Think I'll stick to Martin Parker's advice, I'm sure it won't do me any harm ***55357;***56835;
Double Fatality in June 2014 (UK) - Inquest and Media Reports
- Thread starter GLOC
- Start date
Think I'll stick to Martin Parker's advice, I'm sure it won't do me any harm ***55357;***56835;
Mark Chase
ATB=AlwaysTalkingBollocks
3-4 dives or 8ish hours in I start to beleive it will actualy work for a while
Prety much all my new cell dive failures have happened in that time scale but I have had cells that failed within 12 months but after 8 hours however they were not Bud cells or a Narked @ 90 cells
I dont like APD mainly because I dont like Martin Parker's buisness model (think early design issues with the Classic, early release issues with the Vision, the whole APD cell debarcle and the attempt to restrict the Sofnalime market for his own benifit) and I strongly disagree with some of his advice on isues like cells and scrubber filling, but I always baught their bud cells as they were very good
ATB
Mark
Mark Chase
ATB=AlwaysTalkingBollocks
I am not so sure.
I beleive calibrating over a faulty cell or wireing issue has been the starting point for several serious diveing issues.
I really have no idea about calibrating an AP unit but help me out here.
mV in air are within specs
mV in 100% are within specs
mV in 100% are within 10% of mathematical prediction (which I actually think is too broad but I digress)
How is establishing this as a "new" line in the calibration going to precipitate a problem?
Mark Chase
ATB=AlwaysTalkingBollocks
OK lets say the cell output is unstable as a result of internal fault or external wireing issue. The calibration is out so you recalibrate the cell and the cell is within calibration tolerance so it recalibrates. The the intermitent fault is reactivated during the dive or the environmental conditions exasabate the origional failure and suddenly your calibrating over the first sign of a problem has left you with cell readings that are wildly out
I have had this several times on the Inspiration Classic (which I dont beleive did two point calibration? Does the vision do air and 02 calibration?)
I surfered many many cell issues on the Inspo classic right up to the point I discovered Biox to clean the cell contacts and wires with.
I also suffered an intimitent cell failure on my JJ which turned out to be the coax conection had snaped and was only being held in contact by the rubber cell cap
Simple truth: Cells hardly ever need calibrating. They do new till they stabalize and they do when they get old. The bit in the middle? they just work
If a cell is out to the point of requiring a re calibrate in my experiance its either faulty or on its way out.
ATB
Mark
GLOC
real name: Gareth Lock!
Mark, what about air pressure changes? I am not talking about day to day, although those can be large but the weather would be so crap you wouldn't be diving, but over a longer period of time? Does that make enough of a difference?
What air pressure changes do you need to be sure that recalibration isn't required? If the HUD is rounding to the closest 0.x value, surely there can be some issues here between mismatched information from the handset and HUD?
You need to be careful with statements like "Simple truth" because unless you have large amount of data across different cells, units, users and environments, it is your opinion given your experience and not fact. However, if you have that data, that would be great to share.
Finally, how do you define "the bit in the middle"? How do you know when the 'new' has stopped being 'new' and is now on its way out?
Regards
What air pressure changes do you need to be sure that recalibration isn't required? If the HUD is rounding to the closest 0.x value, surely there can be some issues here between mismatched information from the handset and HUD?
You need to be careful with statements like "Simple truth" because unless you have large amount of data across different cells, units, users and environments, it is your opinion given your experience and not fact. However, if you have that data, that would be great to share.
Finally, how do you define "the bit in the middle"? How do you know when the 'new' has stopped being 'new' and is now on its way out?
Regards
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matt
Well-Known Member
I think the simple truth is that the vast majority of Inspiration divers are calibrating each day or dive.
I've never cleaned my cells connections in 13 years.
I agree that it takes only a short time to prove a cell working and I've found that if they are to fail the will do so in the first 4 hours - then they tend to be ultra reliable; unless they are from APD.
Matt.
Mark Chase
ATB=AlwaysTalkingBollocks
We digress
Ill answer all this but lets please not lose focus on the fact cell issues wernt the cause of death it was failing to notice and or properly act upon cell issues that caused the death.
The BP issue has proved insignificant for me.
I have found my HUD on the JJ tracks the handset well but I agree you can get anoying mis match flashes on the hud and probably calibrate the HUD (which is NOT controling the PP02) a lot more than i do the hand set
Firsty two or three dives with new cells I find they move on calibration generaly reading slightly high. Then they stabalize and remain constant prety much till I replace the cells in May but in my experiance once a cell startes to drop off calibration its usualy dead or current limited in the next 10 hours underwater or 3-5 dives.
