Improvements in or relating to equipment for bore-holes for short-firing and other purposes

922,418. Fluid-pressure blasting devices. HAYDEN-NILOS Ltd. Dec. 29, 1960 [Dec. 31, 1959], No. 44353/59. Class 9 (1). An infusion equipment tube 1 is surrounded by a resilient tubular seal 2 constrained at its ends to the tube by shrouds 3 and 4, such that the full pressure of water supplied to the bore 8 is received by the seal through the transverse ports 7, while the outlet end of the bore 8 is closed by a spring-loaded reducing valve. The shrouds are formed integrally with inlet and outlet caps 5 and 6 respectively, which are counter-bored and tapped to screw on to threaded ends of the tube 1, while the main tube 9 is screwed on to inlet cap 5. The untapped portion of the outlet counter-bore 10 carries the headed stem of the valve seating member 14 whose compression spring 13 resides in the narrower counter-bore 12. The seating pad 15 of the valve member 14 beds on an annular seat 16 at the entrance to the bore 8. When the seal 2 is inflated by the water from tube 9 the increasing pressure opens the valve so that water may enter the counterbore 10 and pass into the shot hole through holes 17 until the pressure drop across the valve reaches the value at which it closes, said valve being determined by the stiffness of the spring 13. An alternative form of the invention has an outlet end cap counter-bored from its outer end leading inward to a narrower bore providing a seating for a ball valve which is held in position by a compressed spring retained by a union at the outer end of the counter-bore. The spring may be replaced or its loading altered by removing or adjusting the union, as the case may be; the water flow when the valve operates is here entirely through the counter-bore and union. Specification 853,272 is referred to.