rotor second.

RCF = 1.118×10⁻⁵ × r × n², where r is the rotor radius in cm and n the speed in r/min; the result is in ×g. Inverting it: n = √(RCF ÷ (1.118×10⁻⁵ × r)). In practice it is safer to read the speed–g-force table in the rotor manual, because conventions differ on whether r is the maximum or the average radius, and a hand calculation drifts.

Yes, but judge it by chamber temperature under load, not the panel reading when empty. An empty chamber cools quickly and looks impressive; once loaded, the temperature rises noticeably. For enzyme, antibody and cell work, verify the actual temperature and its fluctuation once at full load with an independent thermometer — more meaningful than the accuracy figure in the manual.

The usual practice is to set the temperature and precool for 15–30 minutes, so the rotor itself cools as well — chilling only the chamber leaves the sample touching room-temperature metal. If time is short, run briefly at high speed with no load to speed cooling. Avoid long empty runs at low temperature: frost build-up affects balancing and the lid lock.

Two purposes: ① protecting the sample — braking too hard disturbs the sedimentation interface, so cell and density-gradient runs must decelerate slowly; ② saving time — routine separation can use a fast ramp. Density-gradient and isopycnic runs must never brake abruptly or the layers are destroyed. Ramp numbering differs between manufacturers; follow the manual.

It means six positions, up to 1000 ml each — several litres of batch capacity in total. The usable capacity depends on the rotor bores and adapters: a 1000 ml position may hold several 50 ml conical tubes, or may need a different adapter. It is more reliable to state the tubes you need to run at once and let the supplier configure the rotor.

The k factor expresses the relative time a particle needs to pellet — the smaller the k, the faster. Switching rotors on the same machine changes k several-fold, so run times must be adjusted. In practice: if a rotor with k₁ needs t₁ minutes, a rotor with k₂ needs about t₁ × k₂ / k₁. Useful for method transfer or changing instruments.

An angle rotor has a short settling path, spins fast and gives high throughput, but the pellet collects on the slanted tube wall. A swing-out rotor throws tubes horizontal, so the path is longer and the interface flat, which suits work needing a clean interface such as serum and density gradients. At the same g-force a swing-out rotor is usually slower but produces a tidier result.

The key point is that the tube's rated g-force must exceed the g-force you set. Ordinary PP tubes are usually rated around 12000 ×g; ultracentrifugal and dialysis tubes follow the manufacturer's figure; glass tubes tolerate less and leave fragments when they break. The most common consequence of over-speeding is a cracked tube bottom or a cap flying off, ruining both sample and chamber. Check the max RCF marking on the tube wall before use.

Yes. Aluminium rotors suffer metal fatigue, especially after high-speed use, frequent cycling and contact with corrosive liquids; cracks can appear and eventually lead to failure. The accepted practice is to log cycles and age, and to inspect the body, threads, locking mechanism and any corrosion pitting at the manufacturer's recommended interval. Any crack, deformation or worn thread means the rotor must be retired — never welded or repaired.

Its main jobs are spinning down 96-well plates and pelleting inside the plate: driving droplets on the walls to the well bottom after loading, attaching cells to the plate by centrifugation, and collecting residual liquid after ELISA washing. These steps need little g-force — what matters is a firmly seated plate and steady rotation without deformation. A rotor that takes two plates at once doubles throughput.

It spins cells in suspension directly onto a glass slide to make a smear. Samples with few cells — cerebrospinal fluid, pleural or ascitic fluid, urine, fine-needle aspirates — are easily missed on conventional smears. After centrifugation the cells lie in a single layer within a defined area, with intact morphology for staining and microscopy. Speeds are in the 3000 r/min class; the cells are deposited by centrifugal force rather than friction.

Through a decapping structure on the rotor working with a cover plate: the tube body is held while the cap is restrained axially, and centrifugal force separates the two into their own compartments, so the whole tray of caps can be lifted out afterwards. It saves opening tubes one by one and reduces aerosol exposure — provided tube specifications are uniform. Mixing brands often leaves caps partly attached or jammed.

PP (polypropylene) is the most common: good chemical resistance, autoclavable, only moderately clear. PC (polycarbonate) is transparent and strong, suited to high-speed work where layers must be seen, but it does not tolerate strong alkalis or some organic solvents. PPCO balances clarity and chemical resistance and is often used where the interface must be visible. With organic solvents, check the manufacturer's chemical compatibility table first.

