Molex Part # for rEvo O2 sensor

[stuartv]

they're necessary evils if you subscribe to required dual monitor solutions. On digital CCR's it's one thing where data can be sent out from the O2 board, but on analog CCR's I would much rather use a single monitor than try to split them.

They're a necessary evil IF you are trying to use 2 monitors with only 3 sensors....

 

[tbone1004]

They're a necessary evil IF you are trying to use 2 monitors with only 3 sensors....

only on analog CCR's, the digital ones don't need them

 

[stuartv]

only on analog CCR's, the digital ones don't need them

Yet another reason I like my hybrid. Digital ppO2 to the controller. But, if the board that is collecting O2 sensor readings dies, I still have an independent analog monitor (my NERD2) getting live ppO2 readings and giving me a good ascent plan. As it did last week after I got the 3 sensors on my digital O2 board totally wet with caustic.

If your digital O2 sensor board dies, what do you do then? Fall back to a computer running in Constant PO2 mode that is "normally" very close to your (now-dead) controller for your ascent plan?

 

[tbone1004]

Yet another reason I like my hybrid. Digital ppO2 to the controller. But, if the board that is collecting O2 sensor readings dies, I still have an independent analog monitor (my NERD2) getting live ppO2 readings and giving me a good ascent plan. As it did last week after I got the 3 sensors on my digital O2 board totally wet with caustic.

If your digital O2 sensor board dies, what do you do then? Fall back to a computer running in Constant PO2 mode that is "normally" very close to your (now-dead) controller for your ascent plan?

yes, fall back to offboard computer to finish ascent either in SCR mode or bailed out. They're most definitely close enough. On a 3-4hr dive with an hour or more of deco I am typically within 2-3 minutes of the onboard monitor.

 

[stuartv]

Final question do you know why a dream O2 sensor splitter and a shearwater O2 sensor splitter are different. They look the same?

I think the Dream splitter only has an isolator in one leg. I think the isolator leg is supposed to be connected to the Shearwater and the non-isolator leg connected to the Dream.

Some people say the isolator is a resistor. I had asked a factory tech once if the isolator was not a diode and he said yes, it is. But, I'm not sure that he KNEW that, or was just speculating.

The splitter that rEvo sells for splitting to 2 Shearwaters has isolators in both legs.

Yep I had thought about that, its more of an interesting project to do. I'm only Mod 1 so I have honestly only dived Tx 11 times, and for those 3 fills I've used the diveshop/instructor's O2/Helium analyser. The original publisher is investigating ways to make a 3d printed trimix analyzer, so if I can make 2-3 of these Nitrox analysers, I'll be good to go if he ever gets that one off the ground. I like the idea of recycling the old rEvo cells. I throw out 2 every year.

Lots of things to buy yet .... booster, compressor, DPV .... trimix analyzer ..... backup perdix or teric ,,,, boat

You only throw out 2 sensors per year?! How long are you running your sensors??

I don't run any sensor more than 12 months, so I'm throwing out 5 per year. I have a reminder set on my computer calendar. It recurs every 10 weeks, reminding me to buy one sensor. When the new sensor comes in, I throw out my oldest one, plug in the spare that I got 10 weeks prior, and have a new spare in my box.

Actually, I generally keep the one I took out most recently, also, so I generally have 2 extra sensors on hand. If the sensor in my Divesoft trimix analyzer dies, I'll put in the used one I last took out of my rEvo. Next time the sensor in my Analox Nitrox analyzer dies, I'm going to see if I can get an adapter to let me use an old rEvo sensor in that, too.

 

[stuartv]

yes, fall back to offboard computer to finish ascent either in SCR mode or bailed out. They're most definitely close enough. On a 3-4hr dive with an hour or more of deco I am typically within 2-3 minutes of the onboard monitor.

Staying on the loop (in CC mode) and using a backup computer that is still getting live ppO2 readings sure does sound a lot nicer than that. No redundancy for the single board that relays O2 sensor readings to your computer(s) is pretty surprising in this context (of people wanting redundancy for everything possible/practical).

 

[tbone1004]

Staying on the loop (in CC mode) and using a backup computer that is still getting live ppO2 readings sure does sound a lot nicer than that. No redundancy for the single board that relays O2 sensor readings to your computer(s) is pretty surprising in this context (of people wanting redundancy for everything possible/practical).

depends on how much you need/want to stay on the loop vs the hassle of cell splitters or dealing with 5 cells. I think the 5 cell concept is retarded and using cell splitters really doesn't add much of anything to me, which is why my KissKat has 3 cells, one monitor, and if it goes sideways I'll bailout.

