GB889047A - Improvements in and relating to liquid heating apparatus - Google Patents

Abstract

889,047. Immersion heaters. GILL Ltd., R. T., and GILL, R. T. May 10, 1960 [May 12, 1959], No. 16306/59. Class 39(3) Apparatus for heating liquids comprises an electrical heating element movable relative to a liquid container but not supported by the container and a switching device for switching off current supplied thereto. The heating element is mounted on a movable, preferably flexible arm 12 and is used to measure energy, temperature or time lapse. 16 is an on and off switch and is held on against a spring by relay 17. A temperature sensitive resistance R 2 is in the bridge circuit R 2 , R 3 , R 4 , R 5 . When R 2 alters due to heating the spring moves the switch 16 to the off position. Neon indicators show whether the switch 16 is on or off. Alternatively a mechanical timing switch of double pole clockwork operated type is connected in series with the mains alone or in parallel with another type of automatic switch for alternative operation or controls switch 16. If the heating element has a tapped winding a selector switch is connected in circuit to provide for increased or reduced heating rates. Circuits may prevent operation if the earth connection to the heating element is disconnected. The circuit heats jugs, pans such as saucepans, teapots of translucent plastic. The containers may have an entrance duct for liquid at the bottom of the vessel controlled by an adjustable flow valve and a flow restricting exit duct. A clockwork or electric time switch or a thermostat or a thermoelectric time delay switch or a bimetal switch may be used and may be in the plug for the heating element, Fig. 1 (not shown). In another embodiment, Fig. 3 (not shown) a flexible or rigid arm or an arm of rigid members pivoted together holds the heating element. The heating element may be formed by winding high resistance wire on to one or more mica former strips and bending the arrangement round an open ended metal cylinder inside an outer metal cylinder. The windings of the heater are packed with "pyruma" (Registered Trade Mark). The outer casing is a rectangular strip of light gauze metal provided at one end with three metal tongues wrapped around. The tongues are welded or soldered to the other end of the strip. The ends of the cylinders are joined by soldering or welding. An earthing lead (preferably duplicated) formed by metal braiding or screening for the cable is connected to the inner and outer metal cylinder. The cable passes into the supporting arm. In another embodiment, a conductive perforated earthed stainless steel mesh screen is disposed close to the heater. The position of the arm operates a safety switch. In all embodiments, variations in the heating rate are obtained by tappings on the resistance wire of the element so that parts of the wire can be switched in or out as desired. The liquid may have suspended solids and fine grain solids in motion.