Dual temperature indicator

An improved critical temperature indicator of the type having a transparent capillary tube with a closed hollow bulb at one end and an open opposite end, said hollow bulb having a specified volume and said tube having a volume less than said bulb, a first liquid filling said bulb and extending into said tube, a separating means, and a second liquid located at said opposite end of said tube, said second liquid being separated from said first liquid by said separating means, said first liquid being miscible with said second liquid, said first liquid and said separating means having a combined volume being less than said bulb volume upon solidification of said first liquid, whereby said separating means and at least a portion of said second liquid are drawn into said bulb upon solidification of said first liquid to provide a first critical temperature indicator means, wherein the improvement comprises a second critical temperature indicator means and means to fix said second temperature indicator means to said tube opposite end, whereby said second liquid flows to aid open opposite end of said tube upon reaching a predetermined high temperature and whereby said second critical temperature indicator means is positioned adjacent said open opposite end of said tube for detecting and providing a visual indication caused by the expulsion of said second liquid out of said tube opposite end to said second critical temperature indicator means when said second liquid reaches said predetermined high temperature.

A dual temperature indicator providing visual indications at predetermined low and high temperatures comprising:

• a) a transparent capillary tube having a bulb and a tube end;
• b) said bulb having a specified bulb volume and said tube having a specified tube volume, said bulb volume being greater than said tube volume;
• c) a first liquid filling said bulb and extending into said tube and having the property of volume reduction upon solidification upon reaching a predetermined low temperature;
• d) a second liquid in said tube and being miscible with said first liquid, and having a solidification temperature lower than that of said first liquid;
• e) low temperature indicating means to provide a visual signal at said predetermined low temperature;
• f) separating means interposed between said first and second liquids for preventing mixing thereof within said tube, said first liquid and said separating means having a combined volume whereby upon solidification of said first liquid said combined volume is less than said bulb volume so that said separating means and at least a portion of said second liquid are drawn into said bulb upon solidification of said first liquid to provide said lower temperature visual indication signal at said predetermined low temperature;
• g) high temperature indicating means located at said tube end comprising absorbent visual signal means activatable at a predetermined high temperature;
• and
• h) means to fix said high temperature indicating means at said tube end, said first and second liquids and said separating means having combined volumes greater than the combined volumes of said tube and said bulb at said predetermined high temperature, whereby said second liquid is expelled from said tube end to said high temperature indicating means to provide a visual indication at said predetermined high temperature.