Analox analyzer

[stuartv]

That's my point. The Analox doesn't have any way to display anything except the current FO2. No mV reading available. And only adjustment for calibration. So, I don't see how you can do a dual calibration. And, personally, I may check the calibration against a high and low value. But, I would calibrate against a known gas that is closer to the FO2 I expect to be measuring. I.e. if I'm measuring Nitrox bottom gas, I would calibrate against air. If I'm measuring a deco bottle of 80% (requested) O2, I would calibrate against 100% O2, if available.

 

[tarponchik]

cal gas should ideally be O2 since that is going to be the most accurate gas that you'll have access to provided it comes from lOx if possible or supplied tanks from the gas suppliers. These have been vacuumed and filled, so you know they're going to be as accurate as possible. It also gives you an ideal of any voltage limits from the cell itself since you can do a two point calibration

O2 will kill the sensor too soon. Ideally, there should be 2 calibration standards, air and N2 (or any other gas with zero O2). But this will get a bit complicated.

 

[GlennL]

Well I appreciate the replies. I understand rounding down for safety and not pushing the mod. I was more or less interested because I was getting about a .3 difference by just doing an ambient cal. I talked to analox about it today. They told me to send it in to get checked out and if they find a problem they will replace the sensor for free since it is less than a year old.

 

[MadUKDiver]

The Analox humidity compensation chart is in their manual on the last page (link)

 

[RainPilot]

0.3 is well within the error margin of the instrument on a good day anyway, I wouldn't lose sleep over it.

 

[GlennL]

The Analox humidity compensation chart is in their manual on the last page (link)

Which is why my original question was about a humidity gauge I could toss in my bag

 

[GlennL]

0.3 is well within the error margin of the instrument on a good day anyway, I wouldn't lose sleep over it.

I'm not loosing sleep. I just want as accurate info as possible, especially after spending a few hundred on the device

 

[RainPilot]

I'm not loosing sleep. I just want as accurate info as possible, especially after spending a few hundred on the device

Fair enough. You could probably use a weather app on your phone for local humidity readings, I suspect 0.3 is as good as it's going to get within the limits of the device anyway.

 

[lermontov]

I'm not loosing sleep. I just want as accurate info as possible, especially after spending a few hundred on the device

you've obviously done a nitrox course so as long as you understand the implications of the readings +/- and know how to compensate then your good to go. As far as accuracy for the analyser Im not sure what the acceptable range is but you can get that sort of discrepancy just by opening the valve too much. I would be more interested in consistancy of reading

 

[stuartv]

The Temp/Humidity Compensation chart has a range of 20.2 to 20.8 from temps from 70 to 80 degrees F (21 - 27C), and humidity from 10 to 100%.

The vast majority of my calibrations are in that temp/humidity range, so if I don't have a thermometer and hygrometer I usually just give it a best guess and calibrate to ambient air with a setting of 20.6 or thereabouts (+/- a little bit depending on how hot/cold and humid/dry it feels). I figure the resulting measurement that I get is plenty close enough.

As lermontov pointed out, unless you have a 2 lpm (??) flow restrictor to precisely regulate the flow into the analyzer, you can't treat the result as super precise anyway.