GB409306A - Improvements in or relating to hot-water bottles and like containers for heating-fluid - Google Patents

Abstract

409,306. Heating hot-water bottles by electricity. NORRIS, G. THORNTON-, 197, Lauderdale Mansions, Maida Vale, London. Oct. 25, 1932, No. 29859. [Class 39 (iii).] An electric heater for a hot-water bottle comprises a closure member 10 forming part of the wall 12 of the bottle and carrying a heating element 18, a thermostatically operated switch 21 and a current controlling means 23 operated by gravity so that current passes when the heater is directed upwardly into the liquid space, the thermostatic switch 21 being isolated from the heating element 18 except for heat transmitted through the liquid. The heating element is a wire-wound strip in a flat tube bent as shown with its ends entering the hollow metal closure member and connected to a plug 34. The gravity switch comprises a bulb 23 containing electrodes 50, 51 at one end, and a contactmaking element 49, e.g. a drop of mercury. The thermostatic switch may comprise a delayed-action bimetallic strip 44 with a deadcentre spring 47 as set out in Specification 222,535, [Class 38 (v)]. A further safety plug 22 comprises a bulb with a plug of fusible material 54 normally bridging electrodes 52, 53, one of which is insulated except at its tip, the material when molten running back to break the contact. The three controlling means are placed in a metal casing 17. The flexible hot water bottle may be stiffened round the closure member and held extended by a telescopic arm on an electricity supply plug. The flexible water container may be applied to medical purposes, e.g. operation tables or water beds, or the container may be rigid. The current may be automatically cut off or'reduced when a certain temperature has been reached.