Counterlung Size/design .

colinicky

I have heard & read a lot about using minimum loop volume on my inspiration .I have also been told that when we do this we only use the top of the c/lung .So why do we need such big c/lungs ? Or is it a case that it is the only way to get the inspiration through CE approval ? If this is the case I am led to believe that the Boris has smaller c/lungs which are back mounted ?
So if the above is true is there any reason why on a back mounted conversion for the insiration that you couldn't or shouldn't make the lungs smaller ? say half size ? surely if you did this it would reduce WOB when in a head down position ?
Does this make sense to anyone else or am I & talking complete B****cks as usual ?

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Colin

I trust my rebreather completely ,
I just don't trust the user

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curator

I'd be interested in hearing replies also (i.e. I don't think your talking bol##ks).
I dive a Dolphin (total lung volume aboutr 6 litres) and have to suffer listening to my inspo diving buddys complaining about bouyancy problems. No surprise considering the size of their couterlungs (or am I talking bol##cks).

Cheers

Curator

pchanning

Hi Colin,

Matched lung volume is, they say, a nicer way to dive. I'd be interested if youre thinking of getting some smaller inner bags knocked-up

A normal Inspo lung could be adapted like this quite easily - ie shorten the length (thus size) of the inhale CL inner bag - there is a perfectly good diluent button on the side of the ADV, so it wont be missed. The bag would only need 1 hole in it for the T-piece.

Its an interesting thought that may provide a matched/ manageable loop volume per diver for minimum cost.

I have no idea if this would be the right CL to 'adjust' in terms of WOB etc. just an thought.

Perhaps the designer could comment.

Regards
Paul

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Paul

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Beanie

The counter lungs are sized to get the manual inflates in the right place the volume is nothign to do with it, the medium lungs are somthing like 12 litres?

and running min loop on them is not a problem even for tiny lungs me.

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colinicky

Beanie :- exactly my point minimum loop volume is easy which is why I posted this question surely nobodies lungs can take 1 breath & empty the counterlungs ?
Paul you said reduce the inhale lung why not both ?
Dave T has said we only breath of the top of the lungs ie were the T pieces are so do we need all the extra lungs ?

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Colin

I trust my rebreather completely ,
I just don't trust the user

onwards & downwards

Digger

I used to use medium lungs on my homebuild, and I have to say buoyancy on the KISS has been a whole lot easier. I was running MLV with the inspo lungs, but I had to think about it to get it sorted. On the KISS the difference between minimum and maximum loop volume is about half a breath, so getting it at or close to where I want it is easy.

If you backmount the lungs, why not just reduce the space availabel for the lungs to expand into? If there's a hard case of sorts like Paul's design then it doesn't matter that the bags are 11 litres if they can only take up 6 or 7 litres of space.

If I had an inspo or inspo lungs again that's what I'd do. I don't know why the lungs couldn't be much thinner, it would mean the buttons could be in the same place but lower volume lungs and it would clear up the chest area a bit.

Digs.

colinicky

So I suppose the next question is what size lungs do we need ? anyone know how many litres a medium inspo lung is per side ? Digger do you know the litres of the kiss ?

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Colin

I trust my rebreather completely ,
I just don't trust the user

onwards & downwards

Digger

KISS you buy the sizes to match your lungs, for most people this is 6 litres, one 4l and one 2l. The boris is 6l as well I think, seems to make sense to me.

I've not tried mine with 2 x 2l lungs, but I'd imagine from the range they have with 6l available it would be less than I need for a full breath.

Basically, if you could come up with a good way of getting the inspo lungs to 6l then you'd do fine to use them. That asid you do need somewhere to put the buttons. If you use Paul's method that's ok but there are consequences to moving buttons and changing the design obviously.

Digs.

Simon A

Colin, given the design of the inspo lungs, surely It's easiest to just make up a nylon cover for the bladder to restrict the botom of the lung and therefore alter the volume, that way you don't even need to get a new bladder made.

Simon A