exhaust gas analyzer
#21
08-16-2010 | 06:33 PM
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From: Sonoran Desert, Arizona
On this one I think I am correct in they read pressure of oxygen. more accuratly they read partial pressure of oxygen. Which at atmoshperic pressure is also %Oxygen
We use them in "Nitrox Analyzers" to determine the oxygen percentage in a divers supply tank. There the display is calibrated so the readout is .21 for air(21% Oxygen .79%Nitrogen aproximatly) & 1.00 for 100% oxygen. But we also use them for reading the partial pressure of oxygen in closed loop rebreathers. In that case the % ratio of oxygen in the mixture may stay the same but the pressure increases as you go deeper. For example at 100' the pressure is 4 times what it was at the surface so the cell will output 4 times the voltage which will cause the display to read .84 even if the % is still 21%. When tuneing a vehicle of course you really are concerned with what is happening at standard atmospheric pressure so I guess commen terminoligy is in %. I show my students that pressure affects the reading of the analyzers we use by blocking the exh flow a little and allwing the pressure on the cell membrane to increase a little(too much will damage the cell) this causes the reading to increase slightly. The reson for this demonstration is to demonstrate why it is more accurate to use a regulator and an oriface to give consistant flow rates and pressure on the cell for given tank pressures. The other option commenly used is an oriface held up to a scuba tank valve which will flow more or less depending on how much pressure is in the tank or how tightly you hold the oriface to the valve.
Sorry got on a ramble but just thought I would throw out some FYI where I actually have some experiance.
I think I may look for the analyzer flying fin has.
Do you guys think you could simulate load by sitting on the bike with front tire against a wall and slipping the clutch in gear? I think if you just did it a bit you should not ruin the clutch and it would give you an idea of work under load.
We use them in "Nitrox Analyzers" to determine the oxygen percentage in a divers supply tank. There the display is calibrated so the readout is .21 for air(21% Oxygen .79%Nitrogen aproximatly) & 1.00 for 100% oxygen. But we also use them for reading the partial pressure of oxygen in closed loop rebreathers. In that case the % ratio of oxygen in the mixture may stay the same but the pressure increases as you go deeper. For example at 100' the pressure is 4 times what it was at the surface so the cell will output 4 times the voltage which will cause the display to read .84 even if the % is still 21%. When tuneing a vehicle of course you really are concerned with what is happening at standard atmospheric pressure so I guess commen terminoligy is in %. I show my students that pressure affects the reading of the analyzers we use by blocking the exh flow a little and allwing the pressure on the cell membrane to increase a little(too much will damage the cell) this causes the reading to increase slightly. The reson for this demonstration is to demonstrate why it is more accurate to use a regulator and an oriface to give consistant flow rates and pressure on the cell for given tank pressures. The other option commenly used is an oriface held up to a scuba tank valve which will flow more or less depending on how much pressure is in the tank or how tightly you hold the oriface to the valve.
Sorry got on a ramble but just thought I would throw out some FYI where I actually have some experiance.
I think I may look for the analyzer flying fin has.
Do you guys think you could simulate load by sitting on the bike with front tire against a wall and slipping the clutch in gear? I think if you just did it a bit you should not ruin the clutch and it would give you an idea of work under load.
The type of sensor used in automotive emission analyzers are of the electro-chemical type (galvanic). They can only be used at pressures near atmospheric pressure.
The type of sensor in the A/F meters is yet a third type. They are zirconia sensors. This is the type used in vehicle exhausts. They need to be heated to work.
Ron
#23
08-17-2010 | 01:58 AM
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Posts: 805
From: Guam
R Ron
Thanks for the clarification. I have allways refered to our sensors as "Galvanic Fuel Cell's" They can be used at higher pressures but the entire sensor has to be pressureized not just the side that is sensing the breathing gas. Also they like people can only adjust to slower pressure changes, usuall not a problem. Just looked them up and theya re called Hersch cell's
So it looks like I need to buy not build. Oh well gives me more time to earn the $ to buy the analyzer!
Cheers Jim
Thanks for the clarification. I have allways refered to our sensors as "Galvanic Fuel Cell's" They can be used at higher pressures but the entire sensor has to be pressureized not just the side that is sensing the breathing gas. Also they like people can only adjust to slower pressure changes, usuall not a problem. Just looked them up and theya re called Hersch cell's
So it looks like I need to buy not build. Oh well gives me more time to earn the $ to buy the analyzer!
Cheers Jim
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