Abstract: An object such as a fuse is enclosed within a homogeneous block of microporous thermal insulation material by a method which includes forming first and second blocks of insulation material having a relatively low density, arranging the object between co-operating faces of the blocks, and compacting the blocks around the object so as to cause the blocks to merge and to form a homogeneous block of microporous thermal insulation material having a relatively high density. The first and second blocks may be incorporated into first and second housings respectively, one of the housings being provided with a protruding tab and the other of the housings being provided with a corresponding slot.

Abstract: An infra-red heater (1) for a glass ceramic top cooker includes a dish containing a base layer of thermal insulating material. A peripheral wall of thermal insulating material extends around the periphery of the base layer and at least one infra-red lamp (3) extends across the base layer. A ballast device (5) is electrically connected in series with the infra-red lamp, for example in the form of a coil of bare resistance wire, and serves to reduce inrush current to the lamp. A thermal cut-out device (7) cuts off the supply of power to the infra-red lamp and to the ballast device (5) if the temperature of the glass ceramic cooking surface becomes excessive. The coil of bare resistance wire preferably has an electrical resistance which is approximately half the electrical resistance of the infra-red lamp at its operating temperature. The use of a ballast device (5) enables the infra-red lamp (3) to be used in conjunction with a cyclic energy regulator (9).

Abstract: A method of enclosing an object, such as an electronic component, within a homogeneous block of microporous thermal insulation material comprises charging a first predetermined amount of a loose microporous thermal insulation mixture into a die and compacting the insulation mixture into a block for supporting the object to be insulated. A recess may be formed in the compacted mixture for receiving the object. The object is then located on the compacted mixture and a second predetermined amount of loose microporous thermal insulation mixture is charged into the die. The loose insulation mixture is compacted against the block of already compacted insulation material which causes the two charges of insulation mixture to merge and to form a homogeneous block enclosing the object.

Abstract: An electric radiation heater assembly for a glass ceramic top cooker includes at least one heating element having a substantial positive temperature coefficient of resistance, such as an infra-red lamp. A resistive assembly is electrically connected in series with the at least one heating element for suppressing surges of electric current due to the low initial resistance of the heating element. Switch means is operable a time interval of at least thirty milliseconds and preferably about 1/2 second after a supply of electric power to the heater is energized so as to reduce the combined electrical resistance of the heating element and the resistive assembly.

Abstract: A vessel for holding high temperature bulk materials, such as a ladle for handling molten metal, includes a steel bucket containing a permanent outer layer of refractory material. Within the outer layer is an expendable layer which is made up from relatively rigid boards of compacted microporous thermal insulation material. Within the layer of microporous thermal insulation material is a further expendable layer of refractory material which covers the inner surface of the layer of microporous thermal insulation material. The thermal capacity of the expendable layer of refractory material is preferably less than the thermal capacity of the permanent outer layer of refractory material.

Abstract: A panel of microporous thermal insulation which comprises an envelope of glass fibre cloth which surrounds and is bonded to a block of microporous thermal insulation is manufactured by heating the glass fibre cloth so as to drive off organic material, applying a silane in an acidic solution to the cloth, drying the cloth in order to produce cross-linking of the silane so as to cause the cloth to stiffen, and applying to the cloth an aqueous suspension of particulate silica, an aqueous solution of sodium silicate or potassium silicate, or a cellulose solution. Microporous thermal insulation is introduced into a bag mode from the cloth and the bag is then compressed to consolidate the insulating material and to produce a bond between the insulating material and the bag.

Abstract: A radiant electric heater has a support which bears a layer of microporous thermal insulation material such as that sold under the registered trademark "Microtherm" with a heat transmissive cover spaced from the layer by a peripheral wall and heating elements positioned within an area defined by the peripheral wall and coiled around a plurality of quartz tubes. The quartz rods are urged against the layer of microporous thermal insulation material by the cover by way of the peripheral wall.

Abstract: A fire-resistant container for protecting magnetic media such as floppy discs comprises a base and a cover. The base is in the form of an outer casing and an inner container separated by thermal insulation material which is maintained under compressive stress so as to retain the inner container in position within the outer casing and to permit the insulation material to expand when the outer casing expands as a result of exposure to high temperature. The inner container may have a hollow wall which is filled with wax. The cover may comprise a dished outer cover, an inner cover and thermal insulation material which is maintained under compressive stress.

Abstract: Tubes of microporous thermal insulation material are manufactured by compacting microporous material to a slab having a density of about 150-400 Kg/m.sup.3 and a thickness of about 1-5 mm, applying to one surface of the slab a membrane, for example of self-adhesive aluminum foil, wrapping the slab around a mandrel so that the ends of the slab abut substantially against each other, and securing the ends of the slab relative to each other, for example by means of a protruding flap of aluminum foil.

Abstract: A thermal cut-out device for a radiant heater includes a probe-type thermally responsive assembly (2), at least a part of which is coated with and/or is surrounded by a radiation reflective material. The probe-type assembly may include a first element (3) in the form of a rod of material having a relatively high coefficient of thermal expansion and a second element (4) in the form of a tube of material having a relatively low coefficient of thermal expansion. The rod may be coupled to a snap-acting switch assembly (1). One or both of the first and second elements may be coated with or surrounded by the radiation reflective material. Alternatively the tube which surrounds the first element may be made of the radiation reflective material. The radiation reflective material may be a metal such as gold or a suitable element from Group VIII of the Periodic Table or may be a high temperature resistant particulate material such as aluminium oxide, magnesium oxide, titanium dioxide or tin oxide.

