IDA-71 Screw-up

Mossyback

Hi Folks,

After my Bahamas trip I decided there were things about my "71" that needed modifying. I changed my add system for O2 and added a manual add for the diluent side. I re-routed the internal plumbing and moved the diluent to the outside. I originally tried to stuff it all inside the case but it left me with regulators hanging out the bottom making it difficult to stand it up on a dive bench on a boat. See the photos below for my "new" arrangement.

Now for the "screw up". I obviously didn't think my options out very well. I was using my 30 cu. ft. bailout bottle for too many things - BC, Drysuit, Diluent and Bailout. The Diluent bottle plugs into my IDA-71 with a quick disconnect (see photo).

We had been diving on a wreck at 105' and were starting up the line at the end of the dive. At 45' the diluent feed line blew off at the top of the "71" (see photo, the hose without the clamp). I heard the rush of air and initially thought that my exhaust hose had come loose. By the time I went for the quick disconnect, my diluent bottle was empty. My buddy (wife) was kind enough to let me use her octo for the 4 minutes of deco time we had left and we finished the dive with no further problems.

Lessons learned:

1. I'm going to use the 1.7 L Faber bottle that I had originally tried to use inside the unit for Drysuit/BC. I need some way of clamping it onto the unit.
2. Dave Sutton is providing me with a BOV. Although that wouldn't have helped in this situation, it will help with CO2 problems if they should occur in the future.
3. My Bailout/Diluent bottle will feed my "71" and the BOV. If a problem ever occurs again, an immediate disconnect from the unit and a switch to OC should be accomplished quickly.

Any other suggestions for improvements are welcomed.

Hank (Long in the tooth and aiming for triple digits)

Attached Images

	Internal Plumbing.jpg (48.9 KB, 251 views)
	O2 Add.jpg (42.6 KB, 253 views)
	Diluent Add.jpg (48.3 KB, 252 views)
	Diluent Plumbing.jpg (43.3 KB, 248 views)

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undrh2o

Hank, glad you made it back - how did it blow off? What where you using for a clamp? "ear" clamps, double ear clamps, hose clamps? I assume it was a barbed fitting? Did it take a bump? Just wondering as I'm going to use ear clamps on my barbed fittings.

Mossyback

That's the question that I've been asking myself. The only explanation I can come up with is that when I re-assembled the unit after doing the mods, I didn't use the clamping tool on that particular "ear" clamp. Those clamps really bite in on the barbed fittings and I don't see how it could ever come loose.

When I do anymore mods, I'm going to complete each hose at a time before moving to the next. When I assembled all of the hoses I'd slipped the clamps on and then slid them onto the barbs. The final step was using the clamping tool. As I said above, I guess I missed that one. It makes me feel really foolish.

Hank

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undrh2o

Well glad it wasn't more serious - I would think though that just the barb fitting wouldn't be enough to hold it on once pressurized and it would have come off when you turned on the tank. I think I will double up on the ear clamps - belts AND braces as Dave S and the brits say.

David Pye

Personally, I think my take on it would be that it demonstrates a few of the problems of having a shared diluent/bailout bottle.

One failure that both forces you off the Rebreather and knackers your bailout can't be good.

David

Dave Sutton

Loss of diluent ought to be a non-issue once at the bottom or ascending.... . No biggie.

Hank, this is why we call them "Bang Drills" in training.

The Oetger crimps when slipped over the hoses and not crimped will hold "For a while". Looks like you found out what defines "a while"!


Dave

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Dsix36

I am just glad that you are here to feel foolish. It could have ended a lot worse.

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Mossyback

David,

I agree that sharing diluent/bailout is a problem and I'm working on a fix.

Dave,

Now that I know what defines "a while" I won't have to test it again.
Understand that you're heading for the Doria soon. Have a great trip!

Dsix36

Yup, feeling foolish sure beats the alternative.

Hank

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Corallaro

Hi Mossy

see my old link:

http://www.rebreatherworld.com/home-...tml#post121281


in my configuration the real big limitation can be the 1,3 litres of internal O2 (i use it at 200 bar so 260 litres of o2)

also for this i made the pressure pot to test the cells with another bottle of o2 just before i dive

i use an external diluent/bailout/wings/drysuit (a seven litres bottle) connected with the original quick disconnect of IDA

i also have a 1,3 litres of internal diluent/bailout/wings (not drysuit).

if i want i disconnect it, also when i diving, to have two separate circuit,

i think that is the maximum of versatility

for more deep dive, i think to use a couple of three litres bottle (diluent and oxigen), connected at left and right of IDA and a totally separate bailout

for hose connection i use a stainless "snail" clamp, or rapid connection (aingep push in fitting) for rilsan, or standard air hose connection (seen near manual o2 and manual diluent)


Giovanni

david_1

I just got off the phone from oetger, there about 5miles from where I live :-)

but was told to use one ear clamps and not two, because two ear clamps have a more common failure rate ???

so to clamp on reg hoses what size and type should I be buying ???

Many thanks Guys