It finally happened - my CCR tried to kill me
- Thread starter stuartv
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Dusty123
Contributor
75hrs on my present unit, 2018 unit, rms probes work fine.
broncobowsher
Contributor
I build my rEvo either way. Whatever is convenient during the build. Cylinders are ready to go before the scrubber is built up, they go on first. Sometimes I will be building the rEvo not knowing the site yet and will wait to know what cylinders to put on, in which case the scrubber is fully built first.
I ended up making a new set of checklist cards for my rEvo. Once I added the transmitters and running a NERD instead of dreams, it wasn't a very good checklist anymore. So I rewrote them and get a them laser engraved, just like the originals. One thing I moved way up on the pre-jump list was opening the O2. Had an almost incident where I was working the checklist and had the DIL open, working on something that paused the checklist, looked down and saw a stupid PPO2 number. The checklist now goes; open dil, check ADV (for those that still run it hooked up), open O2. Now you can go through the rest of the list and have some sort of O2 being added while doing so.
I ended up making a new set of checklist cards for my rEvo. Once I added the transmitters and running a NERD instead of dreams, it wasn't a very good checklist anymore. So I rewrote them and get a them laser engraved, just like the originals. One thing I moved way up on the pre-jump list was opening the O2. Had an almost incident where I was working the checklist and had the DIL open, working on something that paused the checklist, looked down and saw a stupid PPO2 number. The checklist now goes; open dil, check ADV (for those that still run it hooked up), open O2. Now you can go through the rest of the list and have some sort of O2 being added while doing so.
And this is why, at age 75, I’ll probably not be taking up CCR diving. I may sometime take one into the pool just to try it out, but the complexity makes the diving less fun to me. I’m a vintage diver, and so the double hose regulator of my vintage scuba provides me the ability to get close-up to aquatic life for photography, videos and observation anyway. But this is an interesting thread, as I spent a career in accident prevention, and this discussion is a very relevant and necessary way of passing on information.
SeaRat
OP
Can you elaborate on that? What is/was a stupid ppO2 number?
Why do you want O2 flowing during the whole pre-jump?
I also generally turn on my O2 right at the start of my pre-jump. But, my reason is that I have heard of an oxygen fire from turning the O2 valve open too quickly. I want to turn that on and be sure nothing bad happens before I don the rig...
The complications talked about in this thread are peculiar to the particular brand of rebreather. They all have some intrinsic complication as you need to know your ppO2 and change the sorb but they also simplify gas logistics.
If your (non-CMF) system has previously been on and pressurized, and you turned it off, and you don't have a leak, then there is virtually no repressurization danger. The high pressure spots where adiabatic heating and impact ignition might occur (O2 bottle valve and first stage) are still pressurized behind the IP compartment when you turn the tank back on. There is no (or almost no) net HP gas movement.
With a CMF, the IP compartment gradually bleeds down and the valve opens, emptying the HP section of the first stage. When you reopen the tank valve, there IS a potential surge of 2300 psi oxygen.
Even tho' I don't fly a CMV, I've still installed the AP slow-open oxygen valve on my JJ tank. Watching the clearly slower pressure rise as I crack the valve is very reassuring
The leaky valve / orifice does need some special considerations as it's delivering ~0.5 litres per min. Forgetting to turn it off after the first dive could ruin your second dive. Tend to only do this once though! Once learned, the big issue is controlling the urge to turn it off if there's a delay in jumping in; or if you do, you damn well make sure it's turned back on again before you jump.
So a third checklist: "just before I stand up to jump in check"... arms back to check the O2 & dil cylinders are on (which is a lot easier to check if the valves are fully open), that the suit inflate's connected and working, a tap-down to make sure everything's hanging where it should be, the bailout's turned on, and that your mask, fins and gloves are on your carcass.
Turning on O2 is helped by using slow-opening valves, such as those sold by AP Diving (Inspiration).
Heat Miser
Contributor
Hi @stuartv,
The irony of some of these new posts relative to the original post is not lost on me.
In .... my words:
"You think a flood was caused by not getting one of those little feet from the tank bracket, in the slot of rEvo casing, and it banged the scrubber lid loose enough to leak"
It probably doesn't make a great deal of difference whether the scrubber lid goes on first or the tanks go on second. But it is much easier to see that the tank feet are seated properly without the lid on. It's also easier to hear the solenoid fire. It's easier to inspect the o-rings. It's easier to change the external battery, if its flatish, and doesn't fire as well. it's easier to do the 1/8- 1/4 turn backwards to make certain the external battery cap's not on too hard after you realise you need to replace the battery
I'm a big fan of standards, I don't have a Nerd2 though, TDI standards say lid after tanks fixed.
https://www.tdisdi.com/wp-content/uploads/2016/02/rEvo-checklist-v05-22092015.pdf
Enjoying the discussion, in someways not certain how productive it is ,,, thank you as always, and keen to learn from you ... i.e. that millivolt thing works .... from a lowly MOD 1 certified rEvo owner.... polar opposite side of world.
Regards
The irony of some of these new posts relative to the original post is not lost on me.
In .... my words:
"You think a flood was caused by not getting one of those little feet from the tank bracket, in the slot of rEvo casing, and it banged the scrubber lid loose enough to leak"
It probably doesn't make a great deal of difference whether the scrubber lid goes on first or the tanks go on second. But it is much easier to see that the tank feet are seated properly without the lid on. It's also easier to hear the solenoid fire. It's easier to inspect the o-rings. It's easier to change the external battery, if its flatish, and doesn't fire as well. it's easier to do the 1/8- 1/4 turn backwards to make certain the external battery cap's not on too hard after you realise you need to replace the battery
I'm a big fan of standards, I don't have a Nerd2 though, TDI standards say lid after tanks fixed.
https://www.tdisdi.com/wp-content/uploads/2016/02/rEvo-checklist-v05-22092015.pdf
Enjoying the discussion, in someways not certain how productive it is ,,, thank you as always, and keen to learn from you ... i.e. that millivolt thing works .... from a lowly MOD 1 certified rEvo owner.... polar opposite side of world.
Regards
OP
I have learned a LOT from this discussion!
And, I am also just a lowly MOD1 rEvo owner... (my MOD1 did include Advanced Recreational Trimix and deco...)
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