GB922202A - Improvements in or relating to air blasting devices - Google Patents

Abstract

922,202. Blasting-cartridges. CHARBONNAGES DE FRANCE. Jan. 27, 1961 [Jan. 30, 1960], No. 3339/61. Class 9 (1). A blasting-cartridge utilizing compressed gas comprises a container 4, vents 8, a rupturable plate or piston 7 and a gas supply tube 5, the cartridge being attached to an inlet valve 2 and an oil reservoir 1. To reduce the possibility of explosion due to oil entrained with the gas and entering container 4 where the oil and gas mixture is subjected to a pressure and temperature increase, the tube 5 is provided with orifices 9. According to the invention, repeated tests have shown the following tube lengths and dispositions of orifices to be advantageous. A tube 5 which is at least twothirds the length of the container 4 and which has at least four orifices, the diameters of the orifices being at least one-third that of the internal diameter of the tube. The orifices may be positioned at equal intervals along the tube and their diameters may increase from a minimum at the inlet end to a maximum at the free end of the tube (see Fig. 3A). Alternatively, the orifices may be of equal diameter, the spacings between them decreasing from the inlet end to the free end of the tube. Also the orifices may be arranged helically along the tube. Again, according to the invention, it is advantageous to choose the positions and diameters of the orifices so that the mass of gas introduced per unit volume of the container is substantially constant at any given moment over the entire length of the container.