Yes, but with the matching adapter or sleeve, and within the tube's own g-force limit (most conical tubes are rated around 3000–5000 ×g — check the wall marking). A 50 ml tube in a swing-out rotor needs a proper sleeve, otherwise it shifts and causes imbalance. Do not fill above the printed graduation: a full conical tube is more likely to split at the shoulder at high speed.

Not full — generally two-thirds to three-quarters of the tube volume. Too high and the liquid hits the cap at speed, leaks, or sprays out to contaminate the chamber and create aerosols; too little and the layer is shallow with an interface hard to read. Leave extra room with a swing-out rotor, since the tube swings horizontal and the surface climbs the wall.

Yes, but three conditions must hold at once: matching dimensions, adequate g-force rating and matching bottom shape. The last is the risk — an angle rotor bore is conical, so a flat-bottomed tube concentrates stress and cracks, while a conical tube in a flat-bottomed bore shifts about. For critical samples use original or explicitly compatible consumables.

Mainly for micro-haematocrit (HCT) determination: blood is drawn into a capillary, spun at high speed, and the ratio of the red cell column to the whole-blood column is read. Such rotors are built to capillary dimensions — high speed, small capacity. Most hospitals now use haematology analysers instead, but primary care and research still need them; confirm the capillary specification matches the rotor when selecting.

It depends on the rotor model and bore type. A typical swing-out rotor accepts adapters for 15 ml, 50 ml, blood tubes and urine sediment tubes, but every added adapter brings its own speed limit and balancing requirement. List all the containers you intend to use when ordering and ask for a rotor-plus-adapter combination table, so you do not discover later that a particular tube will not fit.

Four steps: ① is the rotor locked, crack-free and free of corrosion; ② are opposite tubes balanced, including adapters and sleeves; ③ are caps tight and liquid levels not too high; ④ is the chamber free of broken tube debris or liquid from the last run. On refrigerated models, also check for heavy frost. Ten seconds each, and most accidents are prevented.

The principle is symmetry of equal mass; in practice adjust opposed tubes to within 0.1 g on a balance, weighing adapters together with the tubes. Without a balance, use equal volumes of liquid of the same density. With several tubes, load them symmetrically around the rotor rather than filling one side; an odd tube must be paired with a balance tube of water.

No — unless the rotor is specifically designed to allow single-tube operation. A balance tube with an equal volume of water must be placed in the opposite position. Running one tube at speed causes severe vibration: at best the imbalance sensor stops the run, at worst the spindle and damping components are damaged. Tap water is fine for the balance tube, matched in mass to the sample tube — never use an empty tube as a stand-in.

Yes. During a run there is a pressure differential and liquid surges against the cap; a loose cap leaks, liquid enters the rotor bore causing corrosion and imbalance, and pathogen-containing samples form aerosols. Screw caps with an O-ring are more reliable than push caps. If liquid is found on the rim, clean it before loading — never run with liquid on the outside.

No — and the lid interlock must never be bypassed. Opening at speed throws out samples and debris; it is the most serious accident type in a centrifuge. Proper instruments interlock the lid until the rotor has stopped. If the interlock fails and the lid can be opened, take the unit out of service and call for repair rather than using it carefully.

Wait until the rotor has fully stopped, then pause another ten-odd seconds before opening. Opening right after a forced stop lets air movement and any aerosols escape — the highest-risk moment when handling pathogens. Open in a biological safety cabinet where possible, or use sealed cups or a biosafety rotor.

First convert ×g to the speed for that rotor (most instruments switch to RCF mode so you can enter ×g directly, which is simpler), then set 4 °C and the time. If the machine only accepts speed, convert from the rotor table rather than estimating. Reconvert whenever the rotor changes — with a large rotor fitted, the same speed produces a very different g-force.

Stay nearby at least through the acceleration phase. Abnormal vibration, odd noises and metallic scraping almost always show up between start-up and reaching set speed, and that is when a problem escalates fastest. Leave once the run is smooth and the noise normal, and if possible come back once per cycle to check.

