nozzle assembly 38 includes an internally threaded support flange 40 secured to mounting flange 34 by a set of bolt and nut fasteners an externally threaded nozzle tube 42 threaded into the support flange and extending into pipe section 28 to a point below the funnel section of unit 22 and a locking ring 44 threaded onto nozzle tube 42 and adapted to bear against support flange 40 for locking the nozzle tube in a desired position as best illustrated in fig3 a nozzle 46 is threaded into a leading internally threaded end of the nozzle tube to provide an orifice 48 the trailing end of the nozzle tube is adapted to be connected to the gas supply system 16 through an adapter 50 it will be appreciated that by backing off the locking ring and rotating the nozzle tube the position of the nozzle may be adjusted relative to the funnel section to alter the flow characteristics of the material being fed from the pressure vessel into the pneumatic conveying line once the positioning of the nozzle has been set it may be fixed in place by running the locking nut up into engagement with the support flange the flow characteristics of the unit further may be altered by the use of nozzles with orifices of different sizes gas supply system 16 includes a main supply line 52 connected to a source of gas under pressure a first branch line 54 and a second branch line 56 the main supply line includes a shut off valve 58 branch line 54 interconnects the main supply line.