nozzle 44 has a tubular body 73 with threads 74 the threads screw into the threaded box end 66 of an eduction pipe section 28 to seal off the end of the outer conduit 42 the threads 74 duplicate the threads on the pin end of an eduction pipe section 28 the nozzle 44 extends from the threads 74 upwards through the box end of the eduction pipe 28 into the inner conduit 38 of the pipe section 28 above those external threads is a barrel 77 which extends through the box end fitting or the pipe sections o ring seals cooperate between the barrel 77 and the box end fitting to seal the connection of the nozzle 44 to the eduction pipe section 28 when the nozzle 44 is in place in the lower end of the eduction pipe the upper end of the barrel 77 lies below the lower end of the inner conduit in the eduction pipe a tubular nipple 79 is carried concentric to the axial bore of the nozzle body 73 extending the body bore into the inner conduit 38 of the eduction pipe 28 the outer diameter of the nipple is a selected amount less than the inner diameter of inner conduit 38 so that an annulus is formed between the nozzle and the inner conduit and that annulus is in fluid flow communication with the annulus passage formed in the eduction pipe between its inner and outer conduits as a result pressurized air which is being forced down through the outer conduit 42 as shown by arrows 76 is reversed as shown by arrows 78 and forced to flow up through the inner conduit 38 as shown by arrows.