Handle it gently and do not rock the tube, or the freshly formed interface re-mixes. Aspirate with the tip against the wall, 1–2 mm below the surface, and keep it away from the pellet. If the pellet is needed, pour off the supernatant in one movement — repeated pouring tends to carry the pellet out.

Set the temperature and precool, rotor included → load samples → run → remove samples promptly afterwards. Do not put room-temperature samples into a chamber that has just been switched on: the temperature first rises and then falls, producing a large excursion. Nor should samples sit in the chamber for long after the run — warming can thaw and refreeze them repeatedly.

Press stop and let it decelerate on the set ramp; do not cut the power. Cutting power lets the rotor coast for a long time, and some models log it as an abnormal shutdown. Use the emergency stop or mains switch only for violent vibration, unusual noise or smoke, and inspect the rotor and chamber before using the instrument again.

Yes. A refrigerated unit carries a heavy cooling load during continuous operation, so chamber temperature drifts upward, and the motor and rotor bearings also warm. Let it idle for a few minutes every two or three batches so the temperature recovers, and watch whether the panel reading is stable. Long high-load runs also cycle the compressor more often and shorten its life.

After each use, wipe the chamber and rotor bores with a soft cloth and a neutral detergent or 75 % ethanol, paying attention to spilled liquid and debris, then dry with a clean cloth and leave the lid open to air. Do not use steel wool, strong acids or alkalis, or copious water — the chamber is usually coated steel and scratches rust, while water reaching the motor is worse still.

Wash the bores with warm water and a neutral detergent using a soft brush, rinse, then invert to dry — never bake them dry. Aluminium rotors must be kept away from strong alkalis, strong acids and chlorine disinfectants; keep threads and seating surfaces clean and apply a thin film of silicone grease if needed. After each wash, check the bore bottoms for corrosion pitting and cracks; that inspection decides whether the rotor may stay in service.

Speed and temperature should be calibrated annually, especially in clinical laboratories and GMP or CNAS-accredited facilities, where audit usually asks for the certificate. Measure speed with a non-contact tachometer and temperature with a calibrated thermometer under load. Between calibrations, compare the panel reading against an empty run and report any drift.

For short contact, yes, but the residue must be wiped off. Chlorine disinfectants are aggressive towards aluminium rotors and long-term residue causes pitting and cracking. The proper sequence: clean first, apply a suitable disinfectant for the specified contact time, then wipe with water or ethanol and dry. Rotors must never be left soaking in disinfectant.

Yes. Frost takes up space, disturbs balancing and can freeze the lid lock. Switch off, open the lid and let it thaw naturally, or remove it gently with a soft plastic scraper and wipe dry; never chip at it with metal tools, which score the chamber and evaporator. Frequent frosting usually means a poor lid seal or long periods with the lid open — check the seal first, then defrost.

Wipe it clean periodically and apply a thin film of silicone grease to keep it supple and sealing. A hardened gasket causes frost, reduced cooling and more noise. Check for stiffness, cracks, deformation or poor compression; replace with a genuine part rather than gluing it or packing it with shims, since a leak also upsets temperature control.

Three tiers: after every use clean the chamber and tube bores; monthly inspect the rotor body, threads and gasket and clear the drain and vents; annually carry out a full inspection plus speed and temperature calibration. For units used several times a day, move the monthly items to every two weeks. Record the results — rotor life management depends on that log.

A little condensation is normal, but standing water needs investigating. Common causes: a blocked drain, a hardened chamber gasket, sample spillage that was not cleaned up, or high ambient humidity. Wipe it up, clear the drain, and if it recurs together with poorer cooling, call service — do not keep running the unit with water inside.

Current models use brushless DC motors, which are maintenance-free and have no brushes. If your unit has an older brushed motor, carbon dust and wear accumulate and the brushes need replacing at the manufacturer's interval. Check the motor type in the manual, or watch for unusual sparking noise and unstable speed. Note that brushless does not mean the whole instrument needs no servicing.

Empty and dry the chamber, and store the rotor separately so it is not deformed by long-term load; leave the lid ajar to prevent mould. Disconnect the power rather than leaving it on standby. Before reuse, check the rotor for corrosion and cracks and the lid lock for correct operation, then run it empty once before loading samples.

