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This is the "Teledyne" style sensor. They make me nevous still. The "restive" types are accurate to about 2%, The paramagnetic type are accurate to about .1%. New teledyne sensor is about $90. Paramagnetic types are very expensive , however out of the reach of poor divers like me. This has all been discussed before as I asked for info on oxygen analyzers last fall, so I won't go into lots of detail. It should be in the archives. >---------- >From: rfarb[SMTP:rfarb@na*.ne*] >Sent: Tuesday, March 26, 1996 7:18 PM >To: Alex Varouxis >Cc: techdiver@terra.net >Subject: Re: Rebreather Question > >Alex, in the Biomarine 155 there are three oxygen sensors. All this >information comes from a manual that Biomarine supplied with the unit. > >Their sensor is made up of a lead anode, a gold cathode, a teflon >diffusing barrier, a KOH electrolyte bath, and an external load >resistor. >The gold cathode is the reaction site for the reduction of oxygen >molecules into hydroxyl ions; gold is not consummed in the reaction. >The >hydroxyl ions react with the lead electrode, forming lead oxide and >releasing electrons. Electron flow between anode and cathode is through >an >external resistor, producing an output voltage. Output voltage is a >function of the number of oxygen molecules reduced at the gold >electrode. >Sensor output is 18-21mv in air at 1 atm; 1 atm pure O2 would read >50-99 >mv. The unit's primary display (worn on right hand) has a pO2 section >that >has five illuminated sequential letters and numbers to indicate normal, >high or low levels of oxygen according to the calibration. The unit can >be >calibrated from 0.7 to 1.3 pO2. The unit's secondary gauge (clipped to >D >ring on BC) is an analog meter (digital in MK16) which displays sensor >output and battery voltage. Individual sensor readouts are obtained by >turning a knob to sensor 1, 2, 3 dial position. Each sensor generates >sufficient electrical output to activate the meter and does not require > >electronic amplification. Is this what you mean by, "how are they >read"? >If not, then the quick answer is, I read them with my eyes. I can do >this >in the dark because the secondary gauge has a tritium face that >glows in the dark (inset so that no glow escapes; with a velcro'd lid). >Rod > >On Tue, 26 Mar 1996, Alex Varouxis wrote: > >> How many PO2 sensors are used in a rebreather and how are they read? >> >> -Alex >> >> -- >> Send mail for the `techdiver' mailing list to `techdiver@terra.net'. >> Send subscription/archive requests to `techdiver-request@terra.net'. >> >-- >Send mail for the `techdiver' mailing list to `techdiver@terra.net'. >Send subscription/archive requests to `techdiver-request@terra.net'. >
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