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| Don't judge a reg by its mouthpiece--it's the easiest and cheapest thing to replace.|
Shopping for a new regulator is serious business with a sizable price tag, so you want to do it right. You've probably read through the catalogs, checked the ads and visited the web sites of the various manufacturers. And you're probably still confused. For example, do you want a piston or a diaphragm design? Balanced or unbalanced first stage, or second stage, or both? Diver adjustments? Environmental seals? Titanium? Alloy? Technopolymer? And how does a $160 budget model stack up against a luxury one costing almost $1,600?

• Number of ports: One or two high-pressure ports, with four or five low-pressure ports, is the norm. More ports is always better because one or two may be difficult to use without bending a hose too much.

• Arrangement of ports: Some radiate in all directions around a central axis, some have groups of two or three leading off in the same direction. Which works best for you depends on your particular setup.

• First stage swivel: This usually gives you more ways to route the hoses, or lets the crowd of hoses find its most comfortable orientation.

• Right-angle first stage: That's the design where the yoke is at right angles to the body of the first stage. Most people mount it with the reg below the yoke, but you can mount it upside down and raise all the hoses five or six inches if that works better for you.

Let Rodale's Scuba Diving guide you through the thicket of engineering lingo and brochure "happy talk." At the end of the trail is a reg within your budget, no matter how large or small, that will do the job. First, some priorities:

Priority One: Life Support.

Your regulator has one job--to deliver lots of air, at any depth and with a low work of breathing. So skip straight to the bottom line: the actual performance of the regs on impartial, objective breathing simulator tests. In next month's issue of RSD, a special Scuba Lab review of 69 current regulator models--ranging in price from $160 to $1,596--will include the breathing machine scores, and some of the results are pretty surprising.

How a regulator goes about delivering air--pistons or diaphragms, balanced or unbalanced first stages, adjustable or nonadjustable second stages--isn't as important today as it was 10 years ago. Credit clever engineers or blame clever lawyers, but today no company can afford to sell an underperforming regulator. Nearly all of them--regardless of price or design--will safely deliver all the air you'll need down to 130 feet and a good distance beyond. There are many regulators priced well under $300 that do the basic job and even some budget models that deliver as much air in extreme conditions as the most expensive ones.

Priority Two: Comfort.

Of course, breathing machine performance isn't everything. Some regs that score well on the machine also have annoying habits. They may honk or buzz when you suck on them. They may push more air at you than you want, something called "positive pressure breathing," or they may freeflow readily on the surface. They may breathe wet. And some may breathe well in the normal swimming position but less well when you get upside down. Overcoming these problems requires more time and money refining the design, and may involve some of those highly promoted features, so expect to pay more.

To find out how well a reg performs, you really have to dive with it. If you can, borrow or rent as many regs as you can and dive them. Try them in all possible swimming positions. Is the breathing smooth or erratic? Wet or dry? Is the second stage comfortable in your mouth? Is the hose long enough? Are the exhaust bubbles in your face? These are the same criteria Scuba Lab test divers use to evaluate regulators for human comfort, and their findings are also included in next month's report.

Priority Three: Convenience.

Can you hook up the reg to all your appliances, for example? Here the catalogs can actually help a little, and handling the thing itself in the store can help more. Before buying a reg, take your BC and console to the shop and set everything up on a tank. Play with hose routings and swap for longer or shorter hoses if necessary until you and the hoses are all comfortable. Consider:

Again, you may pay more for these options, but if they're important to your gear configuration, it's probably money well-spent.

Priority Four: Style and Status.

Do you ache for the latest and greatest? Do you fly first-class all the way? Is the Commando XL 10,000 SuperReg carved from beryllium and platinum calling your name?

We're talking about status and self-expression now, and you know what stokes your fire better than we do. And if you can afford a high-end model, go for it with a clear conscience because the rest of it--the function, comfort and convenience--will be there, too.

The Bottom Line

So we're back at the beginning. How do you choose a regulator? Think of it this way: Buying a scuba regulator is a lot like buying a car. Just about any basic model will do the primary job--get you there and back in reasonable safety--but moving up the price ladder generally buys you more performance, comfort, features and style. It's a matter of selecting the combination that best suits you within your price range.

But there's another similarity between buying a regulator and buying a car--both require dealer prep and regular maintenance to perform properly, so the quality of the dealer may be as important as the quality of the product.

Shop for a dive store as diligently as you shop for the actual regulator. Find a dealer you like. He or she should spend time on you cheerfully and respectfully as you make your choice. The store should stock at least two major-brand lines of regs and be able to service, on site, what it sells. It should not only offer dealer prep, it should insist upon it.

Decide how much you want to spend, and choose something in your price range from that store--even if a marginally "better" reg is available from mail order or from a store you don't like as well. Why? Because your reg will require annual tune-ups to stay in peak condition and to preserve your warranty rights. Plus there's the added bonus that "your" store is more likely to go the extra mile to make sure maintenance gets done right and on time--even when you need an overhaul right before that dream trip to the tropics.

