EVERY REGULATOR MANUFACTURER CAN SUPPLY a graph to show what a superb performer each of its products is. This information can be useful - but only when applied to specific cases.
     We divers are not machines, but emotional, psychologically complex animals. That's why, in the late '80s, Diver pioneered side-by-side comparisons of regulator performance, using not just breathing machines but human divers at depth.
     A proper underwater regulator test that is anything more than superficial is quite an undertaking. The test-divers eat, breathe and sleep regulators for a week, and during that time they have to get to know all the models tested extremely well. A quick dip in the briny is not good enough. They have to dive and dive and dive again.
     Each diver will spend up to 13 hours under water to try 13 regulators. The water has to be sufficiently deep, and the conditions consistent and reliably good. If there are any delays due to weather constraints, for example, impressions get confused and it means starting back at the beginning.
     We need to get a fair and impartial impression with plenty of time spent in the water but in the shortest possible time-frame.
     Some critics have suggested that we should do the tests in British waters. Unfortunately, only rarely could home conditions meet our requirements, or our budget for that matter.
     Apart from the aspect of free-flow due to freezing, a phenomenon that rarely occurs in the sea, water temperature seems to make very little difference to the regulators - only to the ability of the test-divers to discern a difference!
     It is also impossible to know how close a regulator comes to freezing until it's too late, so definitive tests are not really possible. It appears to us that almost any regulator can get a EN250 Cold Water certification if the manufacturer is prepared to pay the cost, and it also appears that almost any regulator can malfunction due to freezing if the conditions are right and the user allows it to happen.
     So rather than try to unravel incomprehensible results from divers who are uncomfortable and possibly narked because of poor visibility, strong currents and cold conditions, and whose diving pattern is always in danger of being disrupted by bad weather, we reckon it's far more efficient to go to the nearest area of sea that gives us consistent and benign conditions.
     That's why we always seem to do these tests in some part of the Gulf of Aqaba. As with our test of regulators retailing for less than £150 (April, 2001, www.divernet.com/equipment/0401 regtest.htm), for this test of mid-price regulators Emperor Divers and the Coral Hilton Hotel helped us to set up in Nuweiba, Egypt.
     Selecting the right panel of testers is also important. We try to choose a range of people representative of diving types, but with, as far as possible, open minds. That can be difficult. They also need to be competent enough to do the job (see panel).
     My task was to oversee the operation and ensure that it was carried out to the continuing high standards that Diver has set.

The in-water tests
     As before, each diver acted as part of a buddy team. Each wore independent twin cylinders mounted on a Buddy Tek Wing jacket equipped with twinning-bands and blocks. So each buddy team had four cylinders between them, each cylinder fitted with a different test regulator, each regulator with two second stages.
     This meant that not only could a pair compare four different regulators at one time but they could also check whether there were any differences in performance at depth with two people breathing at the same time from a single regulator first stage, as might happen when an octopus rig is used.
     Each dive was mirrored by the next. We went to a depth exceeding 40m, accessed by way of a long swim out from the shore and dropping down to the site of an old ship's mooring from the days of the Israeli occupation of the Sinai.
     A depth of 40m was easily found within sight of the mooring's sinker-blocks. A swim along back up the reef provided a convenient way to stage decompression and gave the test panel more time with the regulators.
     Of course, all the regulators tested worked. No-one drowned! You would expect that, and we were not expecting any such problems with regulators in this price range.
     What we were looking for were the sometimes subtle differences between the competing products.

Inversion
Most regulators tend to give a little water when inverted, because the exhaust port is positioned above the rest of the second stage. Some, however, are wetter than others.
     Why is this relevant? In an emergency someone in a hurry might stuff an unfamiliar regulator into their mouth inverted. Or, when descending headfirst at speed, the regulator might become inverted - or you might have need to look directly upwards during a dive.
     On two occasions during photo-shoots for this feature we needed someone to lie on the sand and look straight up. Each time we were able to choose the most suitable regulators from the selection available. Some of them were very unsuitable!

The ANSTI test
Once the human tests were done, we sent the regulators, now no longer shiny and new, to ANSTI Test Systems, to see what the breathing machine thought of them.
     The tests were done with 50 bar supply pressure at around 50m (where all the regulators performed adequately) with a ventilation rate of 25 breath-cycles and 63 to 64 litres per minute. ANSTI tests are done head-up without a mouthpiece in place.
     The print-out of the breathing cycle is read clockwise starting from the right. It reveals the effort needed to crack open the valve, followed by the effort of inhalation and then the exhalation effort passing back over the top of the horizontal axis of the graph.
     We looked for a nice clean oval shape with as little total effort (represented by the interior volume of the oval) as possible.

The regulators
We allowed regulator manufacturers/distributors to nominate one model each for the test.
     All the first stages had four medium-pressure and two high-pressure ports, with the exception of the Scubapro, which has an additional mp port at the top of its turret. Some had over-sized ports for the primary second stage.
     Those regulators with ports set around a fixed barrel usually gave less comfortable hose routeings, whereas those with turrets that were tall invariably needed to be inverted on the tank, so losing the ability to rotate fully if they were not to clout the diver behind the head. Squat turrets gave the best hose routeings.
     Some regulators had breathing adjustment (BRA) knobs to their second stages, designed to adjust the effort needed to "crack open" the valve with each breath. Others had venturi ± switches (dive/pre-dive) designed to discourage exponential free-flows at the surface. Some had both, while others had or needed neither of these devices.
     We checked how easy it was to strip and re-assemble each second stage for cleaning. This can be important if you get sand or grit inside during shore-diving or in turbid water.

Conclusion
     By the end of the week it was time for a leisure dive. Our testers had a choice of any of the test regulators, and four emerged as clear favourites - the Apeks and the Aqua-lung, the Tusa (a surprise newcomer to the UK market) and the Mares. That quartet was closely followed by the Oceanic and Scubapro models.
     It was no surprise to find that the regulators considered best were among the more expensive, though the test divers were largely unaware of the specific prices at the time of the test. The regulators are presented in ascending order of price.

"What did you think of...?" The test team from left is Andy Diez, Louise Trewavas, Martin Skelly and Jan Ellingsen.


Martin and Jan compare notes


Typical scene on the seabed as the two buddy-teams try out the regulators at about 40m.

ANDY DIEZ, originally from Mainz in Germany, is 35, a PADI IDC Staff Instructor and manager of Emperor Divers in Nuweiba. He has been diving for 10 years and professionally for six. With his partner Steffi he has worked at dive centres in Sicily, Kenya and Egypt.
MARTIN SKELLY was, at 32, the baby of the group. Originally from Liverpool, he is now an IT consultant from Redhill, Surrey, with his own business. A PADI Advanced Diver, he has been diving extensively for seven years in places as different as Cocos Island and the Red Sea.
JAN ELLINGSEN is originally from Norway and a former commercial diver. He is 41. Jan has skippered several well-known liveaboard dive vessels in the Red Sea, including Colona 2, Colona 4, Manta Ray and Poseidon's Quest. He now owns two sea-going tugs operating in the Solent and lives in Sussex with his wife and children.
LOUISE TREWAVAS is Editor of Dive Girl magazine and of the Divernet website. She is a technical diver and committed closed-circuit rebreather enthusiast but, once persuaded to use open-circuit for this exercise, we knew that she could be relied on to come up with some entertaining and pithy opinions.