Nine times out of ten it is balancing: opposed tubes differ too much in mass, one tube was run without a balance tube, an adapter is not seated, or a tube sits crooked in its bore. Next come an unlocked rotor, and missing or uneven damping feet. Remedy: remove everything, rebalance symmetrically (weighing adapters with the tubes), confirm the rotor is locked, level the machine and try again. If it recurs, check whether the dampers have aged.

Check in order: is the plug and socket live → has a fuse or breaker tripped → is the power cord damaged → is the lid fully closed (some models will not start otherwise). If all that is fine and there is still no display, the power or control board is the likely fault, which is a service matter — do not open the unit yourself. The instrument must be reliably earthed.

First check whether the rotor was changed: each rotor has its own speed limit and the instrument caps the setpoint accordingly. Then check whether over-speed protection tripped because the setpoint exceeds the rotor's rating. Other possibilities: excessive motor load, a slipping belt on older units, or current limiting on the control board. Always start by confirming the maximum speed of the rotor currently fitted.

In order of likelihood: ① rotor imbalance or bearing wear, usually a periodic rumble; ② aged or missing damping feet; ③ foreign objects or broken tube fragments in the chamber; ④ dust on the fan; ⑤ a leaking gasket causing air noise. Clean and re-check balancing first; if the noise comes with obvious vibration, stop using the unit at once to avoid spindle damage.

Rule out operational causes first: is the lid properly closed, is the chamber heavily frosted, is ambient temperature too high, are the vents blocked. If all that is in order and it still will not cool, the compressor may not be starting, refrigerant may have leaked, or the temperature probe may have failed — that needs service. Frequent lid opening also keeps the temperature from settling.

First confirm the rotor has fully stopped (some models need tens of seconds before unlocking), then check whether an alarm lock is active from imbalance or over-temperature; clearing the alarm usually releases the lock. If the panel has a manual release, follow the manual. If it keeps happening, the lock mechanism or sensor is faulty and needs service — never force it with a tool.

Stop immediately and do not run it again. Metallic scraping usually means the rotor is touching the chamber, a bearing has failed, or the spindle is deformed; continuing can lead to rotor failure with serious consequences. After stopping, remove the rotor and inspect for scoring and deformation, turn it by hand to listen for noise, then call service. This is not a fault to work around by running slower.

Stop the run, isolate the power, remove the rotor, then disinfect chamber and rotor according to biosafety rules. For pathogen-containing samples follow the laboratory contamination procedure, with adequate disinfectant contact time; rinsing with water alone is not acceptable. Dry thoroughly before reassembly and check that the drain is not blocked. If liquid reached the motor or bearings, service must dismantle and inspect.

Not necessarily. The panel shows the chamber probe, not the sample temperature; room-temperature samples just loaded need time to equilibrate, and a full load raises the chamber temperature. To check: place a control tube of water in the rotor, run for ten minutes, then measure it and compare with the setpoint. A persistent deviation above 2 °C calls for calibration or service.

The meaning must be looked up in the supplied manual or confirmed with the manufacturer; the same code can mean something entirely different on another model, so acting on an internet explanation is risky. General handling: note the code and the conditions when it appeared (speed, load, temperature), power-cycle once, and if it returns report the code to service — most cases can then be traced directly to a sensor or driver board.

Check three directions: ① the g-force actually delivered has dropped (rotor changed, set speed not reached, belt slipping); ② the sample itself has changed (anticoagulant, standing time, temperature); ③ operator differences (ramp settings, fill volume, delay before sampling). Verify the rotor and setpoints first, then re-run a standard sample for comparison.

The core requirement is aerosol containment: use rotors with lids or sealed cups, a biosafety rotor where appropriate, and caps that seal properly. Let the unit stand for ten-odd seconds before opening the lid and work in a biological safety cabinet as far as possible. Place the instrument away from walkways and follow the contamination procedure immediately if a tube breaks. Open swing-out rotors are not advisable for high-risk samples.

Neither method sterilises the whole instrument. UV only reaches surfaces, penetrates poorly, and ages plastics over time; heat damages the motor, seals and electronics. The correct approach is surface disinfection with a suitable disinfectant, plus separate treatment of removable parts. Where sterility is needed, rely on single-use sterile consumables and a safety cabinet rather than sterilising the machine.

