Abstract: The annular air-hammer apparatus for drilling holes comprises a shell hav fitted co-axially therein a chips-receiving sleeve, a hollow cylindrical case, and a ring-shaped hammer capable of reciprocating back and forth. The lower part of the shell accommodates a rock-cutting tool capable of moving axially with at least one blow-off passage formed by at least a single longitudinal groove made on the outer cylindrical surface of the rock-cutting tool. With the rock-cutting tool in its uppermost position, the blow-off passage communicates with an outlet space provided between the shell and the case.

Abstract: An annular air-hammer apparatus for drilling holes incorporates a hollow cylindrical case with a stepped bore which has inlet and outlet ports. A rock-cutting tool with an axial opening is fitted to the case at the forward end thereof. A chips-receiving sleeve and a stepped ring-shaped hammer are located inside the case, whereby the hammer forms a working-stroke chamber with the case and an idle-stroke chamber with the case, the rock-cutting tool and the chips-receiving sleeve. The chips-receiving sleeve has a cylindrical protuberance at its upper end which interacts with the hammer when this is in its topmost position. A channel is provided in the idle-stroke chamber at that side thereof which faces the upper end face of the hammer.

Abstract: A method for the electric purification and decontamination of liquids containing suspended and dissolved matter, such as mineral, organic and biological substances, comprises passing a pulsating electric current through a starting liquid, the current having sufficient pulse duration and voltage to cause electric discharge between the electrodes. An apparatus for realizing the method of electric purification and decontamination of liquids comprising a coagulation chamber with at least two rod-type electrodes electrically insulated by means of individual insulators from the housing of the coagulation chamber and mounted together with their insulators to execute reciprocal motion along their longitudinal axes.