A year on from its official launch at the world's leading diving trade fair DEMA '96, a new Nitrox production system which is claimed to be cleaner, safer and easier to use has had significant success around the world. Dive boats and liveaboards operating in more remote diving areas have been particularly quick to take it up. Now the system, marketed as 'Hassle-free' Nitrox by designers and manufacturers Undersea Breathing Systems of Florida, US, is being made available on the European market.

It is based on the use of Enriched Air Nitrox or EANx, a relatively new concept in the sport diving context, but first mixed by English chemist Joseph Priestly as far back as 1773. It was then then put into use as a medical procedure, but subsequently was brought into play as a dive gas for commercial diving and, much later, for sport diving. Yet it has always provoked controversy, particularly on safety grounds.

A great pioneer in its use, and one of the figures behind the new system, is Dick Rutkowski, who retired from the US's NOAA in 1985 as its diving coordinator. Rutkowski, known as 'the father of Nitrox', was the driving force behind developing the training standards to use Nitrox in the private sector, and linked up with fellow American Bill Delp, founder of Undersea Breathing Systems, to produce the new system. Basically, Delp came up with a design to incorporate Rutkowski's process called 'continuous flow blending', a method of producing Nitrox in larger quantities 'in a more user-friendly way'.

Nitrox, an oxygen-enhanced mix of gas, enables divers to stay down longer with less decompression time. Delp explains: 'Up until the early Eighties, Nitrox was really produced by putting so many pounds of oxygen in a tank and putting air on top of that - called partial pressure blending.' Mathematical formulas and mix tables enable a trained blender to achieve the desired mix of oxygen and nitrogen. To reduce risk of fire or explosion, all components that come into contact with 100 per cent oxygen must be cleaned of combustible hydrocarbons and be made of oxygen-compatible materials. 'It is,' says Delp, 'inherently dangerous because you are handling pure oxygen, and it is really a small volume process. Yet it takes an awful lot of effort to produce such a small volume and to do it safely. 'We developed certain standards in mixing and blending to produce Nitrox very safely and in limited quantities.'

The process Delp and Rutkowski came up with still involved using pure oxygen, but meant injecting it into an air stream and then compressing that culmination of gases and pumping it directly into a tank. This meant it was produced more efficiently - but they were still handling O2.

'In the industry, they call it 'the folks who do the home brew', says Delp. 'There have been major fires. We have managed to avoid problems like that - we do a good job of oxygen cleaning!'

But the pair found that even with the continuous flow process 'There were too many risks to transfer it to a local dive store where the staff could make it safely.'

After studying a variety of different options to get around this, Delp came up with the idea of taking the nitrogen out of the mix rather than just enhancing the oxygen.

He explains: 'Any time you make Nitrox out of air you are changing relative ratio of oxygen to nitrogen. For example, if you wanted a 50/50 Nitrox blend, you have 21 per cent oxygen in air and 78 per cent nitrogen in air. Our process would allow us to take 57 per cent of that nitrogen out, which would give us a 50/50 mix. And if you didn't want to handle the oxygen at all, you had to use the oxygen that was already in the air and take the nitrogen out. We had to find technologies that would allow us to do that.' They did, spending three years developing their system.

Delp's machine then had to be refined. 'My ego got in the way', says Delp, 50. He started diving at 17, became an instructor but never taught; and worked as a hyperbaric technician, and for the US government in different capacities; and as an engineer almost exclusively in design and development for life support systems and high altitude reconnaissance aircraft.

'Engineers like to put on all sorts of bells and whistles to make something look technical. We put our original model into dive stores, but people were completely confused with what buttons to press. And it was expensive. Once we found it was working, I had to redesign it to make it applicable in the real world.' Now his machine is down to two valves, weighs around 70lbs and costs around $20,000.

An investment indeed, but one of the major selling points, apart from its proclaimed safety (and top operators such as Peter Hughes, and the Aggressor Fleet have already taken it on) is that the system involves very little maintenance and has a life of around 30 years, according to Delp.

'There is one filter in the little black canister at the top that has to be changed four times a year. It takes about five minutes to change, which the dive store owner would do, and costs about $40.'

From February until the end of December last year, Delp says, the company sold more than one million cubic feet, or 28 million litres, of Nitrox.

'That's how easy this system is to work,' says Delp. 'I had it fully automated so you push an 'on' button for go and a red 'off' stop. You tell it what concentration you want with a computer pad ... and you go to lunch. Then I replaced the electronics with mechanical functions, which are actually cheaper and more reliable.'

The system does, he says, require a little more space for the pressures and equipment. 'The old way was one tank at a time. This machine is capable of producing 20 cubic feet of gas a minute, approximately 450 litres. So you could fill a 12 litre tank in a minute. To do that safely with partial pressure, the system generally in use, would take 20 minutes. And there's the risk to the person.'

'Our interest in the long run', says Delp, 'is supporting the rebreather industry. For a rebreather to be cost-effective it will have to be a semi-closed system for the recreational market and it will have to be Nitrox-based as a primary breathing gas.'

Vincent Schutte of Nitrox Holland, the system's agent and supplier for Europe, says he believes divers still don't fully understand the the benefits of Nitrox. 'It has been seen as too technical -- too dangerous to use successfully and too complicated to use as a diver. With our system there is nothing else for divers to worry about except proper labelling on the tank to show the air in it has a higher oxygen level.'