an aerosol - type dispenser system 1 including a first exemplary embodiment of an aerosol tip mechanism 2 according to the present invention is shown in fig1 . as shown in fig1 a first exemplary embodiment of the aerosol tip 2 according to the present invention is coupled to a body portion 103 which has a substantially tubular shape and to a piston 110 having a substantially tubular portion 112 extending inside and along the body portion 103 . the body portion 103 includes a lower base portion 1031 that extends radially beyond a lower end of the body portion 103 in a flange - like structure which is against the piston shoulder 1101 when the pump is in its resting position . a flexible outer shell 40 covers both the aerosol tip mechanism 2 and the body portion 103 . the tubular portion of the piston contains a hollow axial inner channel 1041 which communicates fluid toward the body portion 103 via a radial channel 114 on each side of the inner channel 1041 when the pump is in a loaded or “ cocked ” position . as shown in fig1 the inner channel of the piston 1041 is in fluid communication with a liquid reservoir 115 . the overall pump mechanism 120 , which includes the piston 110 , the body portion 103 , and the flexible outer shell 40 , channels the liquid from the liquid reservoir 115 along a fluid communication path encompassing the radial opening 114 in the piston 110 and a compression chamber 125 . in this regard , it should be noted that the aerosol tip according to the present invention is intended to be used in conjunction with a wide variety of liquid dispensing systems , one example of which ( shown in fig1 ) combines a spring mechanism ( defined by portion 40 a of the flexible outer shell 40 ) and a collapsible bladder 124 . the collapsible bladder is surrounded by a rigid spray container 1102 . it should be understood that the pump mechanism 120 is merely an exemplary representation of a wide variety of dispensing systems . in the configuration shown , the piston 110 and the rigid spray container 1102 comprise one piece . when the piston 110 is slid downward relative to the body portion 103 , liquid from the liquid reservoir 115 is initially channeled through the radial opening 114 in the piston 110 and subsequently channeled into the compression chamber 125 when the pump is cocked . when the piston 110 is released , the spring mechanism forces the piston 110 upward , in turn forcing the trapped liquid through outflow channel holes 208 a , 208 b , 208 c of the nozzle and upward to the aerosol tip 2 of the dispenser system . fig2 is a cross - sectional view showing one of the channel holes , hole 208 a . [ 0028 ] fig7 shows a first exemplary embodiment of the aerosol tip mechanism 2 according to the present invention . the tip mechanism 2 includes a rigid annular cap portion 20 , which has an inner cap portion 21 situated beneath a cap flange 22 , and a rigid nozzle portion 24 having a shaft 28 received within the center of the inner portion 21 of the annular cap 20 . a swirling chamber 32 lies in the space defined by the inner portion 21 of the cap 20 and the rigid center shaft 28 . a flexible outer shell 40 , which surrounds and substantially constrains the nozzle portion 24 and the cap flange 22 , interfaces with the inner cap portion 21 and the center shaft 28 to form a normally - closed one - way outlet valve 35 which encloses the swirling chamber 32 . when the pressure in the swirling chamber 32 is high enough to expand the thick base 35 a of the one - way outlet valve 35 , the thin and distal portion 35 b of the valve subsequently opens ( at which time the thick base 35 a has already collapsed back to its normally - closed position ), thereby providing for one - way discharge of fluid from the outlet valve . [ 0029 ] fig3 shows an enlarged view of an embodiment of the rigid nozzle portion 24 of the aerosol tip 2 according to the present invention . the nozzle 24 includes a circular base section 201 widening in a radial direction along the elongated axis of the dispenser system , and the base section 201 is connected to a circular rim 203 . on top of the circular rim 203 , the nozzle 24 narrows along the elongated axis in a conic section 205 . vertical outflow channel holes , such as 208 a which extends through the rim 203 and the conic section 205 , provide fluid communication channels for liquid entering the swirling chamber , as shown in fig2 . the conic section 205 narrows into a cylindrical section 241 which , in between each of the outflow paths of the outflow channel holes , presents an undercut or depression 211 designed to accept and fasten corresponding cap latches 255 of the cap 20 , which is shown in fig4 to form a tight seal between the cap 20 and the nozzle 24 of the aerosol tip 2 . a valve section 207 is formed