Abstract: A tertiary heat exchanger having three sets of adjacent ducting, two stacked within the third, all of which carrying heat exchange mediums so that the heat carried by one medium in any set of a ducting is efficiently transferred to the other two. Two of the three sets of ducting are tubing and this tubing is spirally coiled in a container within the third set of ducting. The two sets of tubing are in alternating layers and the fluid flow of the heat exchange mediums are in opposite directions in each adjacent layer of the tubing. Outlet channels are provided at various points along the helical path of a ducting so as to alter the effective length of a ducting.

Abstract: A method of bonding powdered material to a surface comprising placing at least one layer of powdered material onto a support of ductile material, positioning a surface to be coated by the powdered material in facing spaced relation with the powdered material and placing an explosive charge on the support on the surface thereof opposite the powdered material. The explosive charge is then detonated to produce acceleration of the support and the powdered material thereon towards the surface to be coated to cause impact of the powdered material with the surface to be coated and welding thereof. The detonation of the explosive charge proceeds along the length of the charge to progressively bring the powdered material into impact contact with the surface to be coated. The speed of detonation of the explosive charge is less than the speed of sound in the powdered material or support.

Abstract: A metal wall, such as that of a vessel, is provided with cladding which is welded to the metal wall such that an elongated space is formed between the weld seams. The elongated space allows for the testing of the weld seams for leakproofness by closing off one end of the space and injecting a gaseous medium, or the like, into the space and gauging whether or not the medium exits via the weld seams. A plate made of rubber, plastic or the like may also be used in welding the cladding to the metal wall, which plate covers the unconnected ends of the two cladding parts making up the cladding layer for the metal wall.

Abstract: A file for holding perforated sheets is provided adjacent its spine with a pair of spaced apart tubular prongs for cooperation with the sheet perforations. The file is provided at its spine with a leaf spring of which a portion protruding from the inner side of the spine, in the position of use of the file, abuts against the web of a substantially U-shaped wire member, the arms of which engage the tubular prongs to retain the sheets to the tubular prongs. The leaf spring portion protruding from the spine to cooperate with the web of the U-shaped wire member has a tongue integral with the protruding leaf spring portion and directed towards the spine of the file. When the protruding leaf spring portion is caused to abut against the web of the U-shaped wire member, the tongue snaps home under the wire to lock the leaf spring to the U-shaped wire member.

Abstract: A cord winder arrangement particularly for a vacuum cleaner or other household appliance in which the vacuum cleaner housing is provided with a section having a closable access door through which the cord and the electrical connection plug passes through when the vacuum cleaner is inoperative, thereby enclosing the electrical cord and its plug entirely within the vacuum cleaner housing. The access door is operated by a foot button that opens the door and, at the same time, projects the plug out of the housing when it is desired to operate the appliance.