Gas-actuated thermometer

Abstract

The gas-actuated thermometer is formed as a unitary, monolithic glass structure with a gas bulb at one end and an indicator tube extending therefrom. The bulb and tube are permanently and hermetically sealed to contain the actuating gas therein. A closed cell foam indicator resides in the indicator tube. The indicator travels along the tube in accordance with the expansion and contraction of the gas within the bulb and adjacent portion of the tube. A second gas or mechanical spring is provided in the opposite end of the tube to balance the pressure of the indicator gas. The indicator tube, and preferably also the bulb, are flattened to an elliptical or similar cross-sectional shape. This facilitates the fit of the device for use as an oral medical thermometer, and the wider cross section enables both Celsius and Fahrenheit temperature scales to be marked along the indicator tube.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of my prior application Ser. No. 13 / 301,364, filed Nov. 21, 2011 now pending.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to instruments and devices for measuring temperature, and particularly to a gas-actuated thermometer containing an expandable gas volume therein that moves an indicator within the indicator tube as the temperature of the gas changes.[0004]2. Description of the Related Art[0005]The liquid-actuated thermometer, i.e., mercury filled, has been known for a considerable period of time. The use of the pure element mercury (Hg) in thermometers of various temperature ranges provides a number of advantages and conveniences. Pure mercury is a liquid at all ambient temperatures, from the hottest near-equatorial desert climates to winter polar temperatures. Mercury expands and contracts readily with temperature changes, thereby providing a ready indication of t...

AI Technical Summary

Problems solved by technology

Moreover, pure mercury is not particularly expensive to extract or refine, particularly in the relatively small amount required for the typical thermometer used to measure the ambient temperature or for medical use.

However, mercury is not without its problems and hazards.

While there is no hazard so long as the mercury remains completely enclosed in a hermetically sealed and unbroken container, the typical glass bulb and tube mercury thermometer is prone to breakage, and when such breakage occurs, the subsequent release of the mercury therein can prove extremely hazardous to individuals who might contact the released mercury, particularly if the thermometer is an oral thermometer that breaks in the mouth of the individual.

The conventional construction of the mercury thermometer, which includes a metal bulb (for better heat transfer) that is bonded to a glass column or tube, is also somewhat prone to leakage between the metal and glass interface.

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