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The central component of the Florida Museum of Natural History's Genetics Resource Repository is a liquid nitrogen freezer (model MVE 1830HE), located in Dickinson Hall on the University of Florida campus. It is designed to maintain temperatures below minus 300 degrees Fahrenheit. The freezer can store nearly 80,000 samples in 2-ml plastic vials.
The freezer is equipped with 54 racks arranged in six sections. Each rack holds 13 boxes of 100 vials. When the current configuration reaches capacity, the Museum plans to add 30 racks (designed to hold 25-cell boxes) to reach the freezer's largest capacity configuration. During regular operation, employees wear leather gloves and a protective face mask to minimize risks associated with handling liquid nitrogen and materials at cryogenic temperatures.
A small computer attached to the freezer uses a pressure sensor and two temperature probes to maintain the nitrogen level at a minimum of 5 inches. When the level drops below this setting, the computer opens a valve connecting the freezer to a liquid nitrogen tank. If liquid fails to flow from the tank, an alarm is triggered.
The freezer can hold 1,672 liters of nitrogen, but only requires 296 liters for the vapor level to maintain low temperatures. This volume keeps all storage racks above the liquid nitrogen. The rate of nitrogen consumption varies depending on how often the freezer is accessed. To reduce nitrogen use, the Museum processes loans and new accessions one day a week. At this access rate, the 180-liter tank must be replenished every eight to nine days.