Refrigeration that can be defended rather than merely cold: why a laboratory fridge freezer and a laboratory refrigerator freezer combo are chosen for temperature uniformity and alarm behaviour rather than for capacity, what a minus 80 degree freezer, an ultra low deep freezer and an ultra low temperature freezer price comparison leave out in heat rejection and service, why a domestic appliance is not an acceptable substitute for stored material that matters, what laboratory ovens at the other end of the range need in uniformity and calibration, and what monitoring has to record before a stored sample's history can be stated

Specifying refrigeration

1. Specify uniformity, not setpoint. A chamber whose shelves differ by several degrees stores some samples outside their condition. Ask for mapping data, and map your own unit once when it is installed and loaded.
2. Reject domestic appliances for stored material. They control by cycling around a setpoint and have no alarm or record. For anything with a stability claim or a replacement cost, that is not a saving.
3. Plan heat and power for very low temperature units. They reject substantial heat and draw power continuously. Several in one room raise the ambient temperature and shorten the life of all of them.
4. Monitor independently of the unit. A logger that records to a separate system survives the failure of the unit and produces the history you will be asked for. The unit's own display is not a record.
5. Calibrate ovens and incubators the same way. Heated equipment used for a process step needs uniformity mapping and calibration on a schedule, with the reference traceable.
6. Write and rehearse the transfer plan. Spare capacity, dry ice, a call list and a rehearsed procedure. A plan nobody has practised is discovered to be incomplete during the failure.

Uniformity is what a stability claim rests on

A reagent stored between two and eight degrees has to have been in that range, everywhere in the chamber, for the whole time. A unit that meets its setpoint at the sensor and not at the back of the bottom shelf does not satisfy that.

Map once, label the shelves with what can be stored where, and re-map after any change to the load or the room.

Alarms need a person

An alarm that sounds in an empty room at the weekend records the failure without preventing it. Escalation to a phone, with a named responder and a rehearsed action, is what makes monitoring useful.

Test the escalation, not only the alarm. Most monitoring systems fail at the human end of the chain.

Common questions

Why not use a domestic fridge?

Because it cycles its temperature by design, has no alarm and produces no record. For reagents with a stated storage condition, or samples that cannot be replaced, none of that is acceptable.

What does mapping involve?

Loggers placed through the loaded chamber over a period covering normal use, showing the range actually experienced. It takes a week and tells you which shelves can be used for what.

Should monitoring be part of the unit?

Independent monitoring is better, because it survives a controller failure and keeps a record the unit does not. Many units offer both and the independent record is the one that answers questions.

Browse by service class

• Compare Gene synthesis on advertised prices