Scrubber on homebuild....

Genesis

Ok, so tell me why you don't just BUY the Micropore scrubber conversion for either the Azimuth or Dolphin?

I realize this leaves you with having to figure out how to do the sensor and injection block(s) outboard from the scrubber, but you get an inexpensive ($350) and KNOWN scrubber design from a manufacturer who has flow-tested it.

This + a DSV leaves you with figuring out counterlungs and the sensor/injection system - other than that you've got a diveable homebuilt.

What am I missing here? Building a cannister isn't exactly impossible, but can you do it from scratch for less than $350 and know you've got the sealing/channeling issues handled? Hmmmmm.....

2stoned

__________________
Sten.

The only man that always had all his work done by Friday, was Robinson Crusoe!

www.rebreatherworld.com - Is going down in silence - Staying longer in stealth and style - Diving first class, all the way!

Genesis

Yeah, I read all that and understand it, given how the Micropore cartridge works and is designed it makes perfect sense.

But - they sell full cannisters for their carts - one for the Dolphin, one for the Azimuth - two SCRs!

So..... the engineering is already done - and its a bolt-up and go for $350. Not a bad price, all things considered.

This could be pretty significant as a development for homebuilders. Buy a DSV, buy the cannister, now you have to work out the counterlung arrangement (OPVs, ADV if you want one, etc), monitoring and injection/control. The "engineering" parts that require things you can't typically DO as a homebuilder very easily - especially those that require the ability to machine large parts like a scrubber can - are done!

I was wondering if anyone had a reason that using one of these would be a BAD idea. I realize that I'd have to come up with a separate (smallish) space in which to mount sensors, injector, etc, as those are not part of the SCR paradigm but are for a CCR.

But this nicely solves a number of problems typically encountered in a homebuild, especially if you want to use the Micropore cartridges - the fit is crucial as well as gas flow engineering, as you noted.

Also, does anyone have a good set of pictures of the Azimuth scubber (either theirs or the "real" one)... it looks more compact than the Dolphin in terms of its connections, but the picture they have up is not very good in terms of showing how it hooks up.

2stoned

Genesis...
I can see where you are heading.
Using parts already engineered keeps you from having to invent the wheel allover again and again and again…
There are many hurdles to conquer though…
Securing a good gas blending in the loop.
Perhaps feeding the new gas (or a bit of diluent now and then) past the O2 sensors to help keep them reasonably dry.

I have read your other posts, giving me confidence that you could maybe pull something like this off.

__________________
Sten.

The only man that always had all his work done by Friday, was Robinson Crusoe!

www.rebreatherworld.com - Is going down in silence - Staying longer in stealth and style - Diving first class, all the way!

Genesis

The mixing isn't that tough. There's already precedent on how its done - you can inject into the exhale side for O2, and into the inhale for diluent, which is how many commercial units do it (with the Meg being the notable exception.) Just upstream of the scrubber is the obvious place for the solenoid O2 feed.

The trick would be sensor placement to keep them from having condensation problems. I can think of a few ways to potentially solve that as well as engineering the rest of the loop components without having to need exotic materials or equipment but it would need field testing and verification - I would expect that the loop would by definition have near or at 100% RH all the time when in operation in the cooler parts, so the trick appears to be having the sensors where its warm thus keeping the RH - and thus condensation - under control.

Would love to see some good pics of the Azimuth scrubber can - the connections on the Dolphin one that Micropore has are long and would make a transverse placement of the cannister (behind the head) unwieldy...... The Azi model might be a better choice for that reason.

Then again that's part of the fun of homebuilding something eh?

Crazyduck

I refer to it as the evolution of 3rd party materials.
Or a Diverite rebreather; gee Wally where did they come up with that?

If someone wants a developed system there are plenty of them available.

Making something yourself – well that could be a little more interesting.
I think the nemesis of things not mentioned could be leaks--- nothing like pulling off a hose but things that just do not fit quite right. This was covered on the Wern website on the development of his hunchback rebreather.

Adding gas is no big deal- you can use various manners.
There are a few fashionable styles that come to mind.
Richard Pyle’s- I need some diluent, one mouthful at a time.
Will Smither’s- TP2000 low pressure inflator BC add system.
Dave Sutton’s- Spare Air add machine.
Tom Rose’s- The little RGM add valve that could.
And there are many more.


When using a axial scrubber the position of the sensor is going to be very interesting. Different groups have handled it in different manners.
Something to look towards.


Andrew