between the flexible shell 40 and the cylindrical portion 241 . referring back to fig2 and 5 , liquid forced upward through the channel holes 208 a , 208 b , 208 c in the nozzle 24 are channeled along the vertical section 207 to a nozzle spiral feed channel section 210 . it is noted that although there are three channel holes in the figures , this number is merely - exemplary . referring to fig5 which shows a top plan view of the nozzle 24 , the channel holes 208 a , 208 b , 208 c feed liquid via valve section 207 to the bottom of corresponding spiral feed channels 218 a , 218 b , and 218 c , and it should be apparent that the interface between the nozzle 24 and the cap 20 define the spiral feed channels and the connection section between the channel holes and the feed channels . a brief description of the fluid mechanics involved in the spiral feed channels 218 a , b , c and the swirling chamber 32 is helpful here . the swirling chamber 32 is used to create a spray pattern for the discharged aerosol , and several factors affect the physical characteristics of discharged spray pattern . first , the length of the interface defining the outlet valve 35 is the main parameter controlling the cone angle of the spray pattern , i . e ., the shorter the length of the interface at the outlet valve 35 , the wider the spray pattern . second , the greater the pressure differential between the outside and the inside of the outlet valve 35 , the greater the homogeneity of the particles and the smaller the particle size . third , the smaller the diameter of the opening defined by the separated outlet valve 35 , the smaller the particle size in the spray . additionally , the symmetry and tightness of the outlet valve 35 impacts the size of the aerosol droplets because of asymmetries in the interface , e . g ., if the portion of the flexible outer shell comprising part of the outlet valve 35 is not centered on the center shaft 28 , then the tightness of the valve will not be uniform and the valve 35 will not be able to achieve the desired aerosol spray . in order to increase the homogeneity of the spray - particle size and generally reduce the particle size , the dispensing system according to the present invention maximizes the relative pressure differential between the outside and the inside of the outlet valve 35 by means of minimizing the resistance sources in the fluid path , also referred to as “ head loss ” in fluid mechanics . in this regard , the following parameters are minimized : the length of the fluid channels incorporated in the present invention ; the rate of reduction of the fluid - channel width as the fluid channel approaches the swirling chamber 32 ; and the rate of change of the fluid - channel angle relative to the swirling chamber , i . e ., the transition angle between the channel holes 208 a , 208 b , 208 c and the corresponding spiral feed channels 218 a , 218 b , and 218 c are inclined as gradually as possible without unduly extending their overall length in order to reduce the k factor of the minor loss equation ( 3 ). as can be seen from fig5 and 6 , each spiral feed channel 218 a , 218 b and 218 c is widest at its respective bottom portion and becomes narrower as it gradually curves upward in a clockwise direction around the center shaft 28 so that the head loss is reduced due to two effects : a ) because of the shorter length of the narrow end of the feed channels , and b ) the smoother curve between the vertical portion of the shaft 28 and the horizontal end of the feed channels . liquid that is channeled upwards along the spiral channels 218 a , 218 b , 218 c travels along a gradual , clockwise - curving path ( such as path 240 shown in fig6 ) and suffers only relatively minor head losses because of the absence of sharp edges or turns along the path which contribute to head losses . each spiral feed channel 218 a , b , c narrows into a ledge surrounding the center shaft 28 , each of which feed channel ends with an upwardly sloping and curving ramp 220 a , 220 b , 220 c . liquid streams travel along the ramps 220 a , b , c , and spiral upwards around the center shaft 28 in an annular swirling chamber 32 situated between the shaft and the cap portion 20 which has an internal profile complementary to the ramp of the nozzle . because the ramps 220 a , b and c are angled 120 degrees apart from one another , the spiral trajectories of the liquid channeled from each ramp into the swirling chamber 32 are spaced apart from one another such that the liquid expelled in trajectory 230 a from the ramp 220 a to the chamber 32 reaches halfway to the top of the swirling chamber before this liquid merges with the liquid 230 b entering the swirling chamber 32 from an adjacent spiral feed channel 218 b . the mutual non - interference of liquid flowing