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Patrick, I think we are saying basically the same thing. I've never owned an OMS O2 analyzer but a friend said that the OMS brochure said the sensor lasted forever, that is what I was referring to. I guess it's a justification for the high price. I think their sensor has a little holder that seals the sensor head. If I was given bad information I apologize. I too think its BS that a sensor never goes bad. This isn't Star Trek, fuel cells don't last forever or recharge themselves all by themselves.... :) The "Spectrum Oxygen Analyzer" I gave the Web site for (http://www.oxygenanalyzer.com/) uses as standard the MSA 406931 30 second sensor (replacement cost $49) and for $10 more will send the Teledyne R-17A 10 second sensor (you guessed it, replacement cost $59). I think these sensors are extremely competitive. I'm pretty sure that if you for whatever reason liked another sensor better you could configure the unit to use that type. If you need/want that you can contact them directly (they are nice people), I know they also use the Maxtec sensor. My sensor is 3 years old and I'm going to replace it next year. Don't want to go to analyze tanks and have it dead. Better save than sorry, $49 every 3 years isn't going to break my bank regardless if the sensor is going or not. Art. -----Original Message----- From: Patrick Duffy [mailto:pduffyca@ea*.ne*] Sent: Tuesday, October 23, 2001 12:45 PM To: Paltz, Art Cc: rmmacleod@ac*.ca*; techdiver@aquanaut.com Subject: Re: O2 Analyzer Art, All O2 analyzers perform the same function and most all have similar (and often identical) components. Usually the higher end units have sealed potentiometers, on/off switches and electronics enclosures and have a more expensive panel meter. One question often over looked is the cost of a replacement sensor. A number of manufacturers have chosen to use a high output sensor in their designs which results in a more expensive sensor. Others even go as far as making a proprietary sensor shell to force you to buy their sensor at inflated prices. Then there are the mfgs that put the least expensive sensor in the unit in an effort to keep the total price of the analyzer down. Some sensors do have a shorter life than others (read the specs if they will tell you the sensor mfg) as well as different response times. I've even seen dive equipment manufacturers state the sensor will last longer than the sensor manufacturer claims it will (figure that one out). There are many sensor manufacturers out there, making a sensor is not too hard, making a sensor that is consistent in performance is the difficult part. I've never heard of a sensor lasting forever, they are basically batteries that produce mv based on the amount oxygen exposure. The greater the PPO2 and length of exposure, the shorter the life will be. Replacing a sensor in an oxygen analyzer is not needed until it is dead. In most cases you'll be able to calibrate it today, but will not tomorrow. The only divers that should seriously consider scheduled replacement are those diving rebreathers. Putting the analyzer and sensor in a box is wise for protection, but it will not extend the sensor life ... too much space. Along the subject of placing caps on the sensor, they cut off the amount of oxygen and do drop the mv significantly. I placed a cap over a new sensor I am testing the other day. The sensor was measured at 10.4mv. I placed a cap on the sensor and over a 4 day period the sensor mv dropped until it reached 1.4mv. At that time, I took off the cap to see how fast the sensor would recover ... it came back to 10.3mv in about three seconds. I checked it about 20 minutes later and it was back to 10.4mv. This is a new sensor that is not presently available, and I know not every sensor make will have this response/recovery time. Most require much more recovery time. Regards, Patrick -- OxyCheq ... the diver's source for oxygen sensors http://oxycheq.com Art.Paltz@R2*.CO* wrote: > I bought from http://www.oxygenanalyzer.com/ > > In my opinion they are all pretty much the same except for the price. If > you think about it, all it is, is a panel meter (volt meter) and an O2 > sensor. As far as I know all panel meters are pretty much the same in the > range we are talking (1-2%). If we were measuring where millionths of a > volt mattered then there would be a difference. I don't know for sure but > even a one percent reading for the oxygen content is only like a millivolt > and I don't think that's too hard to read for most volt meters. You're > variance is really going to be in the sensor which if you read the specs is > pretty much a percent or 2. I don't know the difference in the sensors, > you'd have to ask someone else but again, for our purpose, they are all > pretty much the same as long as kept relatively fresh. You should be > selecting an O2 content (Po2) that is not going to kill you and is way in > the save zone. If you are pushing really hot bottom or decompression mixes > then you probably should be changing the sensor all the time as they do > degrade over time (should you choose to be this dumb). If you have some > reason that I can't really think of where you need to use these type of > mixes you might want to invest in a spectrum analyzer cause being extremely > accurate probably matters. > > The one at the above site is pretty much the same thing as the one you can > build in the O2 hackers handbook. If you are like me and bought all the > parts (minus sensor) to build one yourself but are too lazy to do it, then > this is a good deal for you. > > I wouldn't believe the claims of sensors lasting forever on some analyzers. > They all go! It's just that I think some of them have a cap to cap off the > sensor when not in use so it stops degrading until the next use. You can do > this yourself by putting the analyzer and sensor in an air tight pelican > box.... A lot cheaper and you should probably have the analyzer/sensor in a > box anyway so it's doesn't break it..... > > Just my opinion, hope it helps. > Art. > > -----Original Message----- > From: The McLeods [mailto:rmmacleod@ac*.ca*] > Sent: Sunday, October 21, 2001 8:16 PM > To: techdiver > Subject: O2 anylizer > > Hi list,I'm looking to buy a new O2 anylizer.I'd like some opinions on which > one is best,best buy,best made ect.Are all the makes available in Canada,how > much are replacement sensor's and what are the best features.Thank's in > advance,Randy > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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