a method and device for practicing the method are provided to sense the presence of or the absence of pressure for a medical oxygen tank of the type used by patients who require additional oxygen . referring now to fig1 : the device 0 is comprised of : a 1 . 5 volt to about 12 volt battery 1 , preferably 9 volt , having positive (+) terminal and a negative (−) terminal ; power on / off switch 2 ; normally closed high pressure switch 3 , having input terminal 3 a , output terminal 3 b and internal electrical contacts ; visual alarm 4 of the led type , preferably red , having input 4 a and output 4 b , audible alarm 5 of the magnetic buzzer or piezo type , preferably magnetic buzzer type , capable of producing an audible sound of about 80 db to about 95 db , having input 5 a and output 5 b with regard to safe operation of the device at high pressure , about 2 , 800 psi for a full oxygen tank ; normally closed high pressure switch 3 is specified to be “ oxygen clean ” and having an operating pressure of at least 3000 psi , proof pressure of about 3500 psi and burst pressure of about 5000 psi where the internal electrical contacts close when pressure drops to a predetermined limit . such a switch can be purchased from mamco precision switches , 147 river street , oneonta , n . y . 13820 . to effect the operation of device 0 : input terminal 3 a of high pressure switch 3 is electrically connected through power on / off switch 2 to the positive terminal of battery 1 ; output terminal 3 b of normally closed high pressure switch 3 is connected to input 4 a of visual alarm 4 and to input 5 a of audible alarm 5 ; output 4 b of visual alarm 4 and output 5 b of audible alarm 5 are connected to the negative terminal of battery 1 . finally device 0 is affixed to an oxygen regulator such as probasics model # 88 - 8emmr by screwing male ⅛ inch npt connector 3 c of high pressure switch 3 into an “ oxygen clean ” t connector having two female ⅛ inch npt connectors and one male ⅛ inch npt connector as shown in fig3 . connector 3 c is screwed into one of the female ⅛ inch connectors of the t ; preferably the female connector perpendicular to the male ⅛ inch npt connector of the t . next the oxygen gauge is removed from the oxygen regulator and screwed into the remaining female ⅛ inch npt connector of the t . the t , now having the oxygen pressure gauge of the oxygen regulator and device 0 attached , is affixed to the regulator by screwing the male ⅛ inch npt connector of the t into the regulator &# 39 ; s female ⅛ npt available as a result of removing the oxygen pressure gauge . the oxygen regulator ; now equipped with a gauge and device 0 is then attached to a medical oxygen tank or cylinder using standard practices . when power on / off switch 2 is in the “ on ” position ; visual alarm 4 and audible alarm 5 are activated ; producing continuously , a red visual alarm and a loud buzzing alarm which is audible indoors to about 50 feet . when the regulator is turned on ; the electrical contacts within normally closed high pressure switch 3 open as a result of the pressure of the oxygen tank exceeding a preset limit , preferably about 500 psi and visual alarm 4 and audible alarm 5 are deactivated . when the oxygen tank &# 39 ; s pressure , as a result of oxygen usage by the patient , drops to a preset limit , preferably 500 psi ; the electrical contacts within normally closed high pressure switch 3 close and visual alarm 4 and audible alarm 5 are activated to give continuous alarm until the oxygen tank is replaced by a caregiver . referring now to fig2 , depicting a second embodiment : the device 0 is comprised of : a 1 . 5 volt to about 12 volt battery 1 , preferably 9 volt , having positive (+) terminal and a negative (−) terminal ; power on / off switch 2 ; normally closed high pressure switch 3 , having input terminal 3 a , output terminal 3 b and internal electrical contacts ; visual alarm 4 of the led type , preferably red , having input 4 a and output 4 b , audible alarm 5 of the magnetic buzzer or piezo type , preferably piezo type , capable of producing an audible sound of about 80 db to about 95 db , having input 5 a and output 5 b and microcontroller 6 having input 6 a , output 6 b , and pin outs 6 c , 6 d , 6 e , 6 f . with regard to safe operation of the device at high pressure ; normally closed high pressure switch 3 is specified to be “ oxygen clean ” and having an operating pressure of at least 3000 psi , proof pressure of about 3500 psi and burst pressure of about 5000 psi where the internal electrical contacts close when pressure drops to a predetermined limit . such a switch can be purchased from mamco precision switches , 147 river street , oneonta , n . y . 