referring to the drawings , and to fig1 in particular , a pin jet nozzle 10 in accordance with the present invention is illustrated . the pin jet nozzle 10 includes a body member 12 , an orifice member 14 fixedly mounted in the body member 12 , and a pin member 16 mounted to the body member . with additional reference to fig2 the body member 12 is preferably constructed of nickel , silver , or stainless steel , but may be constructed of other suitable material or combination of materials . the body member 12 has a lower portion 20 with an external helical thread 22 and an upper portion 24 with flat faces 26 that can be engaged with a wrench or the like in a well - known manner for securing the pin jet nozzle 10 to a threaded opening of a pressurized hydraulic system ( not shown ). it will be understood that the pin jet nozzle 10 can be secured to the pressurized hydraulic system through other well - known securing means , such as welding , press - fitting , mutually engaging structure , and so on . as shown in fig3 an internal chamber or bore 30 is formed in the body member 12 and is preferably concentric with a central axis 32 of the body member . the bore 30 preferably has lower , intermediate and upper bore portions 33 , 35 and 37 , respectively , that decrease in diameter in a step - wise fashion from the bottom surface 34 to the top surface 36 of the body member 12 . the bore 30 is arranged for receiving fluid from the pressurized hydraulic system and preferably includes a first inner transitional frustro - conical surface 38 that extends generally upwardly and inwardly from the bottom surface 34 to the lower bore portion 33 , a first inner circumferential surface 40 that defines the lower bore portion 33 and extends generally upwardly from the first transitional surface 38 , a second inner transitional frustro - conical surface 42 that extends generally upwardly and inwardly from the first circumferential surface 40 to the intermediate bore portion 35 , a second inner circumferential surface 44 that defines the intermediate bore portion 35 and extends generally upwardly from the second transitional surface 42 , a third inner transitional frustro - conical surface 46 that extends generally upwardly and inwardly from the second circumferential surface 44 to the upper bore portion 37 , and a third inner circumferential surface 48 that defines the upper bore portion 37 and extends upwardly to an orifice receiving chamber 50 from the third transitional surface 46 . although a particular configuration of the internal bore 30 has been shown and described , it will be understood that other bore configurations with more or less bore portions of different diameters , cross - dimensions , and / or cross sectional shapes can be provided . with particular reference to fig4 and 5 , an annular wall 52 extends upwardly from the upper surface 36 to define the orifice receiving chamber 50 . the annular wall 52 includes a lower wall portion 54 that extends upwardly from the upper surface 36 and an upper wall portion 56 that initially extends upwardly from the lower wall portion 54 , as shown in fig4 . preferably , the upper wall portion is thinner than the lower wall portion so that it can be bent or otherwise deformed to extend inwardly toward the central axis 32 of the of the body member 12 and generally perpendicular to the lower wall portion 54 , as best shown in fig5 . prior to deformation of the upper wall portion 56 , the orifice member 14 is inserted into the orifice receiving chamber 50 . once the upper wall portion 56 is deformed , the orifice member 54 is securely held within the orifice receiving chamber 50 and sandwiched between the upper wall portion 56 and the upper surface 36 . standard metalworking techniques can be used to deform the upper wall portion over the surface of the orifice member 14 . the orifice member 14 should be held in a flat position , generally perpendicular to the central axis 32 of the body member 12 . other techniques for firmly securing or holding the orifice member 14 on or in the body member 12 can be employed . the orifice member 14 is preferably constructed of wear - resistant material that can be formed to precise tolerances , such as artificial jewel material , including ruby and / or sapphire , or other suitable material . the outer shape of the orifice member 14 is not critical , but the flat disk illustrated is preferred for ease in locating the orifice member 14 in the orifice receiving chamber 50 . an orifice 60 is formed in the orifice member 14 , preferably at a center of the disk and extends from a lower surface 62 to an upper surface 64 thereof . when the orifice member 14 is installed in the body member 12 , the orifice 60 is preferably in axial alignment with the central axis 32 and the upper bore portion 37 of the body member 12 . the orifice member is constructed of the wear - resistant material to precise tolerances , including at least one surface which is smooth and polished with no surface pocketing , scarring , voids , or imperfections . the orifice 60 is precision - cut with a laser and then polished by wire polishing to a tolerance which is not possible with machining or extrusion technologies . with reference to fig3 and 5 , the pin member 16 of the nozzle 10 has a support post 70 and an impingement pin 72 connected at a terminal end 74 of the support post , as in the prior art . the support post is generally inverted j - shaped and has a mounting end 76 that is securely affixed onto or into the body member 12 . the terminal end 74 of the support post is preferably aligned with the central axis 32 of the body member 12 , with an impingement face 74 73 of the impingement pin 72 centered over the orifice 60 . by virtue of the orifice size and tolerance , which define an exact output for each nozzle , the impingement pin 72 and the diameter of the impingement face 73 may be smaller in diameter than a comparable impingement pin of prior art pin jet nozzles . it has been common in the prior art to provide an impingement pin larger in diameter than the outlet orifice . as in the prior art , the impingement pin 73 is preferably axially positioned from the orifice 60 at a fixed distance . the exact dimension of the pin , its position and the geometry of its taper are believed to be within the knowledge of one skilled in the art . the above - described arrangement of the present invention is capable of generating an evaporative fog with fluid particles that have a diameter of less than fifty micrometers . further fluid input and output characteristics of the pin jet nozzle , as well as its use , are more fully disclosed in u . s . pat . no . 5 , 620 , 142 to elkas , the disclosure of which is hereby incorporated by reference in its entirety . accordingly , the characteristics and use of the pin jet nozzle will not be further described . by eliminating the prior art insert and mounting the orifice member 14 directly to the body member 12 in accordance with the present invention , deterioration of the insert under acid cleaning , as well as leakage between the insert and nozzle body are eliminated . it will be understood that terms of orientation and / or position as used throughout the specification , such as top , bottom , upwardly , downwardly , inwardly , lower , intermediate , and upper , as well as their respective derivatives and equivalent terms , refer to relative rather than absolute orientations and / or positions . it will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof . it is understood , therefore , that this invention is not limited to the particular embodiments disclosed , but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims .