SCUBALAB TESTS: REGULATORS 2009

On a sun-splashed Southern California morning last April the ScubaLab test team, aboard Body Glove’s dive boat Disappearance, skirted the eastern coastline of Santa Monica Bay, headed for the rocky cliffs of the Palos Verdes Peninsula. Skipper Bob Meistrell eased his 64-foot vessel into a quiet spot on the edge of a massive kelp bed and dropped anchor on a sandy bottom in 40 feet of green water. The test team, comprised of six divers and one test coordinator, got ready to hit the water with this year’s new crop of regulators. There were 14 in all, running the gamut from economy to money’s-no-object. This was judgment day — the final of three test stages — and we couldn’t have asked for a better one. When all was said and done, we found what we were looking for — the year’s best breathers.

|July 2009 Issue Scuba Lab Review Quick Links| |---| |$500 and Over| |---| |Atomic Aquatics T2x| Atomic Aquatics Z2x| |HollisGear DC3/212| Mares Abyss 22 Extreme| |Mares Carbon 42| Oceanic Delta 4.1| |SCUBAPRO Mk25/A700| | |$500 and Less| |---| |Aqua Lung Titan LX| Cressi-sub Ellipse Ti/MC-9| |HoliisGear DC4/221| Mares Prestige 12S| |Oceanic Neo| Tilos RS811/OCFR-02| |Tusa RS-670| |

Test Procedures

Before diving in the real world, all test regulators endured long hours in the ScubaLab workshop undergoing extensive poking and prodding under pressure to make sure all systems were “go.” Staffers poured over owners’ manuals, studied literature and conducted Internet searches to dig up as much info as possible on each breather. All the while, copious notes were taken on all aspects of each reg in a “dry” test environment. Then it was off to an R&D lab where the regs spent two days hooked to an ANSTI breathing simulator. There, following a surface check, each regulator was tested at three different breathing rates, known as RMVs (respiratory minute volumes, basically the amount of gas that can be ventilated through the lungs in one minute), at three depths, for a total of four RMV/depth combinations. In all, 560 data points were collected documenting how hard — or easy — a time the regs were having breathing at each test level. These data points were supported by more than 80 pages of breathing “loops,” a graphic representation of a regulator’s inhalation and exhalation performance. For the in-water phase, experienced test divers got a chance to use these regs like they were designed to be used. Armed with underwater slates, divers rated each reg in seven specific ergonomic categories, ranging from the most important (ease of breathing in all positions and dryness) to moderately important (ease of purging and bubble interference) to convenience items (comfort and adjustments). The reviews that follow are based on these test results. For full details on each test phase, along with detailed charts and bonus material, log onto scubadiving.com.

Defining Simulator Breathing Rates

For ScubaLab tests, following a surface check, each regulator is tested at three different breathing rates, known as RMVs (respiratory minute volumes, basically the amount of gas that can be ventilated through the lungs in one minute), at three depths, for a total of four RMV/depth combinations. These breathing rates were chosen to enable us to 1) simulate a recreational diver’s breathing rate, 2) conform to recognized industry testing parameters for purposes of comparison, and 3) surpass normal breathing rates to determine reserve capacity. Following are the four RMV/depth combinations that ScubaLab uses to test regulators, what they represent and how you can apply them to real-world diving situations. 37.5 RMV @ 132 FEET This test point is the one that most closely represents typical recreational diving. The depth, 132 feet, is the maximum depth recommended for recreational divers, and the 37.5 RMV breathing rater is very close to how a physically fit recreational diver might breathe while swimming a long distance (for comparison, a relaxed diver doing a drift dive or taking photographs will be breathing at about 22 RMV or less). A fit diver could theoretically maintain 37.5 RMV for five minutes or longer without becoming significantly winded. From an engineering standpoint, this rate also gives a good view of the smoothness or lack of smoothness of a regulator’s demand valve, and it shows a consistency curve when compared with higher RMVs. 75 RMV @ 132 FEET Only the U.S. Navy and ScubaLab use this breathing rate to identify equipment potential or limitation. This is considered an “extremely” heavy-work breathing rate. A diver in excellent condition can breathe at 75 RMV for only about a minute. Beyond determining a regulator’s reserve capacity in high-stress conditions, this rate also provides a pretty good indication if a regulator is capable of supporting two divers at the maximum recreational depth while buddy breathing (75 RMV divided by two equals 37.5 RMV). While this is not scientific, it offers a reasonable amount of assurance that the regulator can accomplish the goal easily, with difficulty or not at all. 62.5 RMV @ 165 FEET This is the standard test depth and “high work rate” used by the European conformance standard EN250 for evaluating regulator performance, which currently is the world’s dominant testing authority on regulator performance. Consequently, it is the test point of highest interest among regulator manufacturers. Considered to represent “heavy work,” a recreational diver in excellent condition aggressively chasing a huge bat ray through open water would be able to maintain 62.5 RMV for only two or three minutes. 62.5 RMV @ 198 FEET This is the U.S. Navy’s Class A test depth and breathing rate (although the Navy uses a higher-supply pressure in their reg testing). This is a test point designed to stress a regulator to find the outer limits of its reserve capacity. Obviously, no diver in his right mind would ever be breathing so aggressively at such an extreme depth with so little gas in his tank. This is for the lab-coat crowd only. Tests are performed at a HP supply pressure of 725-760 psi to conform to EN250 test standards. This low supply exerts additional stress on the regulators. Tests have shown if a regulator can perform well at this lower-supply pressure, it will perform as well or better at higher-supply pressures. Note: Simulator tests are not intended to pass or fail regulators, but rather to scientifically gauge their performance based on controlled conditions. What’s more, breathing-machine performance does not necessarily reflect in-water performance, simply because there are too many real-world variables that simulators can’t measure. A machine might be able to tell you how hard or easy a regulator works to deliver gas at certain depths and breathing rates, but it can’t tell you about a regulator that stutters or whistles, or a purge so stiff that clearing is difficult, or whether a regulator will choke you with water when you go heads-down at 50 feet. So while breathing-simulator results are important, they represent only half the story. To capture the complete picture, you need to consider both breathing-machine performance and ergonomic in-water performance.

|July 2009 Issue Scuba Lab Review Quick Links| |---| |$500 and Over| |---| |Atomic Aquatics T2x| Atomic Aquatics Z2x| |HollisGear DC3/212| Mares Abyss 22 Extreme| |Mares Carbon 42| Oceanic Delta 4.1| |SCUBAPRO Mk25/A700| | |$500 and Less| |---| |Aqua Lung Titan LX| Cressi-sub Ellipse Ti/MC-9| |HoliisGear DC4/221| Mares Prestige 12S| |Oceanic Neo| Tilos RS811/OCFR-02| |Tusa RS-670| |