Back Mounted Counter Lungs
 ***UPDATE OCTOBER 2012: Ambient Pressure Diving has launched CE tested Back mounted counterlungs at EUROTEK 2012***

Paul Channing's Inspiration with back-mounted Lungs
Author: Paul Channing
Published: 20-02-2006

Pictures say a thousand words, so I’ll keep it brief. I designed and fabricated a stainless steel box that sits snugly between
the box/ wing and the back plate:
The unit sits 50mm back from its original position.  The s.s. box provides a useful means for stowing various bits and pieces out of the way:

This shows a suit inflate bottle (just), snorkel (don’t ask), a big spidge bag and an emergency blob all tucked away and readily accessible.  This works for me as I have found that when gas-diving, the quantity of ‘things’ I like to carry can breach a critical point – now I don’t look like a Christmas tree..!! 
Excuse the rubbish in the background btw.

Standard Inspiration lungs are used for both ease and to keep the cost down, albeit with a few bits removed:

Now for some pictures of me looking silly, diving at 1 atmosphere ;-)

How it sits to my right:

How it sits to my left:

Putting stages on is very simple as I can see what I’m doing:

For the extra bits and pieces that I need for gas diving, a Joey Pouch, clips from the bottom of the backplate to the waist-ring.  All my equipment goes on the right, gas to the left and a Q40 shines directly over the handsets to the right – just like good old OC

As I’m right handed – all the gear is accessed with the right hand.  The left stays with the torch and reel – making easier work of the task loading on descent/ ascent – i.e. no need to swap hands to get to kit.  You can see how the box doesn’t dig-in to my arse at the base:

A view from the left shows the profile of the lungs:

Valves are accessed without any noticeable difference:

Short of a slave, maintenance doesn’t get much easier than this:  :o)

No manual o2..??
In the above photos there was no way of manually adding o2, however this has now been remedied:

I considered various designs and believe this one to be the most simple, elegant and cost effective.  The buzzer tucks-in nicely behind too.

The design uses standard APD fittings throughout, making replacement straightforward.  I have added a water-trap to the ADV T-Piece and had a ‘converter’ made to marry the o2 add to the T-Piece.  The only physical change to the T-Piece was to plug the hole:

Detail and thoughts:
  • Diluent flushes can be facilitated via pressing the ADV diaphragm.
  • The lungs remain effective water traps.
  • WOB is, as far as I can tell, no different, but this may be because of the profile of the lungs and the fact that we breathe ‘off the top’ of them - I don’t dive on my back so I haven’t had ‘hamster cheeks’
  • The position of the lungs has done two things:
-           The T-pieces are further apart – before I always felt quite encumbered and wrapped-up, but now I feel I have much more freedom – not so tight or restrained.  However, the lungs can be threaded over the harness if desired and returned to their original position. 
-           The position of the lungs seem to put me in the water much like a wing  i.e. horizontal, this is in spite of running minimum loop volume.  
  • The dump valve toggle is extended to sit over the shoulder and actually dumps better when horizontal due to its upward facing position.
  • The lungs are, to an extent, protected, certainly more so than before.
  • Maintenance is an absolute joy.
  • The s.s box creates a relief at the base, so the unit no longer digs into my arse - no more lower back ache on long dives!
  • Kit can be stowed more effectively, making better use of that little more space.
  • Kitting up and putting stages on is greatly improved.
  • The backplate and harness can be removed independently of the s.s box and transferred to OC - much like the KISS (not that I would of course ;o)
  • The pressure gauges are a typical scuba length (whatever that is) and are there for the convenience of pre-dive checks – otherwise I’d use button gauges.
It seems just like OC diving - an unencumbered clear chest with good access to what I want.  However, I can’t crush the lungs anymore for diluent or o2 flushes, but it works quickly enough nonetheless, and hey, gas is cheap right! ;o)
Please feel free to ask any questions or contact for package details:
Paul Channing
Paul thanks for contributing to my website!
 ***UPDATE OCTOBER 2012: Ambient Pressure Diving has launched CE tested Back mounted counterlungs at EUROTEK 2012***

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