ANSTI MACHINES ARE USED TO TEST regulators to ensure that they meet European standards. This means that it should not be possible to buy (in Europe) a bad regulator.
Martin Parker, the boss of AP Valves and Ambient Pressure Diving (APD), knows a bit about ANSTI machines because his company owns one big enough to get a complete rebreather inside. When we at DIVER carry out regulator comparisons we have often taken the precaution of getting the results confirmed by ANSTI test, but we get ANSTI to do the testing.
That said, Martin has pointed out that the shape of a mouthpiece can affect the work of breathing, and the flaw in the plan is that regulators have their mouthpieces removed to fit onto the ANSTI machine.
If you look at the mouthpiece of an APD Inspiration rebreather, you will realise that it is not interchangeable with the standard-size mouthpiece of any other regulator. Taking into account the extra weight of the CCR unit, the mouthpiece of an Inspiration is wider, with a larger exit hole than is standard.
This brings me to the Scubapro Titanium S600 MK25 regulator. It’s a fabulous device, the best that Scubapro can make when it comes to the ease with which it should breathe. Constructed in lightweight but super-tough titanium, it’s bound to become a favourite with divers who travel and suffer the checked-baggage limitations of economy-class tickets.
I took one with me when I recently went for an extended trip to the Maldives.

So what’s all this about mouthpieces Well, I found that this otherwise wonderful regulator was spoiled by its mouthpiece.
During dives I noticed that I could hear a slight whistle on inhalation. This combined to give a little more labour on my part than I was accustomed to.
Experimenting over a few days, I found that if I held the mouthpiece securely between my molars the work of breathing was more than if I let the mouthpiece lie loosely in my mouth.
This implies that the aperture in the mouthpiece, the exit hole for the inhaled air, was getting distorted during normal use and was not as efficient as it might have been.
If I owned one of these regulators, I would soon swap the mouthpiece for a better one, of a type fitted as standard to Atomic regulators.
When Gilbert de Coriolis, the Technical Director of Scubapro, reads this, he might send me a rude letter.
On the other hand, he might change the specification of the mouthpieces Scubapro fits. Let’s hope it’s the second option.
In the meantime, let’s get back to the main business in hand.

First Stage
The MK25 first stage is the pinnacle of the development of Scubapro’s long love affair
with piston-type regulators, and of course this one is made in hard-wearing but lightweight titanium.
There are two high-pressure ports either side of the main body of the regulator.
Four medium-pressure ports are arranged conveniently around a swivelling turret, while
a fifth allows a hose take-off from the end of the turret.
I find the first stage quite tall, and prefer to fit it to my tank with the turret facing downwards.

Second Stage
The business end of the regulator is an upgraded and remodelled design, but it has all the usual features that S600 regulator users will find familiar.
There is the pre-dive/dive switch that swivels the end of the second-stage valve to interrupt the clean passage of air that would otherwise benefit from a venturi effect. This avoids exponential freeflows at or near the surface.
There is also a breathing resistance adjustment (BRA) knob that allows the user to turn up the cracking pressure required to heave open the valve on each inhalation.
The purge control is easy to find and is progressive in its effect.

In The Water
Mouthpiece gripe apart, I used the S600 three times a day for a week and never had any doubts about its ability to deliver air at whichever depth I chose to go with it.
The regulator gave a dry breathe at absolutely any angle, and as an underwater photographer I can assure you that I tested it at most angles possible.

Atomic T2X, £1067

PRICE £1199
FIRST STAGE Piston-type
PORTS 5mp, 2hp
SECOND STAGE BRA and Dive/Predive Weight8920g
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