13820 . with regard to microcontroller 6 , a subroutine built in at manufacture , causes audible alarm 5 to “ chirp .” each chirp consists of a fixed on - time and a fixed off - time . these on - and off - times are determined experimentally , and are subjectively chosen to make the audible alarm as noticeable as possible . in like manner a built in subroutine causes visual alarm 4 to flash at a predetermined rate , such as once a second to make the visual alarm as noticeable as possible . such microcontrollers are available in the marketplace ; one manufacturer being maxim integrated products , inc . 120 san gabriel drive sunnyvale , calif . 94086 usa to effect the operation of device 0 : input terminal 3 a of high pressure switch 3 is electrically connected through power on / off switch 2 to the positive terminal of battery 1 ; output terminal 3 b of normally closed high pressure switch 3 is electrically connected to input 6 a of microcontroller 6 ; pin out 6 c of microcontroller 6 is electrically connected to input 4 a of visual alarm 4 ; pin out 6 d of microcontroller 6 is electrically connected to output 4 b of visual alarm 4 ; pin out 6 e of microcontroller 6 is electrically connected to input 5 a of audible alarm 5 ; pin out 6 f of microcontroller 6 is electrically connected to output 5 b of audible alarm 5 and output 6 b of microcontroller 6 is electrically connected to the negative terminal of battery 1 . finally device 0 is affixed to an oxygen regulator such as probasics model # 88 - 8emmr by screwing male ⅛ inch npt connector 3 c of high pressure switch 3 into an “ oxygen clean ” t connector having two female ⅛ inch npt connectors and one male ⅛ inch npt connector as shown in fig3 . connector 3 c is screwed into one of the female ⅛ inch connectors of the t ; preferably the female connector perpendicular to the male ⅛ inch npt connector of the t . next the oxygen gauge is removed from the oxygen regulator and screwed into the remaining female ⅛ inch npt connector of the t . the t , now having the oxygen pressure gauge of the oxygen regulator and device 0 attached , is affixed to the regulator by screwing the male ⅛ inch npt connector of the t into the regulator &# 39 ; s female ⅛ npt available as a result of removing the oxygen pressure gauge . the oxygen regulator ; now equipped with its pressure gauge and device 0 , is then attached , using standard practices , to a medical oxygen tank or cylinder . when power on / off switch 2 is in the “ on ” position ; microcontroller 6 is activated through normally closed high pressure switch 3 and causes visual alarm 4 and audible alarm 5 to be activated in an intermittent manner directed by the microcontroller 6 subroutine . when the regulator is turned on ; the electrical contacts within normally closed high pressure switch 3 open as a result of the pressure of the oxygen tank exceeding a preset limit , preferably about 500 psi and microcontroller 6 is deactivated causing visual alarm 4 and audible alarm 5 to be deactivated . when the oxygen tank &# 39 ; s pressure , as a result of oxygen usage by the patient , drops to a preset limit , preferably 500 psi ; the electrical contacts within normally closed high pressure switch 3 close and microcontroller 6 is activated and causes visual alarm 4 and audible alarm 5 to be activated in an intermittent manner directed by the microcontroller 6 subroutine until the oxygen tank is replaced by a caregiver . the method and embodiments of the current invention have been - described in connection with providing a visual alarm and an auditory alarm for empty oxygen bottles such as used by medical patients thereby the risk of a life threatening peril . all such modifications and alterations should be apparent to those skilled in the art as well as all such configurations and embodiments of the method and are deemed to be encompassed within the spirit and scope of the claims as set forth below .
a cost effective method is provided for determining empty and / or near empty medical and other medical emergency oxygen tanks employing a single , simple device for practicing the method , comprised of 5 or 6 readily obtainable components , to issue visual and audible alarms when the oxygen pressure of a medical oxygen tank has decreased to a predetermined pressure , deemed too low to provide the needed and / or prescribed oxygen flow rate to a patient to alert medical personnel and other caregivers that it is time to replace the tank in with a full tank .