Abstract: Handleable and machineable shapes of thermal insulation material are made by compacting finely divided thermal insulation material into the cells of a reinforcing honeycomb structure.The finely divided thermal insulation material may be, for example, silica aerogel, pyrogenic silica, carbon black, silica gel, volatilized silica, calcium silicate, vermiculite or perlite, or finely divided metal oxides such as alumina or titania. The finely divided thermal insulation material may include an infra-red opacifier and/or reinforcing fibres.The reinforcing honeycomb structure may be made from, for example, metals such as aluminium foil, inorganic materials such as ceramics, organic materials such as plastics materials, woven fabrics or paper. A rigidiser may be employed.The shapes of thermal insulation material are substantially rigid and may be machined, for example, by mechanical or laser cutting devices, or may be formed, for example by rolling, into curved or other shaped materials.

Abstract: A panel of thermal insulation material has at least one main panel portion which comprises a dry particulate insulation material compressed within a porous envelope so that it is rigid or substantially rigid and at least one auxiliary panel portion which is secured to and extends along at least one of the edges of the or each of the main panel portions. The or each auxiliary panel portion comprises a substantially uncompressed dry particulate insulation material contained within an envelope. The insulation material of the auxiliary panel portion may be the same as or may be different from the insulation material of the main panel portion. The envelope of the auxiliary panel portion may be made of a porous or a non-porous material.

Abstract: Panels are secured to a substantially flat or convex surface by means of hooks which are attached to the surface at opposite ends of a panel. The hooks are dimensioned so as to terminate at a level beneath the level of the outer surface of the panel and a band of fabric material is positioned on each of the hooks by means of a loop formed substantially at the mid-point of the band, the band also having a loop at each end thereof. The panel is secured to the flat or convex surface by means of springs which are attached to the free ends of the bands and by means of a strap which extends between the springs.

Abstract: An electric cooker having means for warning the user when one or more of the cooking surfaces is above a safe touching temperature comprises a glass ceramic cooking surface having one or more electrical heaters arranged on the underside of the cooking surface. A temperature monitoring device is thermally coupled with at least one of the one or more heaters and comprises an auxiliary heater, for example of PTC material, a thermally responsive device in the form of a thermistor, for example of PTC or NTC material, and a thermal buffer positioned between the auxiliary heater and the thermistor. A neon lamp or a filament lamp is provided for indicating when the thermistor is at or above a predetermined temperature.

Abstract: An electric radiant heater unit of the kind used in glass ceramic top cookers comprises first and second heater elements disposed adjacent to each other on a base layer of thermal and electrical insulating material, the arrangement being such that, in use, the heat emitted by the second heater element augments the heat emitted by the first heater element. A peripheral wall of thermal insulating material surrounds the heater elements and a thermal cut-out device extends over both of the heater elements. There is also provided means such as a block of thermal insulating material or a heat sink for shielding the thermal cut-out device in the regions thereof which pass over the second heater element from heat emitted by both the first and second heater elements.

Abstract: An energy regulator for a household heating appliance such as an electric cooker comprises an electronic controller for the cyclical control of the supply of electrical energy to a heating element and a switch for increasing the electrical energy supplied to the heating element to a preselected level and for a preselected time. The preselected time may be variable in dependence on the duty cycle of the controller, the duration decreasing from about thirteen minutes at low duty cycle to one minute or less at high duty cycle. Actuation of the switch may cause the electrical energy to be increased to substantially 30% of full heating power at low duty cycle rising to substantially 100% of full heating power at high duty cycle.

Abstract: A glass ceramic top cooker has at least one radiant heater arranged beneath the glass ceramic surface, the or each radiant heater comprising a continuous base layer of electrical and thermal insulating material, a peripheral wall also of electrical and thermal insulating material, and a heating element arranged on the base layer. The radiant heater also includes means, such as a pad, disposed on the base layer for isolating a region within the peripheral wall from heat emitted by the heating element and a temperature sensor, such as a thermocouple or a platinum resistance, mounted within the isolated region so as to be sensitive in use substantially only to the temperature of a cooking pan which is heated by the heater. The temperature sensor is effective because there is created on the glass ceramic plate a cold patch through which the temperature of the pan can be determined.

Abstract: An electric radiant heater unit for a glass ceramic top cooker comprises two independently energizable heater elements supported on a base of electrical and thermal insulation material. A thermal cut-out device, which may be of the differential expansion type, extends from a peripheral wall of the unit across one element and across a zone normally occupied by at least a part of the other element. However, that zone of the heater unit heated by said one element is extended to influence substantially the entire effective length of the cut-out device, that is including that portion of the cut-out device which extends across the zone normally occupied by at least a part of the other element.

Abstract: An electric radiant heater unit for a glass ceramic top cooker includes an inner circular heating coil and an outer annular coil surrounding the circular coil. The two coils are separated by a dividing wall of thermal insulating material and the annular coil is surrounded by a peripheral wall of thermal insulating material. The inner coil may be energized alone or both coils may be energized together. The electrical resistance of the inner and outer coils is such that the watts density within the peripheral wall when both coils are energized is greater than the watts density within the dividing wall when only the inner coil is energized.

Abstract: A glass ceramic hob electric cooker is provided on each of the radiant heaters thereof with a temperature responsive element such as a bi-metallic switch or a thermistor, which element is arranged adjacent to or within an opening which communicates with an enclosed chamber formed between the heater and the underside of the glass ceramic cooking surface. When the heating element of the heater is energized, hot air issues from the opening and impinges on the temperature responsive element thus heating said element. A warning lamp is connected with the temperature responsive element to indicate when said element and thus the glass ceramic cooking surface is at or above a safe touching temperature of 50.degree. to 60.degree. C.