Appeared in DIVER November 2006

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REGULATOR Aqua Lung Legend Glacia

AQUA LUNG UK MADE ME WAIT until the temperature was cracking the flags in the July World Cup heatwave before sending me the Legend Glacia to try. I thought that was strange, because its a regulator designed for use in the coldest water.
When air is depressurised, it loses heat. You can easily demonstrate this by opening a tank valve and seeing how cold it gets as the air escapes. The problem is that the drop in temperature when the water is already cold, such as you might encounter at a freshwater site in winter, can cause ice crystals to form, and these can interrupt the efficient working of a regulator mechanism.
An uncontrolled free-flow ensues, with exponential effects that can cause a regulator to ice up completely.
This leads to rapid curtailment of a dive. Go to an inland site such as Stoney Cove in winter and you may well witness the occasional diver surfacing in a cloud of bubbles, warmed up only by uncontrolled expletives.
Years ago this was an uncommon sight, because regulators could not deliver the flow-rates of their modern counterparts. The greater the flow-rate, the greater the temperature drop. Earlier designers used more metal to make regulators - and metal acts as a good heat-sink, transferring what little heat there is in the water to the much colder air inside the regulator.
The techno-polymers commonly employed today do not. The best clue to having dives without free-flows in winter is to use a regulator made of metal.
The Aqua Lung Legend Glacia uses a high-performance diaphragm-type first stage that is environmentally sealed, keeping the works dry so that no ice can form. The downside is that it does not allow the air to be warmed up by the water.
Aqua Lung has countered this by fixing the first stage with a large metal cap with no fewer than seven huge finned metal heat-exchangers. It has the look of the block of an air-cooled motorcycle engine.
Another finned heat-exchanger is incorporated in the medium-pressure hose, the first time I have seen such a thing. It seems like a good idea. Another is incorporated where the hose joins the second stage, in common with other Apeks-made regulators.
There is also a metal baffle in place of the more normal sintered filter. Im not sure of its function but I assume it also acts as a heat-sink on the air that comes directly from the tank. I had some difficulty in getting a good seal on some
A-clamp-type tank valves, and attributed this to the baffle being quite proud.
Most noticeably, the second stage has an all-metal front to its otherwise plastic body. This should warm the air a bit more and stop icing occurring at the second stage.
The surrounding water may be cold, but if still liquid it will be a lot warmer than the air passing through it.
I suppose Aqua Lung could have gone the whole hog and made the second stage completely from metal.
Its no good having all these design features if your octopus simply goes into free-flow instead, so there is a dedicated octopus rig with identical features, and this would seem an essential part of the kit.
There are precautions to take too, when diving in cold fresh water. Not inhaling from or purging a regulator when it is out of the water is one. This will make the regulator very cold in the already-cold winter air, and it is then set up for ice to form as soon as it gets wet.
Avoid big flow rates by not purging or even letting anyone breathe from your octopus (unless its a matter of life and death) while submerged. Dont fill lifting bags or DSMBs from your primary air source. Use a DSMB with its own little cylinder.

I tried to convince the Editor to finance a trip to a wintry southern hemisphere diving destination such as South Island, New Zealand or even Antarctica to test the Legend Glacia, but he seemed unimpressed. So I took it to Wraysbury Lake, and guess what It didnt freeze.
I then took it to the Med to try it at depth and it didnt freeze there either! So all I can tell you is that, of all the regulators made by Aqua Lung and its Apeks subsidiary, this one looks to be most suitable for use in cold, fresh water.
A simple venturi plus/minus switch controls the position of a vane within the airflow of the second stage, disrupting the venturi effect should that cause an exponential free-flow where air meets water at the surface.
A fairly wide exhaust-T ensures that exhaled air does not interfere with the vision of a stationary diver, and I particularly liked the provision of a Comfobite mouthpiece (which is interchangeable with the conventional mouthpiece also supplied) with a lip-guard thats intended to keep the mouth warm.
This also keeps man-eating plankton at bay, which I found useful in warmer waters.
One cautionary note, however - I found that by pushing up on the nose pocket, the mouthpiece interfered with the ability of some masks to make a good seal.
After enduring one dive with a continually flooding mask, I had to remove it.
The Legend has always done well in our side-by-side regulator comparisons. Its sibling Titan Legend was well liked when we used it in Sweden in winter.
The Legend LX Supreme was a favourite during an earlier Red Sea deepwater test of top-price products, and the ANSTI machine test on it afterwards demonstrated a very low figure for the work of breathing.
Aqua Lung has added to this success with even more safety measures, and as such the Glacia represents the acme of designed-in precautions against the effects of freezing.
The Aqua Lung Legend Glacia complete with dedicated octopus-rig costs £442.
  • Aqua Lung UK, 0116 2124200, www.aqualung.co.uk


  • Divernet Divernet
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    + Upgraded to cope with cold conditions


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    - Second stage is only part metal
    - Mouthpiece guard can interfere with mask seal