adjust the position of the gas tubes 230 rather that position is pre established and maintained by the position of the jet positioning apertures 143 the position of the impingement stream directional passage 211 will have a central axis that intersects a central axis of the corresponding liquid channel 112 below the liquid discharge end 116 of that liquid channel 112 and preferably in a perpendicular relationship according to the potentially preferred practice the gas directional passages 211 in the impingement jet system 200 have a diameter which is greater than the width dimension of the corresponding liquid channel 112 in the liquid jet module 100 and resultant liquid streams 11 most preferably the cross sectional diameter of the gas directional passages 211 will be as large a possible while maintaining the substantially centered relation relative to the corresponding liquid streams 11 and not allowing the impingement stream 19 therefrom to interfere with the adjacent liquid streams 11 or the adjacent impingement streams 19 in this regard it is desirable that the diameter of the gas directional passages 211 are at least as large as the diameter of the lines feeding into the gas tubes 230 such that the gas directional passages 211 do not create a flow restriction in the system by way of example only a diameter of about 43 mils for the gas directional passages 211 has been found to provide good performance when used with liquid channels 112 having a cross section of about 14 mils although larger or smaller diameters may be used if desired the impingement jet system 200 may be installed into and removed from the liquid jet module 100 as a single module of course in actual practice the impingement jet module 100 may.