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Right-o there buddy. That would explain why how everyone here (everytime), when they put 545 psi of oxygen in a tank (with a reasonably accurate pressure gauge) and top it off to 3300 comes out with a measured 34% O2. Boy, you're right. These things just don't work worth a damn. Now I can't go diving today because of this. You have ruined my day. Geeze, when am I going to get around to filtering these AOL trolls.... At 12:27 AM 4/10/1999 EDT, you wrote: > There is a lot of good science being discussed on this list in this thread. >Here at Oceanspec we have been conducting a government equipment survey and >reliability test on several different types of equipment. > I have already made the statement to this list that most O2 sensor equipment >should not be trusted. Most notable the gas sensor and testing equipment >available to the dive community from this country. I probably spoke to soon. > I am sure I will be corrected by somebody but our count shows 22 brands of >equipment available to test for O2 content of gas, all can be used in >portable mode all are battery operated. The test gear that was evaluated was >both new and used. The units were tested using Swan or IoneticBM test >comparators calibrated with certified CRG or National Calibration gas in >10/85 21/70, 35/60 and 52/45 gas concentrations. Each test received control >samples from ambient air. >All were tested at 88 F,72F, 60 F ,40 F . All of the equipment was tested >then sent off to be recalibrated (by manufacture recommendations), and then >tested again. > The average negative error (low reading) was 22% of total tested >concentration. That would mean a 52% O2 concentration show 39% on the test >gear. The average positive test reading was 29% above the cal gas values for >that test. The most disturbing was several test that indicated. a 10/85 cal >gas as being a 32% concentration. >The total test package is not yet complete, so I will not talk about each >machine. The errors that we see at the two lower ambient temperatures are so >great that I do not see the utility of even trying to use the equipment. This >problem gets much better if the portable test gear is kept at standard temp. >Gas flow fluctuations against the test head was as big A problem as temp was. >A cheap and safe way out of this problem is to carry a small bottle of cal >gas, probable the 35/60 , give your trusty old "STROKE" machine A sniff and >compare it's read to a known Percentage in the cal gas cylinder. Remember >that not any cal gas will do must be O2 and An inert That should tell you if >there is A problem. >Somebody on this list just recently alluded to the fact that there is no He >test gear that was cheap, try a Draeger tube and a balloon, that will run >about $7.00 per test. Draeger claims an accuracy of + or -05% . That is >better that the Abbot or RocheBM converted gear. > >-- >Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. >Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > -------------------------------------------------- Kevin Connell <kevin@nw*.co*> Northwest Labor Systems http://www.nwls.com Lake Stevens, WA "I suppose you want a user interface with that..." -------------------------------------------------- -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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