First stage regulators for rebreather

spacemanspiff1974

What are most people using for first stage regulators for o2 and diluent?

I've read that the scubapro mk2 is used sometimes. It doesnt seem like it would be difficult to o2 clean the thing.

How does one plug the mk2 to prevent depth compensation? I've seen websites which show how this is done with apex and poseidon, but not the mk2.

Also, does an unbalenced piston pose the same problems with a rebreather as it does with open circuit?

Thanks.

DepthCharge

I take it that you are planning a KISS type? You can make a mk 2 non-depth compensating...........but you'll probably spend enuff money doing it to buy a couple of apex's or poseidons. Diaphram regs are much easier to convert......only one area to have to plug.
If you're planning a eCCR or mCCR then you will want (for the most part) to be depth compensating.
Or did I misunderstand your question?

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John

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zepp

I found the DS4 to be the best option, easy to make non-compensating, and easy for cleaning.

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Gibbon

The MK2+ is not balanced in the first place so what do you want to plug and why?

Yes they are very easy to O2 clean and work on in general.

Whilst I accept that the Mk2+ is not the smoothest regulator in the world, I have dived OC quite deep on a Mk2+, lets just say that the ambient pressure was approaching the IP - and there was no He to thin the mix. I know of people diving them deeper still with He in the mix. Which makes me curious as to what problem you are inferring about diving Mk2+ on OC, do you need more than 2500 liters per minute?

denzel

Hi Gibbon,

have a look at this thread as for the difference between unbalanced and non depth compensated, 2 very different things..

http://www.rebreatherworld.com/gener...ccr-depth.html

As for which st stage, DS4 hands down.
Affordable, easy to clean/ maintain, and the disc to make it non depth compenstaing is for sale from different places. ie narced@90, tecme....

denz.

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Philippe GERIN

Apeks DS4 as you can buy plugs already made.
I've had success with Mares MR12 + coldwater/antifreeze kit + rigid plug replacing the blue flexible antifreeze membrane.
But I still use Apeks DS4 because I use Apeks DS4s and DST on all the rest of my gear.
Best
Philippe

Gibbon

Doh, Thanks for that

spacemanspiff1974

Thanks for the info. Still trying to learn as much as I can.

Just to make sure I understand a few things....

Depth compensation on the o2 is ok for an ECCR?
On an ECCR there is no constant o2 flow but it only comes from the solenoid?

Am I incorrect?

Gibbon

Yes that is correct.

whoizrob

You could modify the Cyklon regs. Seems like you could machine a new cap for the reg to prevent the diaphragm from seeing ambient pressure.

Also looks like Oceanic CDX-5s could be a viable candidate.

There are quite a few regulators you could modify but the bottom line is that you'd have to create some new parts which could end up being pricey and unless you have access to a lathe you may be SOL.

Having said that, why reinvent the wheel? The Apeks route is tried and true and easy to work with.

Rob