caustic cocktail

Tom Rose

Not surprised....one of the first steps in anodising is to use a wash of caustic to remove the natural oxidized coating on aluminum....

Tom

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The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time.

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Tom Rose

Preventing and dealing with unwanted water in the loop...the cause of the cocktail....is of course the answer. Different brands of rebreathers handle those problems differently.

A few years ago I decided to take a different approach...that really works...it can stop water in its tracks with a little creativity on your part.

DIHYDROGEN MONOXIDE SCRUBBER

Subsequent to that posting I had a humerous...to me...incident at about 65 feet of water diving on a highly modified RGU....the hoses were too short...or the RGU is too low.....as you can see here...not the best configuration I ever set up as I was going to find out.



I was coming out from under a shipwreck...looked up...and there was just not enough hose to handle it....the mouthpiece came flying out of my mouth and lots of bubbles came up from the mouthpiece as the inhale hose emptied and the exhale hose flooded....Tony, my diving buddy saw it and saw the bubbles coming out of my mouth...he came screaming down towards me not knowing I was laughing at myself....I simply turned off the DSV and switched to OC...since I avoid decompression obligations like used car salesmen....

...No problem...and cut the dive short.

I had installed one of my watertrap packets in the bottom of the RGU scrubber.

I eagerly opened the scrubber to see if it had worked....there was no free water in the bottom of the scrubber....the scrubber material was in fine shape....I could have finished the dive...Better safe than sorry, I thought, but I now make sure that in my homebuilds, there is a place for a bag of the crystals in the exhale counterlung. It really creates peace of mind.

One tip....if you dive a lot make sure you stock up in summer, because the stores stop carrying it in the fall.

They say you can redry the stuff, but I just throw it in the trash. I do keep the bags.

Tom

__________________
The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time.

www.atlimp.com

Dave Sutton

This is great stuff, and has been a stock "trade secret" for the inside of the CL on my BOB since Tom first published his little missive. No lathe needed.... thanks Tom! Another "atta boy".

These mishaps are *bad*. Another reason for a BOV to be standard stuff. Had a LAR-V packed once with old 'sorb, and the fine powder managed to wend it's way thru the screens. I inhaled a (small) amount of the powder and I thought I was gonna die. I noticed it within about 5 minutes of entry, but thought I'd tough it out (stupid me). After 10 minutes I was in a full blown "I gotta get out" mode and it took another 5-ish minutes for me to get back to the exit (it was along a very rocky shore with big surf breaking... Jay Harding: Hazard Avenue, left entry). I took a week too feel 100% again. No joke, it's not fun. Cannot imagine a full mouthful of liquid, be a catastrophe.

Dave

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"Changes in Lattitudes, Changes in Attitudes, Nothing remains quite the same".... www.nobubblediving.com

jmurba

Hi gibbeo,

before the liquid got in your mouth hadn't you notice a gurgling noise ?

the rare time I experienced water intake in my circuit I was warned by a gurgling indicating clearly that a big amount of water had entered the loop and I switched to opened circuit before "breathing" liquid.

regards

jean mi

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when will I be able to think about something else then spending hours underwater, when will I be normal ?

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gibbogeo

No, i didn't noticed anything abnormal. Only some small gurgling in the exhale hose, but i allways had this gurgling in long dives or if the hose was still wet from a previous dive.

I wasn't aware of the problem until the mouthful. Maybe i didn't noticed it.

One thing was different from normal: i rolled on the right frequently to check my buddy that was behind me on the left. Maybe i pour the cocktail from the water trap directely in the inale hose.

Tom Mount

Tis, the nature of a caustic to catch us unexpectedantly- I know on the occasions when I have had mild ones, at times thought they were bad ones up until I witnessed a truly bad one- Yours I would classify as mild even though it may not have felt mild.

The one we discussed with Peri earlier was a REAL bad one, Glenn Forest had a real bad one, and I know of about three other dives including Joe Odom who had real bad ones. These usually result in shutting down airways and producing second and third degree burns or worse-

I have recommended to most manufactures that they invest in the use of hydrophobic membrane in the scrubbers- in axial this can be a membrane pad on the entry and exit sides of the canister- or some may look at a Cis Lunar style canister.

Unfortunately most manufactures do not fee the low risk is worth the investment –

I think if the report below is correct we should really read it carefully- it would certainly appear this could have been a caustic and the rapid ascent would be totally in character with a caustic cocktail- the description itself is about as perfect one for caustic as I have ever read.