 

[stuartv]

depends on how much you need/want to stay on the loop vs the hassle of cell splitters or dealing with 5 cells. I think the 5 cell concept is retarded and using cell splitters really doesn't add much of anything to me, which is why my KissKat has 3 cells, one monitor, and if it goes sideways I'll bailout.

Disclaimer, for anyone else reading this, I want to be clear that I am a MOD1 CCR diver. I.e. I am very inexperienced and what I'm saying here is for the purpose of getting critiqued and learning from more experienced people. I also have NO cave training at all.

@tbone1004 It seems to me that what you said there is very much colored by your personal technical, CCR diving, which is primarily cave diving. (I think) For your diving, it will be normal to stage all the BO you could possibly need in the cave, so that if you do feel a need to bail, it's not that big a deal.

A lot of what I'm thinking/saying is colored by my interactions with one of my main dive buddies who does not dive caves at all, but does regularly dive very deep wrecks. I think his deepest so far is the Transylvania, off Malin Head, at 420fsw.

From my understanding, on a dive like that your thought of just bailing if your O2 sensor board went out doesn't sound so great. On those days, no individual can really carry ALL the BO they would need for themselves, so they rely on being able to get BO from teammates and then having O2 waiting on them on the deco trapeze at 20fsw/6m. And if they get blown off the wreck and can't get back to the shot to ascend to the trapeze, and they're on BO, then they are royally screwed.

On a dive like that, having a redundant source of ppO2 info being fed live into a backup computer seems like a huge advantage.

Additionally, that same buddy of mine (who dives a 3 sensor unit) used to say the same as you. "5 sensors is just silly. I'm diving with all these guys who do and have done major deep wreck dives all over the world and they all use 3 sensors. 5 is just silly."

Then he want to Bikini Atoll and right after he got there, a connector for one of his sensors turned out to be so corroded that it would no longer work. It was a connector in the head of his unit, not a sensor connector. They could fix it and he didn't have a spare head or that part of a head. So, he had to choose between diving his CCR with 2 sensors or diving OC. Since that trip, he has never again made a disparaging comment about having 5 sensors.

 

[tbone1004]

@stuartv that's what bailout rebreathers are for. Also once you hit the O2 stops, you don't need any ppO2 readouts. O2 stops can and arguably should be done on loop volume alone, but once you hit O2, you are on an O2 breather, and O2 breathers don't usually have ppO2 displays. Getting to 20ft may suck, but

20mins at 420ft requires an 80 of 10/70, 80 of 21/35, 80 of 35/25, 80 of 50%, and 1x 80 of 100%. That is not that difficult to carry, especially if you are diving a boat rig with the bottom mix in 50's. 4x 80's are not bad with a leash, but if that's too much, then BoB. You may choose to bring a 40 or second 80 of 50% as a contingency, but 4-5 bottles is not terribly difficult.

I would do that trip on 2 sensors without hesitation. Run the unit manually in parachute mode and call it a day. 5 sensors is an equipment solution to a skills problem. The skill in this case being inadequate maintenance of the unit.

 

[rjack321]

A lot of what I'm thinking/saying is colored by my interactions with one of my main dive buddies who does not dive caves at all, but does regularly dive very deep wrecks. I think his deepest so far is the Transylvania, off Malin Head, at 420fsw.

From my understanding, on a dive like that your thought of just bailing if your O2 sensor board went out doesn't sound so great. On those days, no individual can really carry ALL the BO they would need for themselves, so they rely on being able to get BO from teammates and then having O2 waiting on them on the deco trapeze at 20fsw/6m. And if they get blown off the wreck and can't get back to the shot to ascend to the trapeze, and they're on BO, then they are royally screwed.

This is just lazy BS.
Carrying all the gas you need for a 420ft dive does make you look like a Christmas tree but its totally do able. Also bringing safety divers so you are not tethered to the mooring is also do-able. Relying on team BO went the way of the dodo years ago because it does not work (reliably).

Then he want to Bikini Atoll and right after he got there, a connector for one of his sensors turned out to be so corroded that it would no longer work. It was a connector in the head of his unit, not a sensor connector. They could (not right?) fix it and he didn't have a spare head or that part of a head. So, he had to choose between diving his CCR with 2 sensors or diving OC. Since that trip, he has never again made a disparaging comment about having 5 sensors.

There are units which are more and less sensitive to flooding, loop humidity, basically water in one form or another inside. Bringing 5 sensors so you can afford to lose some and dive with a broken unit is balony. This issue is solved by buying a unit which is easier to field repair or better yet designed so you don't have internal corrosion in the first place. Alternatively, in a pinch, get it inspected and serviced before a trip of a lifetime half a world away.