How it works: Piston vs. diaphragm first stage

Until regulators incorporate computer chips (which may not be so far off), something inside the first stage has to move back and forth to physically open and close the valve that admits air from the tank. That "something" is a piston sliding in a smooth cylinder or a membrane (like a loose drum head) that flexes back and forth.

In both cases, atmospheric pressure and a spring push against one side of the piston or diaphragm to open the valve, and air pressure in an "intermediate chamber" pushes on the other side to close the valve. That intermediate chamber connects directly to the hose and the second stage.

When you open the tank valve, high-pressure air fills the intermediate chamber until its pressure is high enough to overcome the spring plus ambient pressure (air on the surface, water after you submerge). Then the piston or diaphragm moves and the valve closes.

When you breathe, you draw air from the intermediate chamber, the pressure there drops, and spring plus water pressure now push the piston or diaphragm to the open position, letting air into the intermediate chamber until it again equalizes and closes the valve.

So which is better--piston or diaphragm? In theory, each has advantages and disadvantages, but in reality, there is little or no practical difference in performance.

What About Titanium?

This wonder metal shows up in high-end regulators, Rolexes and golf clubs--anywhere, in fact, a customer slaps down a platinum credit card.

Titanium has enormous prestige value, but does it do anything for the performance of a regulator? Yes, a bit. Here are the claims usually made for titanium regulators, and the facts:

CLAIM: Titanium is virtually impervious to saltwater corrosion.
FACT: It's true. But this is mostly a solution in search of a problem. Chrome-plated brass, the traditional material for first stages, is nearly impervious to corrosion too, assuming you rinse it in fresh water and keep water out of the inside.

CLAIM: Titanium is lighter than brass.
FACT: It's true. But this applies to the first stage only. If you travel and pack your reg in carry-on luggage, you will be glad titanium weighs a pound or so less. On the other hand, you might be willing to pack a cheaper brass reg in checked luggage.

CLAIM: Titanium is nontoxic.
FACT: It's true. Don't try to eat a brass regulator. What about breathing air that has passed through a brass regulator? It has already passed through much worse stuff in the compressor and sat for a long time in an aluminum or steel tank. Worry about that if anything. (Check your first stage filter for discoloration.)

CLAIM: Titanium is stronger than brass.
FACT: It's true, pound for pound. But brass regs do not fracture or burst open. Another solution in search of a problem.

CLAIM: Titanium is the choice material of the "serious" diver.
FACT: Better define "serious." Titanium is not recommended for nitrox blends richer than 40 percent--those deco blends tech divers use, for example. At least one manufacturer warns against using a titanium reg with any nitrox blend. It's because titanium is a little more flammable than brass. Is flammability a serious problem? No, manufacturers (and their lawyers) are just being cautious.

What About Adjustments?

There are two types of adjustments, both found on the second stage. One is a pre-dive/dive switch, meant to prevent freeflows on the surface. It's usually a two-position switch (though it doesn't turn the air all the way off) and it's often mounted on the top of the reg close to the mouthpiece.

The other is a fine-tuning adjustment meant to prevent positive pressure breathing. This one is usually a rotating knob on the side.

Some regs have one adjustment, some have the other, some have both and some have neither. Advertising copywriters just love those adjustments but don't seem to understand them very well, because they've invented all kinds of confusing names and explanations for them. Like "a pre-dive/dive switch allowing for the fine-tuning of the reg ..."

Engineers apparently aren't as devoted to them because often they haven't marked the switches and knobs clearly, so it can be hard to tell which way to turn them. Often it doesn't much matter anyway.

Dials are sometimes useful on regs with very low work of breathing, because they are naturally close to positive pressure. Swimming hard or into a current can sometimes fool these second stages into giving you more air than you want unless you detune it. In normal conditions, the adjustment should be kept in the fully open position.

More often, adjustment knobs are added to lower-performance regulators because, well, catalog writers just love those knobs.

Balanced or Unbalanced?

Balancing is an attempt to keep air delivery stable when tank pressures are low or demand on the regulator is high--when you're deep and breathing hard or sharing air, for instance. Compared to older, unbalanced models, balanced first stages do breathe more consistently regardless of tank pressure or demand. However, it's now possible to make unbalanced first stages with breathing performance very similar to balanced ones.

In recent years, a similar concept has been applied to second stages, so that incoming air (from the hose) does not alter the behavior of the valve. There is less scope for improvement here, however. Balancing the second stage can make the air flow slightly "smoother," more consistent, though the difference is subtle.

What About Environmental Sealing?

The idea is to keep water out of the first stage workings while still allowing the reg to sense the water pressure. It's not a bad idea, but unless you're diving in cold or polluted water, it's really not necessary.

Cold water (below 50F, say) can be chilled further by the decompression of air entering the first stage from the tank, causing icing, which can jam the mechanism. Pollution can cause, well, who knows what harm to the reg, but nobody likes it.

Our advice: If you dive in anything like a freezing sewer, spring for a sealed first stage by all means. If you dive in clear tropical water, don't worry about it.