to wander and can make precise machining operations difficult in order to produce droplets in the 250 to 300 micron range the nozzle must have orifices in the range of 0 001 to 0 015 inch inside diameter preferably the orifices have an inside diameter or span of about 0 002 inch the use of grooved conical surfaces mated together allows for accurately formed orifices wile minimizing manufacturing costs the profile of the grooves is shown as basically semi circular however other two dimensional shapes such as rectangular or triangular slots also can be used fig1 and 2 show an embodiment where the conical surface of the plug is grooved to form orifices with a smoothly conical seat fig3 shows an alternative embodiment where the mating seat is grooved and the plug is smooth in order to form the orifices depending on the type of machining facilities available it may be easier to groove the outer surface of the plug than to groove the inner surface of the mating seat fig4 shows an alternative embodiment where both the conical surface of the plug and the mating seat both are grooved this doubles the number of orifices provided moreover the plug may be rotated with respect to the casing thereby altering the alignment of the grooves on the plug with respect to the grooves on the.