Abstract: A flexible thermal insulation panel in the form of a block of consolidated particulate microporous insulation material enclosed in a porous envelope. The block is bonded to the envelope by compression of the envelope to cause penetration of particles of insulation material at the surface of the block into pores of the envelope. The envelope comprises a stretchable material, at least in part. The consolidated block and the stretchable material of the envelope bonded thereto can be conformed to a non-planar surface with the stretchable material of the envelope remaining bonded to the block.

Abstract: At least one edge of a substantially planar panel of microporous thermal insulation material is shaped by first restraining the planar faces of the panel so as to resist deformation of the faces of the panel adjacent to the edge of the panel to be shaped. A forming member is then urged against the edge of the panel so as to shape the edge, the forming member being profiled such as to cause the edge of the panel to be recessed. The forming member is then removed from the edge of the panel so as to permit the panel to adopt a relatively square edge, and the planar faces of the panel are released.

Abstract: A non-planar formed body of particulate insulating material is made by first compacting substantially inorganic non-fusible particulate insulating material to form a plane panel. Covering material such as glass cloth coated with a settable composition or thermoplastic material effectively comprising a settable composition, is disposed adjacent one or both faces of the plane panel, in a mould. The mould is then operated to form the panel into the desired non-planar form, and the settable composition is allowed to harden.

Abstract: A coiled heating element is manufactured by providing a coiled element of bare resistance wire in which the coil pitch is not greater than twice the cross-sectional dimension of the wire. The element is stretched by an amount permitting recovery to its original configuration and an electrically insulating particulate material is applied to the stretched element. The stretched element is then allowed to return towards its original configuration thus trapping particulate material between adjacent coils of the element and the element is heated so as to oxidize the surface of the wire.

Abstract: A method of manufacturing a microporous thermally insulating body comprises mixing together a finely divided microporous insulating material such as silica aerogel or pyrogenic silica and a solid ammonia-generating compound in particulate form, and compressing the mixture to form a thermally insulating body. The ammonia-generating compound is dispersed evenly throughout the insulating material and may comprise, for example, ammonium carbonate, ammonium acetate or urea. Preferably, the ammonia-generating compound comprises a mixture of about one third by weight of ammonium carbonate and about two thirds by weight of ammonium bicarbonate together with a small proportion of magnesium oxide.

Abstract: An electric heater assembly for a glass ceramic top cooker includes a plurality of electric heating elements, a thermal cut-out device incorporating a first set of contacts for controlling the supply of electric current to at least one of the heating elements, and a relay associated with the thermal cut-out device and incorporating a second set of contacts for controlling the supply of electric current to at least another of the heating elements. In the event of the thermal cut-out device detecting a first predetermined temperature the first set of contacts moves from a first position to a second position causing the second set of contacts to move from a first position to a second position and in co-operation with the second set of contacts connects the heating elements in a lower power configuration or cuts off the supply of electric power to the heating elements.

Abstract: A radiant electric heater assembly for a glass ceramic top cooker includes four radiant electric heating elements and a thermal cut-out device. Associated with the termal cut-out device is a switching device for connecting the four heating elements in parallel with each other to give a first power level setting and for connecting the heating elements in a lower power configuration in which the elements are connected as two elements connected in series with each other and connected in series with a pair of elements connected in parallel with each other. When the thermal cut-out device detects a first predetermined temperature the heating elements are connected in the lower power configuration until such time as the thermal cut-out device detects a second predetermined temperature, lower than the first predetermined temperature, when the heating elements are reconnected in the configuration of the first power level setting.

Abstract: A power control arrangement for controlling the power output of a plurality of resistive heating elements (9a, 9b) comprises a multi-position switch (S1, S2) for connecting the heating elements in series and in parallel, a zero voltage switch (4), AND-gate (5), clock pulse generator (6), shift register (7) and semiconductor device (8) such as a trail which cooperate to vary the duty cycle applied to the heating elements in both serial and parallel modes.

Abstract: A fire-resistant container for magnetic media is constructed by mounting a base of thermal insulation material within a casing having an open face and by positioning on the base and securing to the base a body of thermal insulation material so as to define with the base a cavity which is open towards the open face of the casing. An inner container is positioned within the cavity so as to have an opening towards the open face of the casing and has an inner wall defining a storage cavity and an outer wall which defines a chamber filled with heat absorbing material between the inner and outer walls. A storage drawer is inserted into the storage cavity and has attached thereto a container located on that side of the drawer adjacent to the opening, the container being filled with a heat absorbing material. A layer of thermal insulation material is positioned on that side of the container remote from the drawer and a facing is located on that side of the layer of insulation material remote from the container.

Abstract: An electric heater for a glass ceramic top cooker includes a base layer of thermal insulation material such as ceramic fiber or a microporous thermal insulation, a source of infra-red radiation such as a pair of infra-red lamps, and a reflector which is positioned so as to reflect infra-red radiation emitted by the source towards the layer of thermal insulation material. The reflector may be a specular reflector such as a coating of a reflecting metal deposited internally or externally of the source of infra-red radiation or may be a diffuse reflector such as a layer of fine particulate alumina deposited onto the external surface of the source of infra-red radiation.

Abstract: Shaped pieces of insulation having non-uniform thickness but substantially uniform density are formed by simultaneously compacting and consolidating at least first and second portions of a particulate insulation material in an independent manner so as to form a shaped piece of insulation in which the first and second portions have different thicknesses in the direction of compaction. The degree of compaction of the first portion is the same as the degree of compaction of the second portion so that the shaped piece of insulation has substantially uniform density.

Abstract: A panel of microporous thermal insulation material is manufactured by applying a film of polyvinyl acetate emulsion to a non-porous substrate, such as a sheet of steel, and compacting powdery microporous thermal insulation material against the film so as to cause the consolidated insulation material to bond to the substrate and form a panel.

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 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.