A lab freezer is not just a bigger freezer than the one people use in their own homes, it's a specific device used to keep critical materials, many of them dangerous, at a constant, regulated temperature. They can be small enough to fit beneath a counter, the size of a normal upright freezer, or even as large as walk in freezers. While most household freezers are kept between zero and -10 degrees Celsius, a lab freezer can get as low as -85 degrees Celsius.
These freezers are used for a variety of purposes, such as storing serums and tissue samples, bacteria strains, samples of RNA and DNA, and protein extracts. In hospitals they can be used to preserve organs and blood, and in pharmacies to keep medicines. As many of these specimens can degrade over time, it is important to keep them preserved and stable.
A general purpose laboratory freezer can look very similar to a home refrigeration unit. Much like a home refrigerator, they have shelves both in the unit and in the door, as well as rubber gaskets to prevent the cold from escaping. However, these freezers keep the temperature between -15 to -25 degrees Celsius. They can be locked, and come with an LCD temperature display to allow you to keep an eye on the temperature without having to open the lab freezer to check.
Low temperature freezers, such as the Harris Super Insulated freezer, can store 31.4 cubit feet, and allow almost 70,000 samples in 35 inventory racks, and can reach temperatures as low as -86 degrees Celsius. There are also super low lab freezers, such as the Thermo Scientific cold storage freezer, which can reach astonishing cryogenic temperatures of -150 degrees Celsius without having to utilize liquid nitrogen.
For the storage of flammable materials, a lab freezer is a must. There are freezers specially designed for the safe storage of volatile materials that have CFC free, foamed-in-place insulation and hermetically sealed compressors. These products meet OSHA standards, but you should still make certain to have alarms, monitors, and backup performance features if you are freezing critical biologicals or high-value life science materials.
An important freezer product is the blood bank freezer, used for storing blood and plasma. An ordinary refrigeration unit is not able to properly maintain the delicate balance of temperature, especially during the intervals when a door may be opened. Blood bank freezers must be durable and, due to their importance in saving lives, require very little maintenance as blood has a very brief shelf life. These freezers, as with many lab freezers, come with both monitoring systems and automatic warning systems.
There are many varieties of lab freezers available, including liquid nitrogen freezers that can reach temperatures as low as -190 to -196 degrees Celsius. You can also find mini-room walk-in freezers which allow for almost 1,000 cubic feet of storage, though they do not generally reach the same extremes in temperature.
When looking at lab freezers, you should consider what you will be keeping inside. The more delicate or dangerous the sample, the more attention it will need. You can find lab freezer accessories such as recorders, CO2 and LN2 backup systems, thermometers and alarm systems to help you keep track of the temperatures. A laboratory freezer is a vital part of any science lab, and if taken care of will last for years.
