Abstract: A heater has two, hollow, half-cylindrical heat guides fastened to each other at one side by an articulated connector and at the other side by a bolted joint. Internal surfaces of the heat guides represent the shape of the object being heated. On external surfaces of the heat guides, there are a series of, preferably flat splines. Lamellar heating elements are fastened to the splines. Mutual adherence surfaces of the heating elements and splines are shaped according to geometrical patterns, the appropriate selection of which changes the thermal characteristics of the heater over a wide range. The heater may be supplied from single- or three-phase mains. The heater is applicable especially for heating the cylinders, nozzles and tools of injection moulding and extrusion machines.

Abstract: Disclosed is a method of sealing salt mine headings. Salting out substances, adapted in quantity and quality for properties of effluent from the rift, are introduced into a rift in a rock mass, thus causing crystallization of salts identical or isostructural in relation to the salt forming the rock mass. The substances may be aqueous solutions of inorganic salts or they may be organic solvents. To avoid difficulty in mixing solutions, crevices are liquefied by introducing to their zone effluent and/or saline previously prepared and modified with salting out solutions. As inorganic salts, calcium chloride, magnesium chloride or mixtures thereof are used. As organic solvents, methanol or acetone is used.