fig1 illustrates schematically a dental handpiece system 10 according to the present invention . according to one aspect of the present invention , system 10 employs multiple dental handpieces . in the present illustration , four such handpieces will be shown , however , it will be understood that any selected number of handpieces may be utilized under the present invention . in fig1 system 10 includes a set of handpieces 12 , individually handpiece 12 a - 12 d . each handpiece 12 carries a tool 14 , individually tools 14 a - 14 d . in this particular illustration , each handpiece 12 is a high - speed turbine drill rotating the corresponding tool 14 at high speeds , e . g ., 350 , 000 rpm , for purposes of executing dental procedures . dental handpiece systems include other , i . e ., low speed or ultra sonic , handpieces which do not necessarily undesirably collect bio - contaminants during use . however , such other handpieces typically also operate in the fashion illustrated relative to handpieces 12 , i . e ., receive a flow of supply air and return the supply air through an exhaust system . the present invention is well suited for operation in conjunction with such other handpieces and is especially useful for filtering oil from the return air relative to surrounding ambient air . the present disclosure focuses , however , on the undesirable collection of bio - contaminants by high - speed handpieces such as handpieces 12 illustrated in fig1 . each handpiece 12 couples to the remainder of system 10 by means of a tubing set 16 , individually tubing sets 16 a - 16 d . each tubing set 16 includes a plurality of conduits . in addition to those illustrated herein , tubing sets 16 include cooling fluid , e . g ., cooling air or water , supply and return conduits and the like ( not shown herein ). as relevant to the present invention , each tubing set 16 includes an air supply conduit 18 and an air return conduit 20 , individually air supply conduits 18 a - 18 d and air exhaust conduits 20 a - 20 d . air forced down a given supply conduit 18 strikes a turbine ( not shown ) within the corresponding handpiece 12 causing the corresponding tool 14 to rotate at high speed . after striking the turbine , the air travels back to the dental unit ( not shown in fig1 ) along the corresponding return conduit 20 . a compressed air supply 30 couples to each of the air supply conduits 18 by way of an operator foot control 32 , e . g ., foot operated control . in this manner , an operator selectively introduces air from supply 30 into a selected one of air supply conduits 18 and thereby selectively operates one of handpieces 12 . each return conduit 20 terminates at a unidirectional valve 40 , individually valves 40 a - 40 d . each valve allows a one - way flow of return air out of the corresponding return conduit 20 and into a common manifold 42 . as may be appreciated , air exiting a given return conduit 20 and passing through the corresponding valve 40 into common manifold 42 cannot thereafter reenter any one of return conduits 20 by virtue of the valves 40 . in other words , once air enters common manifold 42 it cannot thereafter reenter any conduit 20 . common manifold 42 couples to ambient air space 44 by way of a removable filter unit 46 . filter unit 46 includes a hepa filter element 46 a mounted therein . it is suggested , however , that hepa - filter element 46 a be permanently mounted within unit 46 and that unit 46 be removably mounted . as will be appreciated , back - pressure created within common manifold 42 by virtue of filter unit 46 cannot cause air flow back into return conduits 20 by virtue of unidirectional valves 40 . accordingly , once air reaches common manifold 42 it is destined to exit system 10 only by way of filter unit 46 . debris accumulates at filter element 46 a and eventually reaches a given magnitude , filter unit 46 may be replaced , e . g . once - a - week . system 10 thereby protects ambient air space 44 against contamination from oil as originating at compressed air supply 30 or , more importantly , bio - contaminants as carried from the patient by handpieces 12 . filter element 46 a provided as a hepa - filter at a 0 . 1 micron filtration rating eliminates most contaminants , i . e ., blood , saliva , bacteria , fungus , pulled into the handpiece by vacuum effect during use thereof or other contaminants passing through the handpiece , e . g . oil from the compressed air supply 30 . filter unit 46 may be disposed of with other bio - hazardous materials from the dental office . thus , system 10 addresses contamination control issues in dental operations . by virtue of valves 40 , return air cannot pass from one handpiece back into another handpiece . furthermore , return air must pass through filter element 46 a before it enters ambient air space 44 . because filter unit 46 is replaceable , accumulated microorganisms , fungus or mold growing at filter unit 46 need not accumulate at all or beyond undesirable magnitude . system 10 thereby protects doctors , patients and staff against exposure to undesirable bio - contaminants , microorganisms , fungus , and mold in the operating area . in this aspect , system 10 eliminates a source of contamination and health risk for patients , doctors , and staff . while illustrated in fig1 as an integral part of a dental handpiece system , the present invention may be applied to an existing dental handpiece system by adding a multiport antibackflow manifold 100 as illustrated in fig2 . in fig2 the manifold 100 is illustrated in partial sectioned view . manifold 100 includes a plurality of inlets 138 each communicating with a corresponding ball - type check valve 140 . at the downstream side of each valve 140 is the common manifold space 142 . at the upstream side is the corresponding inlet 138 . fig2 illustrates manifold 100 as mounted to a dental delivery unit 200 . the dental delivery unit 200 is an enclosure structure in which the terminal ends of air return conduits 120 may be found . as illustrated in partially broken away view in fig2 unit 200 includes a floor 202 and surrounding wall