abitton
Contributor
roakey:
Excellent point.
What the....? (analyzer question)
- Thread starter Doc Harry
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Excellent point.
Charlie99
Contributor
- Messages
- 7,966
- Reaction score
- 169
- # of dives
- 500 - 999
Humidity correction chart
My preference is to use ambient air as a sanity check, then a cylinder of air for the actual calibration.
An error of 1% isn't all that big of a deal. A mistake, such as calibrating on a tank that isn't really air has a potential for real problems, particularly on homebrew analyzers that have a wide calibration range such that an EAN32 tank could be calibrated as air.
A check with ambient air prevents a gross error or mistake. A calibration with an air tank using the same flow rate and setup as the measurement will give the best accuracy.
My preference is to use ambient air as a sanity check, then a cylinder of air for the actual calibration.
An error of 1% isn't all that big of a deal. A mistake, such as calibrating on a tank that isn't really air has a potential for real problems, particularly on homebrew analyzers that have a wide calibration range such that an EAN32 tank could be calibrated as air.
A check with ambient air prevents a gross error or mistake. A calibration with an air tank using the same flow rate and setup as the measurement will give the best accuracy.
I have a confession to make at this point. This is the first time I consciously remember hearing about the humidity thing. The confession is that for *years* I've just assumed that the Nitrox compressor where I get my fills just filled a little "hot" in the summer.....
I feel a little stupid ....
R..
I feel a little stupid ....
R..
Calibration can be affected (i) by altitude (ii) by temperature and (iii) by humidity.
With these factors the air at your location may well not be 20.9%.
My analyser comes with a cue card for working out the correct % to calibrate to.
Humidity shouldnt be an issue with tank air as it is (or should be) totally dry so you COULD calibrate off that provided the tank contains air and has never contained nitrox etc.
Better option is to work out the above factors yourself.
Most analysers are also only accurate to about 0.5% so errors of less than this are meaningless.
With these factors the air at your location may well not be 20.9%.
My analyser comes with a cue card for working out the correct % to calibrate to.
Humidity shouldnt be an issue with tank air as it is (or should be) totally dry so you COULD calibrate off that provided the tank contains air and has never contained nitrox etc.
Better option is to work out the above factors yourself.
Most analysers are also only accurate to about 0.5% so errors of less than this are meaningless.
Similar threads
