Calibrating the night before?

**Dsix36** · 30th December 2007, 15:41

Quote: (Originally Posted by divingabe)

Yes I do mean the reading on the handsets. After calibration it will read 20.9 on air. The next morning it should read the same as when you calibrated and to be .1 off either way would not warrantee recalibrating unless you feel compelled to do so. My view is if it does show greater than .1 off I would then recalibrate.

IMHO .1 is way too much variance for just setting overnite with a fresh calibration. I am thinking that the calibration was done improperly or you have some sensor drift. .01 is much more in the ballpark.

.1 difference is only acceptable (to me of course, you have to decide for yourself) after about 3-4 hours of diving. I would consider it drift from moisture in this instance (happens to me every time at about 3 hours). This is usually done in four dives of 1 hour each during the course of a day.

Mark Chase · 2nd January 2008, 12:33

Is a meg some how different to my unit ?

I calibrate my unit (Hammer Head Inspo, VR3, Shearwater or KISS) and leave it calibrated till it reads wrong.

That could take weeks, even months.

On assembly i check the hand sets in air and expect 0.19-0.25 and then I flush the unit three times with 02 and i expect to see 0.97-100%

If I do, I go diving. If i find then at the limits or just outside my personal tolerance for error, I recalibrate the unit.

If I find one cell is significantly out or all three cells are showing significantly high or low I will first check the unit for an issue rather than recalibrate.

Ill re-check the gas against a known source (Usually my Js of premix or 02) and then Ill look for dodgy connections on the cells or Fischer cables/connections.
Ill swap the cells about to see if the error followed the cell and only when totally satisfied its not one of these issues will I recalibrate.

I never liked the Inspo thing about "calibrate first and ask questions later". It seemed to me the unit is telling you there is a problem but we just recalibrate the cells to work around the issue.

ATB

Mark Chase

G4SSG · 2nd January 2008, 13:23

Quote: (Originally Posted by Mark Chase)

Is a meg some how different to my unit ?

I calibrate my unit (Hammer Head Inspo, VR3, Shearwater or KISS) and leave it calibrated till it reads wrong.

That could take weeks, even months.

On assembly i check the hand sets in air and expect 0.19-0.25 and then I flush the unit three times with 02 and i expect to see 0.97-100%

If I do, I go diving. If i find then at the limits or just outside my personal tolerance for error, I recalibrate the unit.

If I find one cell is significantly out or all three cells are showing significantly high or low I will first check the unit for an issue rather than recalibrate.

Ill re-check the gas against a known source (Usually my Js of premix or 02) and then Ill look for dodgy connections on the cells or Fischer cables/connections.
Ill swap the cells about to see if the error followed the cell and only when totally satisfied its not one of these issues will I recalibrate.

I never liked the Inspo thing about "calibrate first and ask questions later". It seemed to me the unit is telling you there is a problem but we just recalibrate the cells to work around the issue.

ATB

Mark Chase

hi
I would say not different at all
except the meg uses 2 point calibration
air then o2
all monitors or controllers need a reference point ,how could it ever be any different..
cal on air or o2 ...just that o2 narrows the error down a little
as i'm sure you know .....martyn

**wedivebc** · 2nd January 2008, 22:40

I haven't calibrated my meg in several weeks (12-15 dives). I usually calibrate when it's out more than 0.01. My latest batch of sensors have been rock-solid.

30th December 2007, 15:41	#11 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 879	Re: Calibrating the night before? Quote: (Originally Posted by divingabe) Yes I do mean the reading on the handsets. After calibration it will read 20.9 on air. The next morning it should read the same as when you calibrated and to be .1 off either way would not warrantee recalibrating unless you feel compelled to do so. My view is if it does show greater than .1 off I would then recalibrate. IMHO .1 is way too much variance for just setting overnite with a fresh calibration. I am thinking that the calibration was done improperly or you have some sensor drift. .01 is much more in the ballpark. .1 difference is only acceptable (to me of course, you have to decide for yourself) after about 3-4 hours of diving. I would consider it drift from moisture in this instance (happens to me every time at about 3 hours). This is usually done in four dives of 1 hour each during the course of a day. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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2nd January 2008, 12:33	#12 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,461	Re: Calibrating the night before? Is a meg some how different to my unit ? I calibrate my unit (Hammer Head Inspo, VR3, Shearwater or KISS) and leave it calibrated till it reads wrong. That could take weeks, even months. On assembly i check the hand sets in air and expect 0.19-0.25 and then I flush the unit three times with 02 and i expect to see 0.97-100% If I do, I go diving. If i find then at the limits or just outside my personal tolerance for error, I recalibrate the unit. If I find one cell is significantly out or all three cells are showing significantly high or low I will first check the unit for an issue rather than recalibrate. Ill re-check the gas against a known source (Usually my Js of premix or 02) and then Ill look for dodgy connections on the cells or Fischer cables/connections. Ill swap the cells about to see if the error followed the cell and only when totally satisfied its not one of these issues will I recalibrate. I never liked the Inspo thing about "calibrate first and ask questions later". It seemed to me the unit is telling you there is a problem but we just recalibrate the cells to work around the issue. ATB Mark Chase __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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2nd January 2008, 13:23	#13 (permalink)
G4SSG New Member Current Rebreather/s: Ouroboros Home Build Other Rebreather/s: Inspiration Classic Megalodon Home Build Join Date: Dec 2005 Location: UK...Midlands Posts: 56	Re: Calibrating the night before? Quote: (Originally Posted by Mark Chase) Is a meg some how different to my unit ? I calibrate my unit (Hammer Head Inspo, VR3, Shearwater or KISS) and leave it calibrated till it reads wrong. That could take weeks, even months. On assembly i check the hand sets in air and expect 0.19-0.25 and then I flush the unit three times with 02 and i expect to see 0.97-100% If I do, I go diving. If i find then at the limits or just outside my personal tolerance for error, I recalibrate the unit. If I find one cell is significantly out or all three cells are showing significantly high or low I will first check the unit for an issue rather than recalibrate. Ill re-check the gas against a known source (Usually my Js of premix or 02) and then Ill look for dodgy connections on the cells or Fischer cables/connections. Ill swap the cells about to see if the error followed the cell and only when totally satisfied its not one of these issues will I recalibrate. I never liked the Inspo thing about "calibrate first and ask questions later". It seemed to me the unit is telling you there is a problem but we just recalibrate the cells to work around the issue. ATB Mark Chase hi I would say not different at all except the meg uses 2 point calibration air then o2 all monitors or controllers need a reference point ,how could it ever be any different.. cal on air or o2 ...just that o2 narrows the error down a little as i'm sure you know .....martyn
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2nd January 2008, 22:40	#14 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,355	Re: Calibrating the night before? I haven't calibrated my meg in several weeks (12-15 dives). I usually calibrate when it's out more than 0.01. My latest batch of sensors have been rock-solid. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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