in the separate trajectories 230 a , 230 b , 230 c ( not shown ) from the corresponding spiral feed channels 218 a , 218 b , 218 c also assists in minimizing head losses , as interference between the liquid streams can also cause head losses and / or turbulence . using the embodiment of the aerosol tip incorporating the spiral feed channels 218 a , 218 b , and 218 c and the swirling chamber shown in fig6 the average particle size of the discharged spray pattern is below 40 μm , and is sprayed in a more homogeneous pattern as judged by the narrow deviation of particle sizes according to the melverne test . returning to fig7 the mechanism for ensuring the centering of the flexible outer shell 40 over the center shaft 28 , thereby ensuring a symmetrical and tight outlet valve interface 35 between the flexible outer shell 40 and the center shaft 28 , is illustrated . the outlet portion of the outer shell 40 rests between the upper , or the flange , portion 22 and the lower portion 21 of the cap 20 in the shape of a foot , with the heel 401 and the “ toes ” 402 of the outlet portion of the shell 40 forming the outlet valve 35 in conjunction with the rigid shaft , and the “ heel ” of the outlet portion immovably fixed in the boots 303 where the flange 22 connects to the lower portion 21 of the rigid cap 20 . the rigid cap 20 is also immovably fixed in relation to the center shaft 28 , such that there is an annular clearance and constant distance 310 between the lower portion of the cap 21 and the shaft 28 , which clearance 310 provides space for the swirling chamber 32 , and also fixes the distance between the boots 303 and the outlet valve 35 , providing for exact concentricity between the components during assembly . for the purpose of providing a firm guide for centering the cap 21 onto the shaft 28 , both components are made from rigid materials such as poly acetal , polycarbonate or polypropylene , while the elastic outlet valve portion 35 , made from kraton ™, polyethylene , polyurethane or other plastic materials , thermoplastic elastomers or other elastic materials , is free to adjust and fit concentrically within the rigid boots 303 . by constraining the lateral movement of the outer shell 40 , the length of the outlet valve 35 can be precisely dimensioned to tightly enclose the swirling chamber 32 without having to add additional constraints to account for improper alignment during assembly . the one - way valve described herein prevents external contaminants from contacting the fluid within the spray container , and allows the fluid to remain sterile indefinitely . an advantage of the aerosol tip according to the present invention is that the number of parts which constitute the aerosol tip mechanism is reduced in comparison to conventional aerosol - tip and nozzle mechanisms , i . e ., these conventional mechanisms typically include gaskets and dead volumes , as well as allowing direct communication between the pump and the external air , making a one - way valve of the type described herein impracticable . as can be seen from fig7 the aerosol tip according to the present invention can be made from three discrete parts : a flexible outer shell 40 , a rigid cap portion 20 and a rigid nozzle portion 24 including a rigid shaft portion . because only three discrete parts are required , the cost and complexity of manufacturing are reduced . yet another advantage of the aerosol tip according to the present invention is that the configuration of the outlet valve portion 35 of the aerosol tip is preserved and prevented from either over and under - extending laterally with respect to the shaft of the nozzle portion in response to the forces applied by the pressurized fluid in the fluid channel . still another advantage of the aerosol tip according to the present invention is that the average fluid - particle size in the dispensed aerosol spray is optimally controlled and generally reduced owing to the configuration of the fluid channels which are designed specifically to limit head losses . average fluid - particle size is also optimally controlled by maintaining exact concentricity of the components of the symmetrical outlet valve , which greatly reduces the risk of undesirable discharge - particle characteristics and assures - better reproducibility of desired discharge - particle characteristics from pump to pump . while specific embodiments have been described above , it should be readily apparent to those of ordinary skill in the art that the above - described embodiments are exemplary in nature since certain modifications may be made thereto without departing from the teachings of the invention , and the exemplary embodiments should not be construed as limiting the scope of protection for the invention as set forth in the appended claims .