Scrubber bypass Ida-64

robertfondren

Thank you all. Ultimately the 64 never materialized. Sigh. But I've now graduated to the IDA-71 anyway. Since many (most) of the Ida -71 Kiss conversions usually do away with one scrubber, I'm thinking of removing the h-piece inside the lung, and just running an internal hose to one scrubber, assuming, of course this can be done in a suitably non-destructive fashion...

osiris

Yep, should be able to be done. My IDA-64 looked like these pictures. The IDA-71 and IDA-64 are pretty much identical in this regard. You'll find twine, wire and steel clips used (maybe other methods for all I know).

If you're not thinking of increasing bore diameter to help WoB, then the hose you took out should be Ok to put back in with appropriate fittings.

Someone on this site was thinking about putting a exhale lung inside the CL as a water trap - not a bad idea and one I'm looking at (Drager Dolphin exhale bag is what i am thinking off).

I've managed to get the Russian valves off the 1.75Ltr cylinders and I have a 3Ltr dumpy for use a a dil. Both have "Kleinkonisch" threads. Go to tecme.de for the valves.

I'll be interetsed in your prgress..
cheers

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Dave Sutton

Guys:

Speaking as Franken-Rig's Daddy:

I made a huge mistake when I built up the first IDA-71's with one scrubber removed. Yes, they work. BUT!! I *personally* and several others have reported hypercapnia at relatively shallow depths while using a one scrubber configuration. One scrubber is simply not fully adequate. I might be "partially" adequate, but you WILL get a C02 hit one day if you persist with this. Hypercapnia is the ONLY thing that frightens me on rebreathers and i the only thing that has ever caused me to actually believe that I might die underwater. Don't play games here.

PLEASE reconsider the removal of one scrubber. The best bet is to place the 02 internally, use both scrubbers, and simply connect your bailout bottle to the rig with a quick disconnect hose thru a checkvalve and to use that offboard bottle to act as the rigs diluent supply as well. Since you ought not to be using it without bailout anyhow, it's a no brainer. Just think out of the box a little and you'll see that it works fine.

Please?


Dave

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undrh2o

Dave is the square scrubber (modified for kitty litter) any better in this respect? Is it acceptable in a single scrubber setup?

carcharodon1957

Hello,
another 2 cents to add for thinking!

Any way you choose with one or two scrubber, but consider (if you dive in cold water) that internal (threw the bag) tubing will keep mixing gaz warmer for CO2 captation process and also your breathing comfort!

My point of view lead the way for one scrubber,removing the T tubing and replace with a PVC piece!
Using my IDA 71 at max 85m, in soft water makes me 2 hours dive and had not yet any CO2 hit !

Talking about 130/140 dives.

Of course, never say never, but most of the time no current, low effort just because no huge distance to swimusually in lake.A rather good knowlegde about my metabolism with Rebreather since 25 years!

I'm of course not a example, but I know a little from CO2 hit on me (tested it on O2 Rebreather) help me to change sorb at each extended dive (more than 20m)
always removing dust before and tap the scrubber (but softly like on baby back after his lunch)

regards
Bernard

Dave Sutton

Dunno... once I had one HYPERCAPNIA (original post inadvertantly had HYPOXIA) incident with a single scrubber, I went to dual scrubbers and never did further experimentions.

My HYPERCAPNIA issue took place at 130 feet in 50 degree (F) water, immediately after a fast descent from the surface. I had been swimming hard down the anchor line after a hard surface swim to the bow of the boat in a current.


Dave

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carcharodon1957

Hello Dave,
sorry (probably more silly what I imagine),

but how do you compare hypoxia and and CO2 hit?
Just because origins are not the same!!!

Your hypoxia came from O2 line, and CO2 hits comes from brake in CO2 absorption procedure by sorbs (for many reason)??

Or maybe am I wrong since long time?

Thanks to explain me links if theres any crossover between them, except accident with both reason.

sheers
Bernard

Dave Sutton

Thanks for asking, the fact is that I mis-typed the reply.

I INTENDED to write HYPERCAPNIA

I instead wrote HYPOXIA.


I'll go and edit the above post with the correction in red to show it was made.


You are, of course, correct, but I will not address the questions as they are only based on a bad post by me. Sorry!!

Dave

Skipbreather

For those of you wondering what all the fuss is about: I dove a single scrubber ’71 off and on for several years. I’ll not get into the mechanics of why, just into the “what”.

99.5% of the time all goes well on a single scrubber. Fresh sorb, cold water, 3 hrs no problem. The operational issue is work output (= CO2 production) from the diver. At normal (whatever that is) work levels scrubber keeps up fine. Put on a burst of speed/ effort with those thigh muscles cranking out the CO2 and as soon as it gets from the body to the loop count on the ‘dark narc’ of a low level hypercapnic situation developing. Stop & let the scrubber catch up and situation will right itself in a time span proportional to the amount of scrubber overload. A dil flush would most likely speed things up.

Most challenging of all is the double whammy situation where I took my worst CO2 hit: Hard swim at 30m from one end of a 250 ft long wreck to the other followed by immediate drop to 40m to penetrate at a known entrance. A short way into the wreck it all caught up to me and it took every scrap of self control gained in several decades of diving to avoid doing something exceptionally stupid and deadly until the scrubber caught up.

If you dive a single scrubber setup, be aware this probability is very real. Have a mental plan to deal with it ready and thought out in your personal ‘bag of tricks’ or you WILL eventually have a VERY bad day.

Ken

__________________
"Entropy RULES! Enjoy the interim."

Corallaro

Hi Guys
My personale experience, i use IDA-71 only with two scrubbers.
A dive in a wreck, +- 33 meters (in this dive for a problem i use my oldest little inefficient fins)
The wreck ancourage i failed so, with my buddy in OC, we search the wreck...and finally found it but, the time to se the vessel and my buddy tell me that is the time to go back.
An hard swim aganinst a strong current, my buddy (with only a 15 liters bottle and the righ fins) went like a rocket, I NO!!!...
I arrive at boat with my heart in throat,,, a very very hard experience ...puff puff pant pant BUT, no any trace of hipercapnia....
So i think,,, if my IDA don't kill me in this dive dont kill me never.....and in his original configuration is a very good reb....

Giovanni

PS
(lesson learned: don't dive under 15metres with a buddy with o.c. even if your buddy is your reb Guru)

(II lesson learned: even if you broken your drysuit, when you think to have a dive around 33 metres with a buddy in O.C. don't use your old little fins even if they are the only that you can use without drysuit shoes) ....

(III lesson learned: if you don't learn the previous lesson...use IDA-71 only with two scrubbers, this can save you!!)