referring to fig1 , one exemplary embodiment of a suction regulator r is shown . the suction regulator r includes a body 19 defining an outlet port 1 that is configured to be coupled to a source of suction , an inlet port 2 that is configured to be in fluid communication with a patient via a conduit ( not shown ), and a fluid passageway 3 defined between the outlet port 1 and inlet port 2 . a valve seat 11 is defined along the fluid passageway 3 . although not shown , valve seat 11 may also be a separate component assembled with fluid passageway 3 . a valve 15 ( also referred to herein as a stem ) is movable with respect to valve seat 11 for selectively exposing inlet port 2 to the source of suction to draw fluid flow 25 through inlet port 2 and fluid passageway 3 under the force of suction . the valve 15 optionally includes a seal 10 for sealing contact with valve seat 11 . in one exemplary use of the suction regulator r illustrated in fig1 , unregulated hospital central suction is applied to regulator r through outlet port 1 drawing fluid 25 through the inlet port 2 connected to the patient . the reduction in pressure ( i . e ., increase in suction ) in fluid passageway 3 also encourages airflow 4 ( depicted by arrows ) through a gap 12 provided between body 19 and housing 40 . the housing 40 is threadedly engaged onto body 19 and moveable with respect thereto . although not shown , housing 40 and body 19 may be integral components . airflow 4 is drawn through an orifice 13 and into a regulating chamber 5 . the regulating chamber 5 is defined in the housing 40 . in operation , regulating chamber 5 maintains a reduced pressure signal . this reduced pressure signal is possible since the clearance afforded by air gap 16 formed by the clearance between the outer diameter of stem 15 and the inner diameter of threaded sleeve 14 is sufficiently larger than the open area of orifice 13 . diaphragm 7 is positioned between regulating chamber 5 and atmospheric reference 6 . the reduction in pressure in regulating chamber 5 causes diaphragm 7 to exert a force against piston 8 urging valve 15 toward valve seat 11 . counterbalancing the force of the diaphragm is the force of a resilient element 9 , which may optionally be a spring . diaphragm 7 will continue to move until equilibrium has been reached with the spring force exerted by resilient element 9 . in the process of moving piston 8 , seal 10 translates toward or in contact with seat 11 to stop the reduction in pressure caused by outlet port 1 . regulated suction is then delivered to the patient connection p via inlet port 2 . the arrangement of valve 15 , valve seat 11 , resilient element 9 , piston 8 and diaphragm 7 of the suction regulator r may also be referred to herein as a means for regulating suction within the fluid passageway 3 . it should be understood by one skilled in the art that alternative means exist for regulating suction within a fluid passageway . accordingly , the invention is not limited to the above arrangement of components . the suction output of the regulator is varied by changing the relative position of the housing 40 by rotating the housing 40 along at least a portion of the length of the threaded sleeve 14 , thus changing the load on resilient element 9 and consequently translating the valve 15 with respect to the valve seat 11 . the flow requirements of inlet port 2 will affect the negative pressure signal in the fluid passageway 3 , thus influencing the reduced pressure in regulating chamber 5 . this change in pressure will in turn effect the movement of seal 10 in relation to valve seat 11 . airflow 4 through orifice 13 continuously washes the internal surfaces of regulating chamber 5 when the valve 15 is separated from the valve seat 11 . this airflow 4 travels between threaded sleeve 14 and valve 15 to provide a clean wash of air in gap 16 . mechanical barrier 17 , also referred to herein as a shroud , protects the exposed surfaces of valve 15 when any foreign material is propelled into inlet port 2 with velocity sufficient to enter this area . for proper regulation , valve 15 slides freely , i . e ., without significant resistance , within the interior of threaded sleeve 14 . any material buildup of foreign material on the interface of the mating surfaces of the valve 15 and sleeve 14 would impede free relative motion of the valve 15 . threaded sleeve 14 contains a smaller diameter section 20 which allows for the full range of motion between valve 15 and threaded sleeve 14 , minimizing the possibility of exposing the interface of these two parts to the ingress of foreign materials . the open area between barrier 17 and the smaller diameter section 20 is similar to the open area of the air gap between valve 15 and threaded shaft 14 . this similarity of areas ensures a consistent one way purging airflow 4 providing for only clean air to travel in these air spaces . although not shown , a filter , such as a felt ring , may be included in the regulator r to filter the airflow to minimize airborne particles . as parts 7 , 8 , 10 and 15 are acted upon by the relative pressure changes in regulation chamber 3 ; volume in regulating chamber 5 will increase and decrease causing the potential for airflow 4 to reverse direction . calibrated airflow 4 through gap 16 is sufficiently great enough to offset the speed of movement of parts 7 , 8 , 10 and 15 thereby making it possible to ensure airflow 4 only provides a one way wash of clean air over these components . the regulating means is preferably defined by parts 5 , 6 , 7 , 9 , 10 , 11 , 15 . additionally , the airflow 23 along the outer diameter of the valve 15 functions as an air bearing to minimize sliding friction . in a static condition , with little flow demands from patient p via inlet port 2 , the force of seal 10 upon seat 11 is aided by the shear of airflow 23 along shaft 15 . the force of seal 10 upon seat 11 is also aided by the reversal of direction of airflow 23 as impact head on face 22 . these two additional forces