It finally happened - my CCR tried to kill me

[Heat Miser]

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...)

You are less lowly than me ... latitude wise. But I'm working hard trying to catch up on the hours thing

 

[broncobowsher]

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...

Summer in AZ, maybe just late spring. Air = hot, water = cold. Get in the drysuit and walk to the water and stand in the water to avoid overheating. So you quickly grab everything before standing in the water and deal with it while standing in cool water. Now you go through the checklist. Open DIL, check ADV, check inflator, opps that is off. That is why we have checklists. Go through the steps in order. The connector is fighting me not wanting to go back on. By the time I have it on I look at the flashing red of a PPO2 of 0.10 and jump off the loop real fast. Couple deep breaths of air. Good thing I was just standing and not physically active. Turning on the O2 was still a few steps away. That is why I moved the O2 way up on the list. Open DIL, check the ADV, turn on O2. Even if it was completely solenoid driven the controller would be trying to keep at least a PPO2 of 0.19 firing a solenoid, just have to have O2 behind it. CMF or leaky valve would also be letting O2 into the loop. Anything to be adding O2 into the loop. Not several steps later finally turning it on. I can check inflators and other stuff with the O2 on, I don't have to wait to open it up.

Keep in mind that this is the pre-jump, you are minutes away from actually starting the dive. So having the O2 on the whole time is a good thing. An extra minute of O2 being open, that better not be an issue with your planning or your planning is way too tight. You are basically doing a dive on the loop, just not in the water yet (except that time I was standing in water only for the cooling). I am NOT referencing the closed (build) check list, That is different and ends with everything off and depressurized. This is the checklist just before you step off the boat. Normally I would still be on land, but to avoid overheating I was standing in water. Passing out at that point would have been bad. Just another shallow water rebreather incident.

 

[stuartv]

Summer in AZ, maybe just late spring. Air = hot, water = cold. Get in the drysuit and walk to the water and stand in the water to avoid overheating. So you quickly grab everything before standing in the water and deal with it while standing in cool water. Now you go through the checklist. Open DIL, check ADV, check inflator, opps that is off. That is why we have checklists. Go through the steps in order. The connector is fighting me not wanting to go back on. By the time I have it on I look at the flashing red of a PPO2 of 0.10 and jump off the loop real fast. Couple deep breaths of air. Good thing I was just standing and not physically active. Turning on the O2 was still a few steps away. That is why I moved the O2 way up on the list. Open DIL, check the ADV, turn on O2. Even if it was completely solenoid driven the controller would be trying to keep at least a PPO2 of 0.19 firing a solenoid, just have to have O2 behind it. CMF or leaky valve would also be letting O2 into the loop. Anything to be adding O2 into the loop. Not several steps later finally turning it on. I can check inflators and other stuff with the O2 on, I don't have to wait to open it up.

Keep in mind that this is the pre-jump, you are minutes away from actually starting the dive. So having the O2 on the whole time is a good thing. An extra minute of O2 being open, that better not be an issue with your planning or your planning is way too tight. You are basically doing a dive on the loop, just not in the water yet (except that time I was standing in water only for the cooling). I am NOT referencing the closed (build) check list, That is different and ends with everything off and depressurized. This is the checklist just before you step off the boat. Normally I would still be on land, but to avoid overheating I was standing in water. Passing out at that point would have been bad. Just another shallow water rebreather incident.

Gotcha. I understand now.

I turn my O2 on before I don the unit, as previously mentioned.

But, I also follow the checklist otherwise, which doesn't start the pre-breathe until after the O2 is turned on...

 

[Dsix36]

I have been out of town for a couple of weeks and thus am a bit late to this party. I see no need to talk about the gas choices as that is a variable depending on dive plan and personal preferences. I will only talk about the rEvo.

1 - Everyone should be taught how to verify that each tank is correctly installed when they do their training. It is not a big deal. You merely install it, WITHOUT ANY ABNORMAL FORCE, and grab the valve a twist to make sure both sides are locked in place. If you did not learn this, your instructor failed to perform properly.

2 - Everyone should be taught how to verify the scrubber cover is installed properly in their training. Since this is p[art of the loop, it is rather critical. Install in a smooth, steady and level to the unit direction (not uneven pressure from the top to bottom or side to side). Make sure the battery box is correctly orientated just prior to putting the retaining nut on. it should still twist a bit very easily and not be bound up. Tighten the retaining nut to the usual position. You did learn where this was the first time you built it RIGHT? If you did not learn this, your instructor failed to perform properly.

