calibrating on multiple days diving

[rjack321]

Could you please clarify linear deviation? Are you talking about:
1)points not on the expected "Slope" line with each end at the expected point

OR

2)one end of the slope starts on an expected point and it trends off the entire run?
View attachment 674480

A 2 point calibration would be moving your origin point up/down the Y axis a tiny bit. The risk is if you get o2 on the cells and then tell them that point (way too high) on the Y axis is "air". Then your whole slope is completely wacked. Really bad news.

Very few units have a 2 point calibration because the juice isnt worth the squeeze for that normally tiny Y axis change (which is more or less just a change in atmospheric pressure for your calibration day/weather/altitude).

 

[wedivebc]

Since very few divers, fewer instructors, and even fewer instructor trainers acknowledge that linear deviation is a thing, they usually don't calculate predicted mV output for calibration. .

Once again you make very far reaching statements based on a limited data set. I teach linear deviation to all my students and instructor candidates. All the instructors I know teach it as a fundemental aspect of cell characteristics.

 

[wedivebc]

Could you please clarify linear deviation? Are you talking about:
1)points not on the expected "Slope" line with each end at the expected point

OR

2)one end of the slope starts on an expected point and it trends off the entire run?
View attachment 674480

Your #2 graph is closer to real world behaviour. The early Megs attempted to compensate for that by using a 2 point calibration system however it was prone to user error sometimes resulting in inaccurate calibrations.

 

[tbone1004]

Once again you make very far reaching statements based on a limited data set. I teach linear deviation to all my students and instructor candidates. All the instructors I know teach it as a fundemental aspect of cell characteristics.

come to cave country, it’s scary… or the rest of the east coast for that matter

 

[wedivebc]

come to cave country, it’s scary… or the rest of the east coast for that matter

Been there and I agree, although cave country does not represent a majority of RB instructors, or even divers. As a dive professional for over 20 years and RB instructor for 17 years, I might know a couple of instructors and RB divers myself and my experiences don't reflect your comments above.

 

[kensuf]

About a week ago I caught a cell that went non-linear (and way outside of spec) that was only 3 months old through validation/pre-dive calibration every morning. It only takes a minute to do.