acting upon seal 10 help counteract the change in regulated pressure , spike or droop , as flow varies with change in the demands from patient p upon the system . the regulator r includes a means 45 for indicating a level of suction within fluid passageway 3 . the suction indication means 45 may be a pressure gauge 45 mounted to body 19 , for example , as illustrated in fig1 . two orifices 42 and 43 formed in body 19 permit the introduction of atmospheric airflow 44 through gauge 45 and into fluid passageway 3 under the source of suction . in operation , normal variation in the level of regulated suction will result in changes in the gauge reading of gauge 45 . movement of gauge 45 is caused by changes in the relative volume of air in gauge 45 . reduction in volume of the airspace causes atmospheric air to enter fluid passageway 3 , while increases in volume of this airspace causes atmospheric air to enter gauge 45 . another exemplary embodiment of a suction regulator is illustrated in fig2 . according to this exemplary embodiment , the regulator r includes a body 125 defining an outlet port 100 that is configured to be coupled to a source of suction ( not shown ), an inlet port 200 that is configured to be in fluid communication with the patient ( not shown ), and a fluid passageway 103 defined between outlet port 100 and inlet port 200 . a valve seat 111 is defined along or positioned within fluid passageway 103 . a valve 126 is movable with respect to valve seat 111 for exposing inlet port 200 to the source of suction . the valve 126 optionally includes a seal 110 at its sealing end for mating with valve seat 111 . an insert 120 is positioned within fluid passageway 103 for directing fluid flow 104 into fluid passageway 103 . the insert 120 includes a helical channel for promoting centrifugal separation of the particles and aerosols of fluid flow 104 within fluid passageway 103 , as best described with reference to fig3 a - 3 c . the insert 120 further comprises an air passageway 122 that is positioned in fluid communication with means 121 for indicating a level of suction within fluid passageway 103 . the suction indication means 121 may be a pressure gauge 121 mounted to body 125 , for example , as illustrated in fig2 . the suction indication means could also be an analog gauge known in the art comprised of a copper bellows . similar to the previous embodiment , two orifices 123 and 129 formed in body 125 permit the introduction of atmospheric airflow 124 through gauge 121 and into fluid passageway 103 under the source of suction . in operation , normal variation in the level of regulated suction will result in changes in the gauge reading of gauge 121 . movement of gauge 121 is caused by changes in the relative volume of air in gauge 121 . reduction in volume of the airspace causes atmospheric air to enter fluid passageway 103 , while an increase in volume of this airspace causes atmospheric air to enter gauge 121 . in prior art suction regulators , an increase in volume of the gauge 121 would draw fluid from passageway 103 and the patient circuit into gauge 121 , consequently introducing contaminants into the pressure gauge . thus , the benefit afforded by an isolation means may also be applied to the suction indication means of the device as well . the air passageway 122 of insert 120 faces downstream of the fluid flow 104 to minimize entrainment of fluids into the gauge 121 . insert 120 may be constructed to be removable and replaceable in the event of fluid intrusion to simplify any necessary cleaning processes . furthermore , gauge 121 is oriented in a vertical self - draining orientation to facilitate cleansing and flushing . the introduction of atmospheric air into orifice 123 allows for any increase in the volume of gauge 121 to be made up of clean atmospheric air , as opposed to air from the patient circuit . the valve 126 is positioned through an aperture ( not shown ) provided in a diaphragm 107 . diaphragm 107 is positioned between fluid passageway 103 and atmospheric reference 106 . the diaphragm 107 is adapted to flex in response to a pressure differential on its opposing sides between fluid passageway 103 and atmospheric reference 106 , as should be understood by one skilled in the art . the valve 126 is coupled to diaphragm 107 , such that flexion of diaphragm 107 induces translation of valve 126 with respect to valve seat 111 . flexion of the diaphragm is counterbalanced by a spring loaded piston 115 , extending from , or mounted to , valve 126 . the spring loaded piston 115 is positioned within a regulating chamber 105 . the diaphragm 107 separates fluid passageway 103 from regulating chamber 105 to prevent or limit deleterious fluid from entering regulating chamber 105 and contaminating the components positioned within chamber 105 , including spring loaded piston 115 . in another exemplary embodiment not illustrated herein , the diaphragm and spring arrangement shown in fig2 may be replaced by a bellows . a first resilient element 128 ( in the form of a spring , for example ) biases piston 115 and valve 126 in a direction away from valve seat 111 . a second resilient element 109 ( in the form of a spring , for example ) that is positioned on the opposite side of piston 115 , removes the preload of first resilient element 128 for biasing piston 115 and valve 126 in a direction toward valve seat 111 . an adjustable threaded sleeve 119 is rotatably coupled to body 125 for adjusting the compression force of second resilient element 109 against piston 115 . the arrangement of valve 126 , valve seat 111 , resilient elements 128 and 109 , piston 115 and diaphragm 107 of the suction regulator r may also be referred to herein as a means for regulating suction within the fluid passageway 103 . it should be understood by one skilled in the art that alternative means exist for regulating suction within a fluid passageway . accordingly , the invention is not limited to the above arrangement of components . according to one exemplary use of