Not advisable. Aluminium rotors suffer metal fatigue and the risk of failure rises markedly past their service life — and failure usually happens at high speed, with severe consequences. Age alone is not the criterion: use frequency, contact with corrosive liquids, and any cracks or pitting all count. Once the manufacturer's recommended life is reached, or a defect is found, the rotor must be retired rather than watched.

Use sealed rotors or airtight cups and work in a fume hood or dedicated area; loading, opening and cleaning must follow the protection level for that hazard. Clean the rotor separately afterwards and, ideally, dedicate it to that use. Radioactive work also requires waste disposal and contamination monitoring. Confirm the rotor's sealing class with the supplier before deciding whether it is suitable.

Stop the run, isolate the power, then put on gloves and eye protection before touching anything. Lift out the whole rotor rather than picking fragments out of the chamber; remove the glass with forceps, then disinfect the chamber and rotor bores following the contamination procedure and dry thoroughly. Inspect the bores for scoring and deformation; if fragments reached the spindle area, service must dismantle it. Switch to plastic tubes with a higher g-force rating afterwards.

Use an earthed three-pin socket, preferably on a dedicated circuit, and do not share a power strip with high-current equipment. Poor earthing sharply raises the risk of electric shock; in damp environments fit residual-current protection. Never route the cord under the instrument's feet or leave it sharply bent. Always disconnect power before moving the unit.

Level, ventilated, out of direct sunlight, away from heat sources and vibration. Leave clearance on all sides for heat dissipation — especially at the back — and do not box the unit into a closed cabinet. Set it on a level bench and adjust the feet if needed. High ambient temperature markedly reduces cooling performance on refrigerated models, and adjacent shakers or homogenisers can disturb balancing.

Typically an equipment file covering purchase, installation and acceptance; an SOP; usage and maintenance records; and a calibration certificate. Critical equipment may also require IQ/OQ/PQ validation. Auditors are looking for traceability: who used it, how it was maintained, whether the data are reliable. Ask the supplier for calibration certificates and validation support at the purchasing stage.

At minimum four topics: balancing and loading, speed/g-force conversion, recognising abnormality (vibration, unusual noise) and emergency handling (stop, spill, broken tube). A one-page SOP beside the instrument, listing the speed, time and temperature of routine programmes, reduces setting errors from memory. Keep training records — they are a common audit item.

For two years from the date of installation, factory-trained engineers carry out repairs free of charge; after that, lifetime maintenance is available. The warranty covers manufacturing defects in the equipment itself; damage caused by misuse or by non-genuine parts is normally excluded. The contract and the warranty card supplied with the unit govern the details.

Generally a call-out or return-to-factory service fee plus the cost of replacement parts, quoted against the actual fault and confirmed before any replacement. Out-of-warranty units should still have an annual inspection — dealing with small faults early is far cheaper than a major overhaul. For heavily used machines, a maintenance agreement fixes response times and spare-part prices.

It depends on the region and the type of fault. MRK has marketing centres in Shanghai, Beijing, Guangzhou, Changsha and Chengdu providing local support; simple problems can often be diagnosed by phone or remotely first, with an on-site visit arranged if needed. Put the response time in the contract rather than relying on a verbal assurance.

Normally on-site installation and commissioning plus operator training are included: installation covers the supply, levelling, an empty test run and a first check of speed and temperature. Have the people who will actually use the instrument attend the training rather than a purchasing representative, and finish by running a real protocol on site — more useful than watching a demonstration.

Common wear parts include lid gaskets, seals, adapters, damping feet and fuses, all standard spares; key items such as rotors and main boards are supplied per model. Ask about the spare-part support period for the model when purchasing, and keep a set of wear parts in the lab so a minor fault does not mean waiting for a shipment.

Preparation is needed: disconnect power, remove and pack the rotor separately, secure the lid lock and drain condensate. Keep the unit upright while moving, avoid severe shocks, and keep the original packaging if possible. After reinstalling, let it stand before powering up (especially refrigerated models), check levelling and earthing, and run it empty before loading samples. Large floor-standing units are best moved with the manufacturer's help.

