Cold-storage solutions for costly laboratory samples are not found at a local appliance store, but instead are the result of careful purchasing decisions based on the value of the products being stored. The price of poor laboratory refrigeration was dramatically demonstrated in a December 4, 2007, USA Today article reporting that it accounts for a big part of the $20 million in waste incurred by the federal Vaccines for Children program.
But decisions don’t end with an agreement to invest in high-quality laboratory refrigerators to store precious samples under development or vaccinations against diseases. Indeed, the ability of a unit to maintain consistent controlled temperatures is a paramount purchasing decision. That is because sometimes even small fluctuations in temperature can have unfortunate consequences.
Understanding the Differences between Lab Refrigerators
As with residential and commercial refrigeration units, laboratory-grade units are offered with manual and automatic defrost options. While there are conveniences associated with auto-defrost refrigerators, there is also a cost penalty in that they use more electricity for the condenser and for the constantly running fans that prevent icing of the condenser. This air circulation can also cause samples to dry out unless they are protected in sealed containers. Options on these units allow lab technicians to program the duration and frequency of the defrost cycle. Refrigerators equipped for auto defrost are commonly used to store products unaffected by minor temperature fluctuations during defrosting cycle, which typically takes about 15 minutes.
Manual defrost refrigerators are not equipped with cycling condensers or fans. Refrigerant circulates through copper tubing in the walls – providing a “cold wall” that causes moisture to condense and pool at the bottom of the cabinet. While these units provide lab technicians with full control over the defrosting cycle, temperature-critical contents should be relocated to other storage units during the defrosting operation. Condensate water that pools at the bottom of the unit can be removed when units are equipped with a defrost drain.
Other purchase criteria can include security (locking), fast temperature recovery and a temperature fluctuation alarm system.
Which do you prefer – Manual or Automatic Defrost – and why?