TESTCENTRE
Untangling regulator jargon
All too often , the decisions in buying a regulator are shrouded in opaque terminology . Neil Hope pulls the veil back to reveal a consumers ' guide to modern regulators and their features
While the basic principles behind Jacques Cousteau and Emile Gagnan ’ s original 1940 ’ s aqualung remain the same , the ensuing years have brought vast improvements in design , with lighter and more durable materials , increased performance and reliability . As Test Centre often refers to a variety of different features that are part and parcel of the modern-day regulator , we decided to take a look at some of the common terminology used by manufacturers – and what they mean to potential buyers .
First Stages
First stages as we all know , convert our high cylinder pressure ( 232-300bar ) down to around 8-10bar via an interstage hose , which allows us to breathe at ambient pressure at the second stage . As the diver breathes in , the valve opens and gas flows into the mouthpiece . When breathing out , the valve closes as the exhaled gas is vented .
Commonly manufactured from chromeplated brass or lightweight and corrosionresistant titanium , first stages house a number of medium / low and high pressure ports . These outlets enable connection of primary and alternative second stages , drysuit and BCD inflation hoses plus contents gauges / wireless transmitters .
60
Yoke v DIN
The Yoke or A-Clamp fitting has been around since the earliest days of diving . Pressure-rated to 232 bar , its A-shaped frame slips over the cylinder ’ s valve and is tightened up against an o-ring via a large knob . In the UK and Europe , they are largely being superseded by the increasinglypopular 300 bar DIN fitting .
DIN ( Deutsche Industrie Norm ) fittings feature a threaded male fitting , which screws much more securely into the cylinder valve itself . In addition to their increased capacity ( 300 bar v 232 bar ), the smaller DIN first stage can also offer weight advantages versus its Yoke counterpart .
Although adapters are available both ways ( Yoke to DIN and vice versa ), do bear in mind that while a 300 bar DIN regulator can be used with a 232 cylinder valve , a 232 bar regulator is only compatible with a 232 bar cylinder .
Piston v Diaphragm
Regulators are available in two basic designs : piston and diaphragm . The former relies on a moving piston and spring to reduce high pressure to low . The latter uses a flexible diaphragm pushing against a poppet assembly to do a similar task .
Piston first stages are the simplest design , with what amounts to a single moving part – their wide bore stem produces a high volume gas flow . They can be found on both entry-level and flagship models .
The diaphragm regulator is more complex in design , with a smaller bore valve giving a slightly reduced performance in comparison . However , the internal components are completely enclosed and therefore protected from contact with water , contamination or detritus . This is a positive for cold water use , where the potential for free-flow is decreased .
Environmental sealing
For diving around our chilly UK coastline and even chillier inland sites , an environmentallysealed first stage is an essential preventative measure to avert the build-up of ice crystals on internal components . This can lead to a potentially-catastrophic loss of gas due to free-flow .
This type of seal employs a silicone or alcohol-based fluid in order to produce a watertight barrier . Hydrostatic pressure can still be transmitted to the valve and the process is suitable for both piston and diaphragm first stages .
Another method to help prevent free-flow is by the use of heat exchange fins . These help to increase the surface area of the first / second stages , and dissipate the cold by extracting warmth from the water around it . The current European standard for cold water regulators is EN250A and can be found stamped on the first stage of compliant regulators . This ensures that both the primary second stage and its alternative air source are tested to a minimum of 30 metres , and suitable for temperatures less than 10 ° C / 50 ° F .
Yoke and DIN first stage fittings side-by-side