the suction regulator r illustrated in fig2 , unregulated wall suction enters regulator r through inlet port 100 . fluid passageway 103 undergoes a reduction in pressure encouraging fluid flow 104 ( depicted by arrows ) through inlet port 100 . fluid flow 104 relays the reduced pressure signal to regulating chamber 105 via diaphragm 107 . this reduced pressure signal is possible since a diaphragm will transmit a change in pressure with low resistance and the clearance afforded by air gap 116 formed by the clearance between the outer diameter of valve 115 and the inner diameter of sleeve 114 allows motion of the valve . the clearances provide the performance attributes previously described for an air curtain isolation . the reduction in pressure in chamber 105 causes diaphragm 107 to exert a force against piston 115 . counterbalancing the force of the diaphragm is the force of resilient element 128 , which may optionally be a compression spring . diaphragm 107 will continue to move until equilibrium has been reached with the force exerted by resilient element 128 . in the process of moving piston 115 , seal 110 should preferably come in to contact with seat 111 to stop the reduction in pressure caused by high negative pressure at outlet port 100 . regulated suction is then delivered to the patient via inlet port 200 . the suction output is varied by changing the relative position of the spring seat by rotating the threaded sleeve 119 , thus changing the load on resilient element 109 , as described previously . the flow requirements of inlet port 200 will affect the negative pressure signal in fluid passageway 103 thus influencing the reduced pressure in chamber 105 . this change in pressure will in turn effect the movement of seal 110 in relation to seat 111 . referring to the fig3 a - 3 c , detailed views of insert 120 of fig2 are illustrated . fig3 a is a top plan view of insert 120 . the insert 120 includes an inlet 201 ( shown in broken lines ) for receiving fluid flow 104 from inlet port 200 that is connected to the patient . fluid flow 104 travels through a helical channel 202 that extends between inlet 201 and thru - hole 207 . although not shown in this view , valve 126 is slideably positioned through thru - hole 207 ( see fig2 ). the helical channel 202 promotes centrifugal separation of the particles and aerosols of fluid flow 104 within fluid passageway 103 , as previously described above . fig3 b is a cross - sectional view of insert 120 taken along the lines a - a of fig3 a . as best shown in this view , air passageway 122 is disposed along the height dimension of insert 120 . the air passageway 122 is positioned in fluid communication between fluid passageway 103 and pressure gauge 121 . an orifice 204 is defined at the end of air passageway 102 for delivering atmospheric air into fluid passageway 103 . fig3 c is a side view of insert 120 of fig3 a illustrating inlet 201 of helical channel 202 . according to another aspect of the invention , the suction regulator may be an electric suction regulator 300 , as shown schematically in fig4 . an electric suction regulator 300 may be comprised of a pressure transducer 302 to sense the level of suction in the circuit , and an actuation means 304 , such as a motor or solenoid , to power a valve 306 that adjusts the flow of suction delivered to the patient 308 from the central suction supply 310 . the actuation means 304 operatively turns the source of suction on and off in response to downstream conditions in the circuit , as determined by a control algorithm 320 . similar to the prior embodiments disclosed herein , the means for regulating suction within the fluid passageway is isolated from the fluid passageway of the regulator . specifically , one side of the pressure transducer 302 may be isolated from contaminants in the fluid flow delivered by the patient 308 by means of an transducer isolation means 312 , such as an elastomeric member , or low durometer elastomeric covering . the opposing side of the pressure transducer 302 may be referenced to atmospheric air 314 , as shown . given the construction of silicon wafer based pressure transducers , minimal displacement is needed to determine a change in pressure , and fluid flow based on this displacement is negligible . the actuation means 304 may be isolated from the fluid path by an actuator isolation means 318 . the actuator isolation means 318 may be a diametric seal , elastomeric film , o - ring , u - cup or a wiper seal positioned over the shaft of the actuation means 304 ( e . g ., motor ), for example . in this way the power of the actuation means 304 would not be adversely affected by the presence of contaminants in the patient circuit . the actuation means 304 in turn could adjust the flow of the circuit in a variety of means . the control algorithm 320 compares user controlled set - point 316 with the level of suction in the circuit in the regulator ( as determined by the pressure transducer 302 ). the flow of suction delivered to the circuit may be adjusted via actuation means 304 according to the computations of control algorithm 320 . the control of the actuation means 304 can be via linear approximation of a seal to a seat , as in the mechanical analog , or alternatively may be achieved with a solenoid type valve displaying simple on / off control , in concert with a pwm signal to regulate the intended output . although the invention is illustrated and described herein with reference to specific embodiments , the invention is not intended to be limited to the details shown . rather , various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention .
a suction regulator for controlling a level of negative pressure in a system in which compensatory clean airflow is used to isolate a control device for regulating suction delivered to a patient is disclosed . the regulator comprises an inlet ; an outlet ; a controller for controlling the suction delivered to the inlet ; and a barrier for isolating the controller from the inlet .