Counterlungs

Dave1w

Having 2 odd sized like the dolphin, can anyone think of Pros/cons of having the exhale larger than the inhale?

Initially SCR, so dosage is on inhale (and ADV would be). The larger exhale gives a bit of a water trap too.

Dave

Marc T

A exhale counterlung bigger than the inhale will give you an increase WOB, I cant explain that but it is a fact ( playing with a Rebreather with chestmounted CL, and squeezing alternatively one or the other CL you will soon understand )

Water trap dont need to be so big especially if you can evacuate water, AND a water trap ( inhale CL with perhaps an absorbant pad is usefull AFTER the scrubber to avoïd drinking some accidental caustic cocktail.

Last point is that I used ADV on the exhale side on several of my Rebreather prototype, it works fine and have some advantage to flush the loop

Dave1w

Thanks Marc for the info. Interesting about ADV on the exhale. At the moment, not good for me, as I am starting with SCR so I can get the nuts and bolts right.
I am running out of water bags to cut holes in.....
Cheers
Dave

montyg

What does general opinion (or maybe empirically derived wisdom) over here in the home build forum say about the ADV on the exhale side of the scrubber in terms of scrubber performance & dwell time, etc

1)One could argue that the ADV being in the exhale side, will dilute the exhaled gas in the Rebreather before the scrubber, thereby increasing dwell time and thus increasing scrubbing.

2)One could also argue that the ADV injects cold gas which decreases the scrubbing efficiency, and that it maybe increases gas velocity through the scrubber, which is a further reduction in efficiency?

3)With the ADV in the exhale side and a total scrubber flood, it would render a CCR completely useless in the sense that you couldn't even nose-breathe and bail out in SCR mode, because the ADV wouldn't be activated by your inhalation or the reduction in loop volume due to nose breathing?

rgds
monty

divetheworld

Bang on, especially number 3.

B

__________________

Marc T

Point 1 and 2 are not very important, especially in CCR the diluent flow is not constant and generally speaking quite low so dont mater.

The point 3 is more interesting to discuss:
- first the ADV works exactly as if it was on inhale CL, if he is onthe inhale CL he will nut "fire" if the inhale AND exhale CL are not empty at the end of inhale cycle so it doesnt change anything.
I accidentaly test that this WE in a test dive when flooding the Rebreather I was testing, had a soft caustic cocktail ( Medisorb ) that I was waiting because of gurgle, rince my mouth then back on loop with higher volume in the CL and it was OK. Back on land, God there was caustic cocktail in any part of the RB.
Secondly if ADV on exhale you can completely flush the loop in case of O2 spike.

Third flooded loop is flooded loop dont stay on it on a real dive

For me I always listen to other guy's experiment, but I try too