fig1 which illustrates a preferred embodiment of the present invention , shows an improved metering pin 10 having a head portion 20 , a first stage portion 30 and a second stage portion 40 . metering pin 10 is preferably formed from celcon m9004 material . head portion 20 includes a central recess 25 having end face 27 . recess 25 is preferably not formed to correspond exactly with the shape of the particular ball valve element employed by the nipple drinker into which metering pin 10 is inserted . instead , recess 25 preferably has a truncated conical shape which can receive a portion of the ball . the diameter of recess 25 is preferably wider than that portion of the ball contained within the recess when the ball contacts end face 27 . when used with a ziggity model 1025 drinker , end face 27 preferably has a diameter of approximately 0 . 085 ± 0 . 005 inch and the largest diameter of recess 25 is preferably approximately 0 . 194 ± 0 . 005 inch . such a configuration has been found to reduce adhesion between metering pin 10 and the ball so that the ball can rotate freely within the valve chamber of the drinker . first stage portion 30 includes a conical taper 35 opposite head portion 20 . in preferred embodiments first stage portion 30 and second stage portion 40 are both substantially cylindrical , although of different dimensions . between first stage portion 30 and second stage portion 40 is disposed an inclined transition surface 37 . the diameter of first stage portion 30 is preferably larger than the diameter second stage portion 40 , and the length of first stage portion 30 is preferably less than the length of second stage portion 40 . when employed in a ziggity model 1025 drinker first stage portion 30 is preferably dimensioned to have approximately 0 . 004 inch total gap with respect to the gap opening , the interior diameter of the cap opening being 0 . 004 inch ( approximately ) larger than the exterior diameter of portion 30 . at the same time , second stage portion 40 would have approximately 0 . 008 inch total gap with respect to the cap opening , the internal diameter of the cap opening being approximately 0 . 008 inch larger than the exterior diameter of portion 40 . in this preferred arrangement the respective component dimensions would be , for example : the precise dimensions of these portion 30 and 40 relative to the cap opening will determine the exact rate of water flow available into the drinker at a given water pressure since the outlet opening from the drinker will preferably be relatively enlarged so as not to restrict the flow once the valve is opened . manufacturing tolerances are determined by the degree of precision desired in watering rates , although the tolerances noted above have been found advantageous and obtainable in practice with the preferred material . it should also be noted that other relative dimensions of components are of some significance . when metering pin 10 is used with the ziggity model 1025 drinker it is also preferable to modify the drinker cap as shown in fig4 and 5 . revised cap 50 includes a lower portion 60 for insertion into the standard base of the ziggity model 1025 drinker housing to form the upper section of the valve chamber . revised cap 50 further includes upper portion 70 which forms an exterior portion of the drinker housing and is receivable within a standard saddle for the ziggity model 1025 drinker . lower portion 60 includes a chamber 62 for receiving a standard ball valve element . multiple guiding projections 64 are located on interior surface 66 of chamber 62 to facilitate ball movement during valve operation . where lower portion 60 joins upper portion 70 there are inclined surfaces 68 in chamber 62 which serve as upper stops to motion of the ball valve element . slots 72 are provided in surfaces 68 to permit fluid flow into chamber 62 even when the ball valve element is held in its uppermost position . slots 72 extend into upper portion 70 until reaching surface 74 which serves as the upper stop to motion of head portion 20 of metering pin 10 . cap opening 76 extends from surface 74 to the top surface 78 of upper portion 70 and is preferably a cylindrical opening of constant diameter . top surface 78 includes a recess 80 for receiving a standard sealing o - ring . during assembly , metering pin 10 is preferably inserted into chamber 62 with taper 35 penetrating cap opening 76 . head portion 20 is pushed into chamber 62 until it abuts surface 74 . cap 50 is then inserted within the standard base portion . the distance between surfaces 68 and 74 and the thickness of head portion 20 relative to the size of the ball valve element are preferably dimensioned such that head portion 20 is movable along longitudinal axis 90 , even when the ball valve element abuts surface 68 , to such an extent that it does not restrict flow of water into the drinker . similarly , the exterior diameter of head portion 20 is preferably sufficiently smaller than the diameter of surface 74 so as not to restrict the flow of water . thus , the closest dimensions ( and resultant flow restriction ) preferably occurs within cap opening 76 . in the preferred embodiment described above the length of cap opening is less than the length of first stage portion 30 . preferably the relative positions and lengths of metering pin 10 , portions 30 and 40 and cap opening 76 are such that portion 30 is within cap opening 76 when the drinker is triggered by side to side actuating force and that only portion 40 is within cap opening 76 when the drinker is triggered by vertical actuating force . for example , respectively component dimensions could be : distance of surface 74 from junction of lower portion 60 and upper portion 70 = 0 . 132 ± 0 . 005 inch thus , in preferred embodiments the flow rate through the drinker during side to side triggering is determined by the relative dimensions of portion 30 and cap opening 76 while during vertical triggering the flow rate through the drinker is determined by the relative dimensions of portion 40 and cap opening 76 . it will now be evident that cylindrical configurations are not the only permissible designs for metering pin 10 . while cylindrical formations of portions 30 and 40 are often commercially practical , other configurations will offer similar advantages . one such embodiment is shown , for example , in the generic drinker of fig6 . a common requirement is , however , that greater fluid flow be permitted through cap opening 76 when the drinker is triggered vertically than when the drinker is triggered side - to - side . typically , this can be accomplished by increasing the gap between portion 40 and cap opening 76 as compared with the gap between portion 30 and cap opening 76 . in fig6 for example , metering pin 110 is provided with circumferential slots 140 between cylindrical portion 130 and head portion 120 . metering pin 110 is disposed in valve chamber 162 between cap 150 and standard base 200 along with standard actuating pin 210 and standard ball valve element 220 . when actuating pin 210 lifts ball valve element 220 upward along axis 230 in response to side - to - side force fs , metering pin 110 also moves upward along axis 230 , but slots 140 do not extend above cap opening 176 . however , when actuating pin 210 lifts ball valve element 220 in response to vertical force fv , metering pin 110 is normally moved higher along axis 230 such that slots 140 do not extend above cap opening 176 and a greater rate of water flow is permitted . in contrast with metering pin 10 , metering pin 110 has been formed with polyethylene material and with a hollow core to improve dimensional consistency . for most applications noted by the applicant thus far metering pin 10 is , however , preferred over metering 110 . thus , by permitting two different flow rates the total volume of water available during actuating is no longer merely proportional to the water pressure . since these two flow rates typically occur during different stages of poultry growth , water availability can be optimized according to poultry needs while maintaining minimal , if any , leakage . it has been found in some instances with the present invention that adequate water is available to day - old chicks with only 3 inches of water pressure and adequate water if available to poultry in the last 10 days of growth with only 8 inches of water . with such low water pressures good actuation sensitivity is also maintained and leakage is minimized . also , the preferred embodiments have been described above primarily with respect to the ziggity model 1025 drinker because that drinker has achieved widespread application . the present invention can , however , be readily applied to many other nipple drinker styles with minimal effort . although the present invention has been described above in detail , the same is by way of illustration and example only , and not to be taken as a limitation of invention . the spirit and scope of this invention are instead limited only by the scope and content of the following claims .
a metering pin is provided having two portions of different external configuration , each of which portions are insertable into the fluid flow path for restricting fluid flow under different actuating conditions . these two portions can be dimensioned to be readily retrofit into various existing nipple drinkers according to the configuration of the drinker inlet . the specific dimensions of each portion relative to the drinker inlet can be selected according to desired flow rates at different levels of poultry growth .