The more active I am the more likley the cells will start to drop off before the switch which i have always asumed was because of the shear lenght of time I spend on deco in a year on high PP02 or pure 02.
If i do 150 hours in a year its likley 100+ of those were on deco and 50 ish on on PP02s of 1.5+
A cell is like a battery and the more you use it on full power the quicker it will run out.
I have killed cells on my KISS by accidentely leaving a pure 02 loop closed and a week of sitting in pure 02 has caused a cell to fail
I have used about 4 diferent cells (possably 5) in the last 10 years in five diferent units.
Every time I purchased a unit id fit new cells so I had a start point so I have probably used more than 10 sets of cells
The inspo Classic was absolute murder for cell errors but I am sure that was more down to wireing than anything else. The Hammer Head was extreemly fussy on cells and that rejected the cells that the Classic accepted. The KISS never had an issue. The rEvo would suffer from moisture on the cells and I found it harder to get 1.6 on the rEvo than on any other unit I have dived. The JJ has been faultless except for the broken coax
Bud cells were very solid in my KISS rEvo & Hammer Head. the classic issues didnt realy allow me to coment on the cell performance.
AI cells were all over the place and I binned them within two months of purchase
APD cells were a joke
Narked @ 90 Cells have been rock solid
The solid performance of the JJ and N@90 cells is another reasion I am going back to MCCR as I was getting into "why bother with the checks" mode so being directly incontrol of 02 addition gives me another layer of safety and promotes variables on the cells whic keep you seing cell reaction time and increases the number of times you check yor cells significnatly.
I know a statastition will laugh at my paultry database but but I cant apolagise for putting forward the data I have amassed in 10 years and a reasnobly long time underwater at the higher end of recreational OW run times which i find tends to highlight all sorts of issues.
I add to my personal expeiance me being witness to many many other incidents and discussion on the same with other divers in my group or just on the boat
I have found the new cell errors to be common, APD cell issues to be common, AI cell issues to be common, Wireing issues to be common, Corroson issues to be common
Its water off a ducks back to me but belittling input from divers actualy out there diving the damed things is not consructive.
Manufacturors put out all sorts of blerb and how too's on many things in life that when we actualy use them turns out to be crap
I never understand why divers think CCR manufacturors are any diferent in this reguard.
GLOC
real name: Gareth Lock!
Mark, I am not belittling you. I am stating a position. You are under the influence of a bias that is local to you. What you are saying may be correct for the wider population, but you cannot say it is the simple truth because you do not know everything that is going on.
I agree that this is digression from the OP. Two people died, one of which because there did not appear to be a positive effort to resolve the information in front of them at the time and end the dive (or not even start it if it happened that early on). The discussion then went on to say that many decisions appear to be flawed after the effect, but you cannot be sure what the decision making process was unless you understand the context and the attitude of the people involved. This is why I am very keen to get people to talk honestly about non-fatals and what led to the decisions being made, given the pressures that were out there at the time. Fatals are almost impossible to get a clear indication as to the background because the deceased is really the only one knows
There are few issues with CCR equipment that are 'technically' undetectable either through feedback of the pO2 in the system or other factors. Whether the diver 'detects' them is a different matter as they may be focussed on something. Selective Attention plays a big part in missing the information that is out there.
Regards
I agree that this is digression from the OP. Two people died, one of which because there did not appear to be a positive effort to resolve the information in front of them at the time and end the dive (or not even start it if it happened that early on). The discussion then went on to say that many decisions appear to be flawed after the effect, but you cannot be sure what the decision making process was unless you understand the context and the attitude of the people involved. This is why I am very keen to get people to talk honestly about non-fatals and what led to the decisions being made, given the pressures that were out there at the time. Fatals are almost impossible to get a clear indication as to the background because the deceased is really the only one knows
There are few issues with CCR equipment that are 'technically' undetectable either through feedback of the pO2 in the system or other factors. Whether the diver 'detects' them is a different matter as they may be focussed on something. Selective Attention plays a big part in missing the information that is out there.
Regards
I'm not sure any of this matters. Calibration is just establishing a line either from 0 mV or from ~9 mV (depending on cell manufacturer but most are around this value in air) to a 100% O2 mV output. If the cell outputs are in spec you establish a slightly revised line. Done. If there's dodgy wiring you are not hiding that fact, its just as dodgy as before calibration and you aren't hiding anything.
