Quote: (Originally Posted by jont)
As always you are very thorough Joe, and accurate I have several questions:
1) Does the new HH allow you to calibrate at lets say 80% o2 (travel issues...like truck were the o2 generators put out between 80 and 95% o2)?
The HH was designed to only calibrate with 100% oxygen.. This being said using the method I describe I can accuractely calibrate at other percentages.. I wouldn't use an 80% source, that tells me something else is wrong.. A PSA system delievers 95.5% o2 when working at optimum, if they push the gas through a bit too fast it will give a lower percentage.. The lowest I would use would be around 90% or so
In theory if the vessel could withstand the pressure I could calibrate with air (assuming the unit calibrates to 1.00/1.013)... but that would mean that the guage pressure would be about 55psi
Quote: (Originally Posted by jont)
2) Do other systems like the insperation (as you know I have 1 working unit and one destroyed unit, the truck incident i told you about) take into consideration that the loop AFTER following the on screen instructions will NOT have a true 100% o2 content?
The inspiration calibrates in a unique manner.. what it does is flush the head with oxygen until it sees no further change on the cells, it then sets the calibration to the pressure setting multiplied by the enetered oxygen percentage.. The cal should be verified and the enetered oxygen percentage could be adjusted +/- 1 percent or so until the correct value is obtained.. that is ambient pressure in bar multiplied by the analyzed oxygen percentage.. The Inspiration displays po2 in bar even though the standard is to express po2 in Atas.. so in reality the displayed po2 (assuming a perfect calibration) is 1.3% lower than the standard.
Quote: (Originally Posted by jont)
3) Units like the prism (just an example) say to flush the loop 3 times, but even after 3 flushes you won't have a true 100% o2 content. How does this effect diving ? and when does this become life threatening?
displayed PO2 is higher than actual
when it becomes dangerous depends on how far the lop was actually off and how close to the edge you push the tables
Quote: (Originally Posted by jont)
4) Is it possible to calibrate such units (that lack true electronics) with less than 100% o2 SAFELY?
Thanks Joe (I am glad someone knows the answers to this stuff)
any unit can be reasonable calibrated as long the calibration value you use is somehow zerod to the scane you want to use, and the entrained loop (or chamber) must be at a pressure that matches what you use in your po2 calibrations.. that is pressure times oxygen percentage..
Thats how my chart works at altitude or another gas percentage.. I know what the result is supposed to be (that is 1.00) so I adjust the pressure so that the gas in use multplied by some pressure equals 1.00ATA,
If the controller sets the PO2 in bar the same offset should work but it will now display 1.013 instead of 1.00