Abstract

An airgun impulsive energy source has an elongated shaft bearing surrounding the shaft of the reciprocatable shuttle for guiding the shuttle and preventing its operating or firing pistons from contacting their respective cylinder walls. The illustrative embodiment of this airgun is proportioned to be self-firing with a fast repitition rate. This airgun has an elongated cylindrical housing with discharge ports in a cylindrical wall positioned between the operating and firing chambers. The shuttle-guiding shaft bearing is positioned in the cylindrical housing between the ports and an operating chamber. This shaft-guiding bearing has a length which is more than 1.7 times the diameter of the shuttle shaft, while the operating and firing pistons have diameters which are slightly less than the diameter of their respective cylinder walls for eliminating contact of these pistons with their cylinder walls, thereby advantageously dramatically increasing the firing cycles which can occur before the need for replacing any worn parts. Moreover, only the shuttle shaft guiding bearing is replaced, instead of the cylinder walls. The housing includes internal through passages which convey high pressure gas longitudinally through the airgun so that it can be coupled to subsequent airguns connected in series with the first one. Thus, a single source of high pressure gas may be utilized and fed in series through a sequence of airguns forming a flexible "string" of airguns capable of being inserted into and used for cleaning pipes of heat exchangers, boilers, water heaters and other internal regions of closed vessels, which are normally very difficult or impossible to reach into for cleaning. The discharges of pressurized gas by the string of airguns in liquid, usually water, in such equipment is used to dislodge sediment and deposits from the internal surfaces of such confined regions so that the loosened foreign materials can then be flushed out by the flowing liquid.