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US 7,011,445 B1Granted
Maximum/minimum thermometer
AssigneeS. Brannan & Sons, Ltd.
InventorsJohn Montgomery Hamilton, Peter Graham Perkins
Life of this patent
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Abstract
This invention relates to maximum/minimum thermometer of the type comprising an expansion liquid, a transfer liquid and indexes for recording the maximum and minimum temperatures. Described in particular are new transfer liquids designed to replace conventionally used mercury and new indexes suitable for use in the disclosed thermometers.
Claims17
A reusable maximum/minimum thermometer comprising
- an expansion liquid (42) which expands or contracts in response to changes in temperature,
- a transfer liquid (48) which is moved in response to the expansion or contraction of the expansion liquid and which is substantially immiscible with the expansion liquid,
- two indexes (44, 51), and
- a temperature scale associated with the maximum/minimum thermometer, wherein the indexes are constructed from a plastic material into which has been mixed and/or melted a quantity of magnetic powder such as iron filings, magnetite (Fe3O4), and/or strontium ferrite, and wherein the indexes have a density less than that of the transfer liquid, are able to float on the surface of the transfer liquid, and are moved by the transfer liquid into resting positions whereby maximum and minimum temperatures are read off the temperature scale, and
- wherein the transfer liquid is a mercury free solution selected from the group consisting of inorganic compounds, organometallic compounds, organic liquids, and ionic liquids.
2 more elements
Dependencies are inferred from the claim text.