Temperature rise detectors for frozen food pack or chambers - involving use of fragile or porous glass or plastic vessels contg. liq. dye

摘要

A device for detecting a rise in temp. after an initial freezing treatment comprises a fragile container of glass or plastic (rigid PVC) contg. a dyed liq. which will burst the container upon being frozen and therefore will spread irreversibly if the temp. subsequently rises above the m.pt. of the liq. Used esp. for checking if the temp. of deep frozen food etc. has risen above about-15 degrees C prior to being required for use, by using an aq. soln. contg. a freezing pt. depressant (such as iodine) and a dye (such as eosine). Instead of a fragile tube or capsule, the 'container' may be porous sponge from which the dyed liq. can drain freely when melted. Detectors with a vol, of about 1 ml may be used in individual packages or laid in a freezer compartment to signal a temporary rise in temp. even if the temp. is subsequently again reduced to below -15 degrees C.