The first diver "should" have known the cells in his Meg were ancient, years beyond recommended replacement interval. After he missed that, if he calibrated, its pretty doubtful the 4yo or 3yo cells would have output within specs. The 18month old cell, probably. If he had bothered to calibrate and record the mV outputs along with expected mV outputs as taught, he should have detected some sort of cell health issue long before splashing. Maybe he did and splashed anyway, we will never know. But dissuading people from calibrating because he could (maybe) figure out that his cells were long past their replacement date at depth is not learning much from this fatality. The incident pit (in theory) should have stopped in his garage days before the fatal dive.
Mark, I am not belittling you. I am stating a position. You are under the influence of a bias that is local to you. What you are saying may be correct for the wider population, but you cannot say it is the simple truth because you do not know everything that is going on.
I agree that this is digression from the OP. Two people died, one of which because there did not appear to be a positive effort to resolve the information in front of them at the time and end the dive (or not even start it if it happened that early on). The discussion then went on to say that many decisions appear to be flawed after the effect, but you cannot be sure what the decision making process was unless you understand the context and the attitude of the people involved. This is why I am very keen to get people to talk honestly about non-fatals and what led to the decisions being made, given the pressures that were out there at the time. Fatals are almost impossible to get a clear indication as to the background because the deceased is really the only one knows
There are few issues with CCR equipment that are 'technically' undetectable either through feedback of the pO2 in the system or other factors. Whether the diver 'detects' them is a different matter as they may be focussed on something. Selective Attention plays a big part in missing the information that is out there.
Regards
What issues are 'technically undetectable'?
Mike Ferguson
WTF is that?
as has been pointed out previously the thread has diverged.
the discussion on calibrating or not calibrating cells every dive or constantly recalibrating covering up failing cells has nothing whatsoever to do with the fatality caused by a) using ancient current limited cells b) not doing a dil flush to confirm which were right and which were wrong c) not bailing out if you couldn't do a dil flush.
nobody has advocated jumping in with 4 yr old cells. Mark has quite rightly pointed out that blindly assuming a cell is good because it is new is a foolish thing to do as cell failure follows a bathtub curve and early life cell failure is more likely in a quality cell than a failure after a few months whilst bumping along the bottom of the bathtub. However cells can fail anytime so a little paranoia and always assumimg they will fail and checking them during the dive will keep you alive.
if you don't agree with the argument that constant recalibration, under effectively constant environmental conditions, potentially masks cell degradation then the very best thing you can do is to follow the manufacturers recommendtions to the letter.
PS I don't buy that the first diver didn't know how old his cells were. however I do buy the argument that they were fine every other time he used them so he became complacent. I also buy into the argument that ultimately it wasn't the ancient cells that killed the poor chap, it was the lack of cell verification when the cell values diverged during the dive.
as previously requested by others can one of the mods attempt to split this thread?
Mark Chase
ATB=AlwaysTalkingBollocks
Mark, I am not belittling you. I am stating a position. You are under the influence of a bias that is local to you. What you are saying may be correct for the wider population, but you cannot say it is the simple truth because you do not know everything that is going on.
I agree that this is digression from the OP. Two people died, one of which because there did not appear to be a positive effort to resolve the information in front of them at the time and end the dive (or not even start it if it happened that early on). The discussion then went on to say that many decisions appear to be flawed after the effect, but you cannot be sure what the decision making process was unless you understand the context and the attitude of the people involved. This is why I am very keen to get people to talk honestly about non-fatals and what led to the decisions being made, given the pressures that were out there at the time. Fatals are almost impossible to get a clear indication as to the background because the deceased is really the only one knows
There are few issues with CCR equipment that are 'technically' undetectable either through feedback of the pO2 in the system or other factors. Whether the diver 'detects' them is a different matter as they may be focussed on something. Selective Attention plays a big part in missing the information that is out there.
Regards
As vain as i may appear to be, I didnt mean just me, I ment anyone chiming in with experiance
As I said water off a ducks for me I have thick skin and I dont back down easily from what I beleive strongly in. But as you can I am sure would confirm, I am not the sort not to change my opinion in light of solid information.
Selective attention?
In a car thats driving without due care and atention which can result in death or injury to a third party.
CCR is not much diferent
They tryed to automate stuff out for cars and with a multi million pound budget for R&D we got this
https://www.youtube.com/watch?v=aNi17YLnZpg
and this
https://www.youtube.com/watch?v=BYY7OfQ4-5A