Digger with Duncan Price

[Duncan Price]

Originally Posted by David

is there more details of this RB. and pictures it looks like fun :-0

http://www.sump4.com/rebreather/d5_construction.html

Needs updating as there are a few changes to design (no face hair, two sensors instead of one, more compact feed lines, changes to scrubber internals, moved placement of trim weights) but you'll get the drift - I have a lot of photos intended to add to this but its a start.

[NotDeadYet]

Originally Posted by Duncan Price

Driving two RB's when I don't need it just adds to task loading though I do like the idea of configuring a D5 as a semiclosed unit for bailout - would need to carry the right gasses to drive it and the primary rebreather also, with ppO2 monitoring and adjustable flow rate on the SCR feed this is doable to get you shallow enough to go OC.

The Swiss guys who built the EDO4 dive on twin SCRs with no OC bail out. They treat them like diving on OC independants, 15min on one RB, then switch for 15min on the other, then keep switching throughout the dive. They have some flexible hoses and Swagelok plumbing to make sure both rebreathers are running off the same drive gases.

I'd thought about building a semi-closed bail-out unit like a small RB80 clone running off a feed from my main dil. With that kind of design then it is automatically depth compensated so you don't have to worry about making any of the parts resistant to pressure. What put me off was the drop in ppO2 that passive SCRs have, it wasn't practical to be using the same dil as my main CC unit. I suppose you could do what Phi Le did and put a KISS valve and O2 monitoring on it but it starts getting complicated for a bailout system.

[Duncan Price]

Originally Posted by NotDeadYet

I suppose you could do what Phi Le did and put a KISS valve and O2 monitoring on it but it starts getting complicated for a bailout system.

Exactly - you need bailout more/as reliable than your main rebreather. I just use my 2nd unit as a spare rig that I can swop components between. After yesterday's dive I've got a part used scubber sealed up for a short dive and an empty scrubber to be filled for something bigger. If one component doesn't work than I can swop it out with a spare and fix it later.

[Digger]

Originally Posted by Duncan Price

Yes an ADV is just a butchered 2nd stage though I need one small and capable of running of a Poseidon IP. Ocenanic (I think) do a nice shower head job which migh fit the bill - anyone have one going spare? Needs to be upstream of the scrubber to work best though and there's not much space there. Have been investigating Swagelock catalogue for something that might work and be very small.

There's a guy advertising an Omega in Personals, think it was £40-£50 he wanted. Sounds reasonable, and that's the showerhead Oceanic. Fits standard hoses too, saving a few quid. I don't know about Poseidon IP for it though, I thought it was on lower, same as an Apeks or similar. I did hear about a guy who advocated using a delta 2nd on a jetstream, but don't know who he was and whether it's sensible.

The way your cyklons are detuned wouldn't you be able to just reduce Ip and lower cracking pressure a bit and use any 2nd stage? I've got a few knocking about if you need to butcher some. They're useless as regs to me, but might be able to work as an ADV.