structures 204 . manifold 100 mounts on the upward facing surface of floor 202 in the vicinity of an opening 206 thereof . the upper portion 100 a of manifold 100 includes an opening 208 therethrough . a mounting bolt 210 passes through aperture 208 and a second smaller opening 212 of floor 202 to engage a nut 214 therebelow . a foot 216 extending downward from upper portion 100 a also engages in abutment the upward facing surface of floor 202 . in this manner , upper portion 100 a of manifold 100 finds secure and stable attachment within unit 200 upon floor 202 and in the vicinity of opening 206 . as illustrated in fig2 a filter unit 146 includes a stem portion 146 b and a flange portion 146 c . a filter element 146 a rests within the flange portion 146 c of each filter unit 146 . stem 146 b includes a central conduit 146 d through which air passes and reaches filter element 146 a for elimination into the ambient air space 144 . stem portion 146 b extends through opening 206 and engages upper portion 100 a . in this manner , manifold 100 mounts within unit 200 but leaves external thereof the flange portion 146 c . filter unit 146 may be easily withdrawn from upper portion 100 a when sufficient time has elapsed or contaminants accumulated . a replacement filter unit 146 ′ may then be mounted to upper portion 100 a of manifold 100 . each ball - type check valve 140 includes a corresponding ball 141 resting within a conical depression 143 . any airflow through a given valve 140 in the direction of the corresponding inlet 138 immediately drives ball 141 into the well of depression 143 thereby blocking further airflow . thus , each valve 140 is a unidirectional valve permitting airflow only in the direction from an inlet 138 into manifold 100 . as may be appreciated , a variety of unidirectional valve devices may be used . each filter unit 146 includes at its proximal end an annular indent 147 . an o - ring 149 rests in an opening 151 of upper portion 100 a . more particularly , a sleeve 152 captures o - ring 149 within an opening 15 of upper portion 100 a . sleeve 152 permanently attaches to portion 100 and creates in conjunction with opening 151 an annular groove holding o - ring 149 . stem 146 a at its proximal end passes through sleeve 152 and engages at its annular indent 147 the o - ring 149 . this secures filter unit 146 to upper portion 100 a of manifold 100 and also establishes an air tight seal therebetween . thus , air entering the interior or common manifold area 142 of manifold 100 passes out of upper portion 100 a only by way of filter unit 146 and eventually out of filter unit 146 only by way of filter element 146 a thereof . fig3 illustrates a bottom view of upper portion 100 a only . fig3 illustrates opening 151 in portion 100 a without the sleeve 152 attached therein . as best seen in fig3 common manifold space 142 exists at the terminal portion of opening 151 and provides fluid communication with the remainder of common manifold space 142 . fig3 also illustrates each of the four inlets 138 , individually 138 a - 138 d , for manifold 100 . each inlet 138 a communicates with a corresponding one of the ball - type check valves 140 , individually 140 a - 140 d . fig3 also illustrates opening 208 passing through upper portion 100 a and permitting attachment to floor 202 as illustrated in fig2 . fig4 illustrates a top view of upper portion 100 a with a cover 500 ( fig5 ) removed from upper portion 100 a . as seen in fig4 the conic depressions 143 , individually 143 a - 143 d , open at a most - deep plane 400 within portion 100 a . at the well of each conic depression 140 , a conduit 402 , individually 402 a - 402 d , fluidly couples to the corresponding one of inlets 138 , individually 138 a - 138 d , respectively . an offset shelf 406 surrounds the periphery of plane 400 and receives cover 500 ( fig5 ) thereon . cover 500 captures balls 141 ( not shown in fig4 ) within depressions 143 as well as closes and defines a boundary of manifold space 142 . thus , opening 151 fluidly couples by way of manifold space 142 to the conic depressions 143 and , by way of conduits 402 , to the inlets 138 . with balls 141 in place , however , fluid flow within upper portion 100 a is unidirectional , i . e ., from inlets 138 into common manifold space 142 and thereafter out through opening 151 and filter unit 146 into ambient air space 144 . fig5 illustrate cover 500 including an aperture 208 ′ corresponding in position to aperture 208 of upper portion 100 a . cover 500 attaches to and seals relative to shelve 406 ( fig4 ). fig2 also illustrates placement of sound suppression element 170 within the conduit 146 d of unit 146 . element 170 may be provided as a piece of open - cell foam admitting passage of air therethrough and suppressing sound emanation , e . g ., exhaust and ball 141 rattle , from manifold 146 . slow speed handpieces as well as ultrasonic devices all typically couple into the same exhaust system . such slow piece devices and ultrasonic devices don &# 39 ; t collect significant bio - contaminants but they do carry oil in the return line . these devices can operate on the same exhaust manifold of the present invention to prevent oil contamination of the environment . it will be appreciated that the present invention is not restricted to the particular embodiment that has been described and illustrated , and that variations may be made therein without departing from the scope of the invention as found in the appended claims and equivalents thereof .
an exhaust manifold for a dental handpiece system receives at an inlet thereof return air flow provided by a dental handpiece . a unidirectional valve couples the inlet to a common manifold space which in turn couples to ambient air by way of a filter . by applying filtration on the backside of the unidirectional valve , air entering the common manifold space cannot thereafter reenter the return air conduit and thereby contaminate the same handpiece or other handpieces in a multiple handpiece system . a replaceable filter unit avoids accumulated debris and promotes better sanitary conditions .