3 - Overnight negatives should be avoided. I did this also in the beginning, until Paul himself suggested that it puts unnecessary strain and fatigue on the counterlungs. 3-5 minutes is plenty.

4 - This one is just my personal opinion and like most things I post, may be completely wrong. I find it extremely difficult to believe that a poorly installed tank could cause a leak like this without there being other underlying issues at work. It is my contention that there was either some form of debris on the orings or the scrubber cover (possibly just old orings) OR that the scrubber cover has the early signs of delaminating. Either of these can cause such minor leakage that they can be extremely difficult to find without doing a underwater over pressure test. The misplaced tank could have thus amplified the issue to the point that it was readily noticed.

I base my thoughts on the fact that I have had a tank installed with ratchet straps due to broken mounting tabs and forced so tight to the cover it dented the delrin without any leaks.

 

[davidvan]

Has everyone watched the Divemaster Scuba build/pre-dive checklist video on Youtube?
Reading through this thread, there are a couple of things touched on in there that have come up in the discussion. From memory, the battery cover was discussed.. Also the new version of the rMS probes and how the old ones failed.
If nothing else, it might be a great refresher from rEvo with up to date processes etc.

Divemaster Scuba CCR Build-up and reviews - rEvo III

The guy is an SSI training director, knows the rEvo very well and was even on the Horizon development team, which as you probably know is an SCR adaptation of the rEvo.

 

[stuartv]

Has everyone watched the Divemaster Scuba build/pre-dive checklist video on Youtube?
Reading through this thread, there are a couple of things touched on in there that have come up in the discussion. From memory, the battery cover was discussed.. Also the new version of the rMS probes and how the old ones failed.
If nothing else, it might be a great refresher from rEvo with up to date processes etc.

Divemaster Scuba CCR Build-up and reviews - rEvo III

The guy is an SSI training director, knows the rEvo very well and was even on the Horizon development team, which as you probably know is an SCR adaptation of the rEvo.

IIRC, I have watched that in the not-too-distant past. At one point in the video, the guy says you can de-water the rEvo through the OPV on the counterlung. I took the trouble to contact Adam Wood and ask for clarification on that, as I don't think it is correct. He gave me the email address of the guy who was actually doing the presentation and I emailed my questions to him. I never got a response.

 

[Heat Miser]

II took the trouble to contact Adam Wood and ask for clarification on that, as I don't think it is correct.

Yep I've tried to replicate the inverted dil flush, I'm not certain its effective. Certainly you would get some funny looks from your buddy. I saw Adam sold his rEvo unit on F.B. right after that review. It always struck me as a bit odd, I'd like to know the back story.

 

[stuartv]

Yep I've tried to replicate the inverted dil flush, I'm not certain its effective. Certainly you would get some funny looks from your buddy. I saw Adam sold his rEvo unit on F.B. right after that review. It always struck me as a bit odd, I'd like to know the back story.

I thought about it at the time and I was thinking that if the exhale breathing hose entered the CL and had a relatively short tube sticking down into the CL, you could go to head down trim and overpressurize and it would push water out of the exhale CL. The tube I described would act kind of like the dip tube in a scuba cylinder, keeping any water in the CL from running back down into the breathing loop.

But, to me, the bigger concern is water in the inhale CL (vs the exhale). And for that, there is no OPV in that CL to push the water out through.

Maybe a rEvo redesign will happen some day that swaps the OPV to the other side - to the inhale CL - and this idea could become a reality.

 

[Dusty123]

At least the inhale counter lung can hold a lot of water. Realistically even in pretty flat trim the revo is at a downward angle and getting water into the inhale hose is pretty hard, achievable certainly, but hard.

 

[Wibble]

If you dive flat, any water in the exhale lung runs back down into the exhale loop up to the exhale mushroom. Eventually this bubbles back into the mouthpiece and gives you a 'wet' breathe.

You can do a shakedown manoeuvre to tip liquid back into the exhale lung. Don’t dive flat subsequently or it’ll tip back down.

Some people put another "moisture absorbing cloth" into the exhale lung, but Revo don’t recommend this.

Allegedly the BOV facilitates liquid clearing, but BOVs bring other challenges.