Mainly capacity and throughput, maximum g-force, the refrigeration system, rotor configuration, control and safety features (rotor recognition, imbalance detection, stored programmes), plus brand and service network. Cheaper models economise on rotor material, damping structure and compressor. Breaking the comparison down this way shows value for money better than comparing headline prices.

Always confirm. A common practice is to quote the instrument without a rotor, or with one basic rotor only, with adapters and special rotors (microplate, decapping, blood bag) priced separately. Put your list of containers into the enquiry and ask for a quotation against it, so you do not discover after delivery that key accessories need a further budget.

The principle is describe the requirement, not a brand: use speed range and maximum g-force, capacity, temperature range, rotor types, safety functions (lid lock, imbalance and over-speed protection), calibration certificate and warranty period as the criteria, and avoid parameters only one supplier can meet. Do not set the ceiling unnecessarily high — over-specification raises the price and may attract no bids.

Three main items: consumables (tubes, adapter wear), maintenance (out-of-warranty repair, calibration) and downtime. On heavily used machines, rotor and seal replacement is a predictable expense; where there is no local service point, the cost of waiting for parts is often underestimated. Estimate total cost over five to eight years — closer to the real figure than price comparison alone.

The priorities are throughput, standardisation and freedom from error: blood tube decapping, serum separation, urine sediment and sample pre-treatment all need to be done in batches; programmes should be fixed rather than set by hand each shift; and the lid lock and imbalance protection must be reliable. A high-capacity model with decapping plus a benchtop high-speed unit for special assays is a common combination.

Large capacity, swing-out rotor, blood-bag cups, stable temperature control and traceability. Plasma separation must be carried out at the specified temperature and g-force, since batch-to-batch consistency directly affects component quality, and the equipment should log run parameters for traceability. A floor-standing refrigerated high-capacity model such as 6 × 2400 ml with a blood-bag rotor is a typical configuration.

The key is biosafety containment: prefer sealed cups or a biosafety rotor so samples are never exposed, site the instrument in a suitable area, and open it inside a safety cabinet. It must also handle high throughput for mass screening and be easy to disinfect, with chamber and rotor materials resistant to the usual disinfectants.

Focus on cleaning validation, material compatibility and traceable parameters: chamber and rotor must withstand the usual cleaning and disinfecting agents and resist residue build-up, and run parameters must be recorded and linked to the batch. In a GMP environment, equipment files, calibration and change control also apply. Clarifying large-volume culture broth usually calls for a high-capacity refrigerated model.

Start from the group's actual consumables and maximum g-force requirement: molecular biology work is mostly 1.5/2 ml high-speed plus 96-well plates; cell work needs refrigeration and a swing-out rotor; teaching demonstrations need simple operation and complete safety interlocks. For shared platforms, choose a model with interchangeable rotors and stored programmes to reduce setting errors between users.

Their pattern is varied samples, many methods and formal reports: pesticide residues, heavy-metal preparation, fat and protein determination, microbial enrichment — with containers from 50 ml tubes to homogeniser bags. A high-capacity refrigerated unit for main preparation plus a benchtop high-speed unit for micro-scale clean-up works well; store programmes under the method number for easy review.

Determination of water content in crude oil (distillation or centrifuge method) requires separation of oil and water at a constant temperature with the volume ratio read off. Temperature control and rotor symmetry are critical, the samples are viscous and special tubes are used. Dedicated models adapt the temperature control and tube positions to this application; substituting a general-purpose model tends to give biased readings.

Mainly solid–liquid separation of suspended solids and sludge, typically with larger volumes (hundreds of millilitres) and higher g-force, using large bottles. Requirements: sufficient capacity, adapters for large bottles, corrosion resistance (samples may be acidic or alkaline) and easy cleaning. Some methods have no temperature requirement, so an ambient high-capacity model is enough.

Samples are small and high-value, so contamination control comes first: micro-volume high speed (1.5/2 ml), a sealed rotor where possible, and easy disinfection. Cross-contamination between case samples must be avoided, with a dedicated instrument or rotor where necessary. Stable operation and reproducible parameters also matter for re-checking results.

Milk samples are used for composition and somatic cell counting and typically need medium capacity with temperature control; semen processing is sensitive to temperature and shear, requiring low speed, gentleness and accurate control. For both, a refrigerated benchtop model with a swing-out rotor and adjustable deceleration avoids damaging cells.