BIGGER, BETTER, SMALLER, LIGHTER; these are all claims commonly made for modern consumer durables.
Regulator second stages used to get smaller each time new models appeared, so that they were lighter in the mouth. Then someone realised that a large front area that allowed water to pass freely on to the pressure-sensing diaphragm actually made the regulator respond more quickly, and hence breathe more easily.
Suddenly, the latest second stages grew bigger again. Not only that, but lightweight technopolymer second stages were found not to have the heat-sink properties that were essential for diving in cold, fresh water.
Thats something a lot of divers do in winter when they cant afford to jet off somewhere warmer. Manufacturers started adding metal parts, and some went the whole hog, making the complete unit from metal.
On the other hand, the popularity of diaphragm-style first stages, probably the
result of the same cold, freshwater diving requirements, grew until even the most committed proponent of piston first stages produced a diaphragm design, and a very good one at that.
The fashion among British divers has been for those diaphragm first stages that are dry-sealed, so that the works are protected from dirty or polluted water.
In fact, few of us actually dive in water so affected, but even manufacturers such as Mares, which makes an add-on environmental sealing kit (for the Proton Ice Extreme) now uses the term coldwater kit, in deference to contemporary custom.
These first stages have often become unnecessarily massive. Airline baggage allowances, and a feeling that the Victorian fondness for over-engineering went hand in hand with poor ecology, means lighter is now seen as better.

First stage
Mares has been at the forefront of this drive to cut out excess weight from its chrome-plated brasswork. It has gradually pared away the metal from what started years ago as the rather clumpy MR22 first stage (still available for those who want it). Passing through ever-reduced designs, including the VR32 and little V42, it has culminated in this latest 42 version.
The 42 is now so small and lightweight that it looks positively dainty, and rivals many worthy titanium-made regulators when it comes to packing weight.
It still has the successful hose-routeing of its predecessors, with four medium-pressure ports angled slightly away from each other, and two high-pressure ports angled steeply downwards.
Fears that the machining may not have left enough metal around the lower ports to avoid damage during rough handling seem ill-founded, and a diaphragm first stage like this should have no greater tendency to freeze up in cold water, despite being without environmental sealing.
Dynamic Flow Design (DFC) keeps the inter-stage pressure constant during the breathing cycle.

Second stage
This is the latest incarnation of the long-established Abyss, which the manufacturer calls its Hero second-stage. It has been face-lifted recently to make it sleeker-looking than previous Abyss second stages. Even more metal has been added to the front cover and hose-protector, to help conduct heat from the water to the very cold air reduced to ambient pressure from when it was in the cylinder.
A unique-to-Mares all-metal bypass tube avoids fast-moving air crossing behind the pressure-sensing diaphragm and causing exponential free-flows of gas, so no venturi plus/minus switch is necessary. Mares calls this a Vortex Assisted Design, or VAD.
Similarly, Mares designers do not believe that divers should need to increase the cracking pressure of the valve manually with any breathing resistance adjustment. Just inhale less energetically if you require less air.
A pleasant side-effect of having a metal second stage is its resistance to damage when
a less-than-careful dive-boat crew plonks a heavy tank carelessly on top of it.

Purge Control
This is easy to find, even with a gloved hand, and it works progressively but effectively to clear water from a flooded mouthpiece.

A lot of rubbish is talked about all-metal regulators, to the effect that they might be heavy in the mouth. This may seem so in a dive-shop, but once under water the buoyancy given by the air contained within the second stage makes it virtually weightless.
Mares has managed to coat its chromed brasswork here with a layer of soft polyurethane, covered in a second harder layer that gives it a durable finish.
Im pleased that the men from Mares seem finally to have done away with the floppy mouthpiece that made holding onto their regulators slightly more arduous than was
really necessary.
I used this regulator in some fierce flows of water. They may have left me heaving for breath due to lack of fitness, but the regulator always performed faultlessly. It never over-breathed, nor did it cut me short of air when I needed it.

You should expect to find a total work of breathing - thats both inhaling and exhaling during one cycle at 50m depth with a tank pressure of 50 bar - of less than one joule per litre of gas. Thats very good, and up with the best-performing regulators currently available.

Scubapro Mk17/G250V, £339
Apeks XTX40 Status, £362
Aqualung Kronos Supreme, £300

Divernet Divernet

COST £370
PORTS 4mp, 2 hp
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%