Second hand instruments are the cheapest capacity a laboratory can buy and the easiest way to acquire an expensive ornament. The difference is almost always support rather than condition: a machine whose maker still sells parts, still services the model and whose software runs on a supported operating system can be maintained, and one whose control system is orphaned cannot be, however well it was looked after.
Lab benches for sale, and what to measure first
Benching is the cheapest thing on a used market and the most often bought in the wrong size. Measure the room before the bargain: service runs and where they enter, knee space and seated height for the work, depth against the door and corridor it has to come through, and the top's material against the chemistry, since epoxy resin, stainless, phenolic and laminate tolerate very different things. Check that fume hood and cabinet positions are not blocked, and that the floor loading suits a stone or steel top.
used imaging equipment and used inspection equipment, and what to ask
Optical and inspection instruments survive well, and the questions are about the parts that wear: the light source and its hours, the stage and focus mechanics, the camera and whether its driver still runs, and for anything with a vacuum or a laser, the service history of that subsystem. Ask for a sample image or a measurement on a known artefact rather than a photograph of the instrument. Then ask who will move and reinstall it, since alignment rarely survives a careless journey.
A used microplate reader, and what decides its value
A reader's value is in its detection modes and its software licence. Absorbance-only instruments are cheap and adequate for ELISA work; fluorescence, luminescence and time-resolved options each add cost and each needs to be tested on the seller's bench with a real plate. Check the lamp or LED hours, the filter or monochromator condition, and above all whether the acquisition software transfers with a licence and runs on an operating system your institution still allows on a network.
A viscometer for sale and a cryostat for sale, and their own checks
A viscometer is a calibration question: the geometry set, the temperature control and whether it can be verified against a certified viscosity standard, since a reading that cannot be traced is not a measurement. A cryostat is a mechanical and a safety question: the compressor and its refrigerant, the blade holder and anti-roll plate, the chamber's frost and seal condition, and the decontamination history, because a second hand cryostat has cut somebody else's samples and the disinfection record matters.
A used gc ms and a used mass spectrometer, and the support question
Coupled systems are the highest-value and highest-risk purchases on the used market. Ask for the pump hours and service records, the source condition and when it was last cleaned, a performance report on a standard mixture run in front of you or shared as raw data, and, decisively, whether the data system's licence transfers and is supported on a current operating system. Decommissioning, moving and reinstalling one is specialist work, and its cost belongs in the comparison with a new instrument.
Where support ends, and how to find out before buying
Every maker publishes, or will tell you, when a model left production and how long parts and service continue after that. Ask directly, in writing, for the model and serial number in front of you: whether a service contract is available, what parts are still stocked, and whether the software is supported. A refurbisher's warranty is worth having and is not a substitute for that answer, because the refurbisher cannot manufacture a board the maker has discontinued.
What a refurbishment should include
Refurbished is a claim rather than a standard, so ask what was done: wear parts replaced, interlocks and safety systems tested, calibration verified against a reference with a certificate, consumable paths cleaned or renewed, and a warranty with a named service route. For anything with a rotor, a laser or a pressure vessel, the component's own life record matters more than the instrument's appearance, since those retire on use rather than on condition.
Qualification after installation, and why it is not optional
A used instrument arrives with no installation qualification, so the first work is to establish that it performs where it now stands: a documented installation and operational check against the maker's specification, a calibration where a reading enters a result, and, for a regulated laboratory, a performance qualification on the methods it will run. Budget that work with the purchase. An instrument that cannot be qualified is not cheaper than a new one, it is unusable.
Questions people ask about used liquid handlers
What is the single most important question?
Whether the maker still supports the model with parts, service and software on a current operating system. Condition is recoverable; an orphaned control system is not.
Is a refurbisher's warranty enough?
It is worth having and it cannot replace parts the maker has discontinued. Ask the maker about support for that exact model and serial number.
What is usually forgotten in the budget?
Decommissioning, moving, reinstallation and the installation and operational qualification the instrument needs where it now stands.