Rebreather AP ADV
Louise tells me I am not a proper diver. I use an AP Inspiration closed-circuit rebreather for the long durations possible at depths in the 40-50m range rather than to dive deep wrecks, as she does. However, it works for me! I may not be proper but some of the conditions in which I dive are quite arduous, especially when its necessary to descend quickly through the current to avoid missing the site.
  I like to keep the counter-lungs at minimum volume so that, as I inhale, they go flat. Of course, as one goes deeper you have to add diluent to make up for the increasing ambient pressure, and I used to have to do this by injecting small squirts by way of the diluent feed on the left side.
  However, with a camera outfit in one hand and perhaps the need to hold a downline with the other, things can get fraught. So how nice it was for me to use a unit equipped with an Auto Diluent Valve, or ADV, which sits in-line in the loop next to the left-side T-junction and fed from the diluent cylinder.
  I admit to having had a very unhappy time with an early prototype ADV. It kept leaking diluent into the loop when I didnt want it to, causing a severe case of hamster-cheeks, clearing all my nasal passages, and using 100 bar of diluent on a typical dive.
 I resorted to turning off the diluent tank until each time I needed it, entirely losing the point of it. It was a character-building experience. So I am pleased to say that the production model I used was as sweet as a nut.
  I was able to plunge headfirst off the boat at Cocos Island, and head down through the current with two hands free to hold on to anything I needed to. I simply had to heave a littleextra on the inhalation to pull open the ADV and let a little more diluent into the loop on descent. Lovely!

 I used the ADV fitted to a little CCR unit which bore the name Evolution. I am told that this was only an early bench-test model which will be nothing like the final product. It was made for demonstration at the last DEMA show in America.
 However, Inspiration owners will note that this unit uses a standard-style BC with integrated weights, and comes with a smaller scrubber unit and two 2 litre cylinders. I found that I used less than 40 bar of gas from each cylinder during a one-hour dive to 40m.
 It has a beautifully shaped case which makes installation of the scrubber and cylinders a dream and, under water, it requires less weight on the belt because it displaces less water, doing away with that diving-with-a-wardrobe-on-your-back feeling.
  What about extra open-circuit bail-out Well, as someone said, the trouble with carrying bail-out cylinders is that you will need to empty them before you get them tested each year, because you aint ever going to use them!
 The boys at Ambient Pressure Diving told me not to write about it because the final production version of the Evolution would be vastly different and even better. It will be bound to appeal to those of us who are not proper divers.
The ADV adds £159 to the price of an Inspiration from the factory. It can also be bought separately for £199 to fit yourself (said to be simple) or, for £10, by Ambient Pressure.
  • Ambient Pressure Diving 01326 561040, www.ambientpressurediving.com

  • Divernet
    The ADV can be supplied on new Inspiration rebreathers or fitted retrospectively
    + Evolution less cumbersome than an Inspiration

    - Evolution not available in this form