Abstract

A cryogenic storage device includes a storage tank having an inner tank, an intermediate tank and an outer tank spaced apart from each other so as to define a fluid reservoir for holding a cryogenic liquid and a thermal insulative space bounding the fluid reservoir. A top cover closes the open top. An inlet supplies the cryogenic liquid to the fluid reservoir. A fluid sensor is configured to detect a pressure within the cryogenic storage device and is removably disposed within the fluid reservoir so as to allow an ice formation to be thawed without having to thaw the entire cryogenic storage device.