Improvements in and relating to Electric Fire Alarms and Thermo-indicators.


12,379. Hawthorn, H. May 30. Alarms, fire and temperature.-Two closed tubes a, b, filled with fluids and mounted on opposite sides of an insulating-stand c, have contact points f, g so connected to their free ends that, when the tubes expand with heat, according to the Bourdon principle, the contact points are moved in a straight line. One tube is made slower acting than the other, by having thicker metal walls, or a non- conducting or other coat, or by being filled with a different liquid. On a sudden rise of temperature, the screw contact f of the more sensitive tube catches up the other point g and completes a circuit, which may be made to indicate the particular apparatus affected. The tubes are, preferably, nearly circular in shape, or they are made into a spiral or helix. The tubes are pivoted at j, k to arms d, e flexibly joined to nuts h, i on the base c. The apparatus may be placed in a casing l perforated to admit air, and means may be provided to lock the points f, g when they come into contact.




Download Full PDF Version (Non-Commercial Use)

Patent Citations (0)

    Publication numberPublication dateAssigneeTitle

NO-Patent Citations (0)


Cited By (0)

    Publication numberPublication dateAssigneeTitle