Food for thought – I’m hoping to have some hydrophobic pads made for all my units and some how find a way to even use them with the micropore cartridges as both Glenn and Peri were using the cartridge with their caustic cocktails., even though it is more water tolerant that sorb or so it is stated-

I would like to encourage all on this list torequest that the manufactures produce hydrophobic pads for their units to lessen the probability of a caustic- thes of course would be and we accept them as options to enhance our safety- They will most likely make a slight increase in breathing resistance

Below From the accident and incidents thread-
Roberto Delaide - fatality
He surfaced calling for help.
Wife and friends did see him by a boat.
Quickly came rescue teams and friends (the latter swimming).
Any effort was useless: the diver was cianotic and swallen, dilated thorax, he was spitting caustic cocktail.
Also the neck was swallen and he was diving solo.

Three hours later at the police station we opened the reb. The canister was full and purple. Diluent bottles were empty and there were 60/70 bar of oxygen. We switched on his vitek computer running again his dreadful profile: after 13 minutes he was at 100 meters, after a while he reached 109 meters and in about 1'30" he surfaced.
He had a 10/70 tmx and a 80% nitrox bailout tanks full. Probably he had not the chance to use them.
We didn't extract the cartridge. We only saw from the top that it was flooded and purple but consider that he remained 40 minutes without the mouthpiece.

Ben Field

[quote=Tom Mount;115899]and some how find a way to even use them with the micropore cartridges as both Glenn and Peri were using the cartridge with their caustic cocktails., even though it is more water tolerant that sorb or so it is stated- [/quote]

Hi Tom, thanks for the imput,

Very interesting comment on the EAC, I've been told they are flood recoverable. I assume in the cases you mention there was either extended flooding and/or a breakdown of the EAC structure?

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RonMicjan

Back in 2004 when I was still diving the CCR dolphin, I took a pretty nasty hit, no warning, no gurgling, no smells, just one breath air, next breath "drano". read about it here -->tmishop.com/causticcocktail.htm

I dont recommend onboard bailout anymore BTW : )

someone asked about floods on megs, AFAIK, there has been none reported, excepting one where the diver had failed to thread down the nut on the exhale hose leading into the meg head, the hose blew off on ascent.

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Tom Mount

Hi Ron

As you know I flood and recover on the Meg as a demo

But I did have a person get a caustic on the Meg- his fault as he descended on OC(for some reason) and switched to the meg at depth- at 25 minutes at 100 feet (30 meters) got a hit but not as bad as yours- was able to bailout out and ascend do deco and then surface- had burning even after rinse with coke and use of homeopathy for a couple of days but dived anyway- again his fault and many of the caustics on all rebreatheres are the dives fault

I agree 100% on the bailout mouthpiece if one has a caustic, as when they baillout they again breath the caustic-

AD_ward9

There are three issues here:

1. Risks from hydrophobic pads. Which material would you use? All increase WOB, some a lot more than others, and if the user packs the material incorrectly, the result can be serious. The Stone Aerospace cartridges are not designed for the chaotic environment of sports diving, and some of the things sports divers do.

2. EACs with electronic flood detection are a solution. EACs take tens of minutes to reach dangerous pH levels, compared to 30 seconds with granules.

3. The granules themselves. Just a month ago there were posts explaining how it was not a clever idea to use medical grade granules, yet in this very sad accident, that is just what was used. If there is a CO2 hit before the flood, which is almost always the case, the diver cannot deal with it. Those granules were not appropriate for diving. There is widespread ignorance of what absorbers do with increasing levels of CO2 flow: many shut down giving huge CO2 spikes. Divers are doing these changes without the faintest idea of what it is they are actually doing. Training organisations have a role to explain this to their students: i.e. do NOT mess with granules other than those the unit has been designed for and tested with.

I had a complete flood and caustic cocktail on a rebreather 6 years ago due to a design fault on the equipment (that is still there on units sold today). The accident was enough for me to take a lot of interest in Micropore's products. The CO2 hit that goes with a flood makes one far less able to reason about a caustic cocktail. I thought it was caustic coming into my nose, but that was an hallucination under the CO2 hit - my nose was in a half mask. Fortunately I was very close to the surface, I did bail out - albeit much too slowly, and the boat came fast. If I had been deeper, I would have been gone.

As regards low risk not needing the investment: caustic cocktails are not low risk, not are they infrequent. The problem is caused by incompetent safety design IMHO.

Simon's post shows the critical nature of these failures, as do the accident lists, and posts such as yours, Rons and others, show it is not uncommon. I cannot see how on earth any manufacturer can defend not dealing with these issues. Perhaps manufacturers on the forum could enlighten us?

Alex