Abstract: The novel inductor is used in a glass fiber manufacturing equipment comprising a centrifuge heated by a main gas heating device and a complementary induction heating device. The efficiency of the inductor is increased by a magnetic flow guiding element disposed between the inductor and the main heating device. The invention is particularly adapted to be used in the manufacture of glass wool.

Abstract: The static converter of the invention comprises a central processor (15) measuring the output voltage (TM3), the output current (TM4), the rectifier current (S) and the reverse bias time (8) of the thyristors of the switch (5). From this information it drives, through interfaces (17, 18, 20) the starting thyristors (6) comprising a series resonating circuit intitiating the oscillations of the parallel resonant load circuit (2,3).

Abstract: A device is provided for melting by direct induction substances which are dielectric when cold and whose temperatures of inductibility and melting are close to each other, such as glasses or vitreous enamels. This melting is carried out inside a receptacle whose sidewall comprises a multi-turn inductor made from metal tubing whose inward-looking faces are exposed and which combines the functions of heating the charge by induction and cooling the periphery thereof. Such a receptacle which is at the same time a heating inductor and a cooling surface is applicable more especially to industrial electric furnaces for the production of molten glass or enamel by direct induction.

Abstract: A direct induction furnace or device for melting a charge held in a cold sheath or shroud with electromagnetic confinement of the conducting portions of the charge. The cold shroud comprises a cylindrical sidewall, which is composed of a plurality of juxtaposed segments in the shape of a hairpin inductor, each formed by two parallel tubular conductors, which are insulated from each other along their entire interface with the exception of a transverse section which electrically and hydraulically connects one end of one of the sections to the adjacent end of the other section.

Abstract: A device for taking samples of dust in a pipe or a chimney discharging gases, into the atmosphere.The device permits completely emptying the sampling tube of the dusts to be measured by means for rapidly and briefly closing the orifice of the sampling tube, which produces, once or several times during each sampling period, a pneumatic shock in the sampling tube which is subjected to pumping.Such a device permits effecting particularly precise measurements of the concentration of dust by weight. It also permits a continuous utilization of the device during very long periods of time without its clogging up.