Learn more about this vital piece of equipment that helps you breath underwater.

Scuba diving regulators

Find out how to select the right regulator


Simply put, a scuba regulator is the device that delivers air to the diver and lets the diver breathe underwater. All regulators sold in professional dive centers today are reliable, and many have fantastic added features that make diving easier and more fun.

Regulators deliver air to the diver by using two separate “stages” to reduce the high pressure of the air from the tank. Both stages working together make it possible for the diver to get air delivered at a pressure that is comfortable for breathing.  Most modern regulators are of a “single hose” design, so-called because a single hose is used to move air from the scuba tank to the diver’s mouth, allowing them to breathe easily. The air moves first through a regulator first stage which is attached to the scuba tank, into the regulator’s second stage, which is the part through which the diver breathes. The second stage has a comfortable mouthpiece attached allowing the diver to breathe from it easily.

If you look at them in cutaway drawings regulators may seem technical and complicated, but all modern first and second stages are actually very sound and straightforward devices, specifically designed to be tough and trustworthy.

How a Regulator Works

regulators diagramHere’s how the basic regulator works: When you breathe in on the second stage, you create a drop in pressure inside the body of the second stage. This causes a specially-designed silicone rubber diaphragm to move inward (sort of like when you inhale on a plastic soda bottle and the sides move inward). The diaphragm contacts a lever attached to a small valve which rocks open, allowing air to enter the mouthpiece. If you only breathe in a little, the diaphragm only moves a little, and just a little air is released. But if you inhale forcefully, the diaphragm and lever move farther, giving you a larger volume of air. As the air in the hose feeding the second stage is at an “intermediate pressure” of around 140 pounds per square inch (PSI), the amount of reserve air available is still formidable: with some regulators you can “purge” the second stage by pushing in on the diaphragm and ruffle somebody’s hair across the room! So suffice it to say that the air available at any one time will be greater than what you could ever use in a typical diving situation.

The first stage, which is located between the scuba tank valve and the hose feeding the second stage, is responsible for taking the high-pressure air coming out of the tank and reducing it to the 140 PSI or so intermediate pressure that the second stage needs to function properly.

One thing all modern regulators have in common is dependability. They are built to stringent quality standards and they are designed in such a way as to always provide air to the diver, as long as there is air in the scuba tank. Even if there is a problem with the regulator underwater due to lack of yearly maintenance, the regulator will still deliver air to the diver, though it may “freeflow,” and use up the air in the tank quickly.

Which One is Best

Modern regulators come in a wide variety of shapes, sizes, materials, and technologies, as well as a wide range of prices. If you’ve never shopped for a regulator before, you’ll find there are many choices available. Your professional dive retailer and your professional instructor can help you understand the different features and benefits of the various models and styles. A great way to start is to look to the type of regulator your instructor uses. An instructor’s regulator (and their other equipment) is usually top quality and they choose their regulator because it needs to work properly over the course of many dives.

If you are going to do primarily the sort of diving that the typical newly certified divers usually enjoys – relaxing dives on vacation in warm-water locations, and at recreational depths – you’ll do fine with literally any regulator on the market today. If it’s sold in your local dive center, it will be a high-quality piece of gear that will serve you well for vacation diving for many, many years to come.

So why are there so many different regulators on the market? Generally the variety is there to answer needs generated by specific and specialized types of diving.

If you’re planning on traveling a lot, for instance, and you need to conserve weight and space in your baggage, it will probably interest you to know that many manufacturers offer regulators for the traveling diver that are both lighter in weight than, and pack more compactly than, your average regulator. These light weight regulators may, for instance, replace the marine-grade plated brass used in many regulator components with strong, lighter-weight alternatives, such as titanium.

But the vast majority of premium regulators are designed to handle one or more of three conditions. They are designed to be used in colder water, or they are made to be used comfortably at greater depths, or they are designed to function well under high workloads – swimming against a strong current, say, or doing something strenuous like dislodging a stuck anchor or digging as part of a scientific underwater archaeology project. To understand how these high-performance regulators work, you can look at differences in their basic design.

Types of Regulators

It’s important to know that, when it comes to performance, some of the most significant differences in regulator design are found in the first stage.

You’ll hear most first stages being referred to as unbalanced or balanced, and as piston or diaphragm designs. Here’s what those terms mean:

  • Unbalanced means that the first stage uses tank pressure, in part, to open or “crack” its internal valving. This means that, as the air in the tank gets used up, the inhalation effort required to open the valve gets marginally higher. At shallower depths – say, less than 100 feet – and low workloads, the difference in inhalation effort is minimal so you might not even notice it. But at deeper depths encountered by advanced or technical divers, or under heavy workloads, such as swimming against a strong current, the difference might become noticeable.

  • Balanced first-stage designs “crack” or open without assistance from tank pressure, so ease of breathing remains constant throughout the dive. The design usually makes such valves a little more costly, but if you’re doing a lot of deep diving or working hard during your diving, the difference in cost is worth it, particularly if you think of the cost being spread out over hundreds of dives.

Water has weight, so there is more pressure pushing down on you and your gear as you do deeper (this is why you’ll hear about divers equalizing the pressure in their ears – so called “clearing” – and equalizing their masks – they are putting more air into those spaces to compensate for the higher pressure caused by the water). To work properly, the first stage must have a way of “sensing” this pressure, and that’s where “piston-” and “diaphragm-” type first stages come into play.

  • Piston-type first stages work by allowing water to enter the first stage and press directly on a piston within a sleeve – the greater the depth, the higher the pressure, and the greater the pressure applied directly to the piston mechanism. Because there is only one moving part, this is a great and extremely durable design under most underwater conditions, which is why you’ll see so many regulators with “balanced piston” as part of their specs. Piston regulators do have certain disadvantages in extremely cold (freezing) conditions or in very dirty water, but since most recreational diving takes place in clear water which is above freezing, these disadvantages are minimal. Manufacturers of piston regulators offer “environmental seal” kits that encapsulate the piston in a flexible boot that is filled with a clean and freeze-resistant material (such as inert silicone), allowing the pressure to be transmitted to the mechanism just like water pressure, while keeping it separated from the cold or dirty water. An alternative is to go to another first-stage design …

  • Diaphragm-type first stages have two parts to their valve-opening mechanism: a lever within an air space, and a diaphragm that presses in as that air space contracts from increasing external pressure. This design does not allow water to make direct contact with the internal mechanism of the first stage, making this a design that works well in dirty or very cold water – the sorts of conditions routinely encountered by ice divers and rescue divers. Because the diaphragm design allows no direct contact between the first stage mechanism and the water, these first stage designs are often used in diving classes where there is likely to be less care used in handling the regulator.

Second stages can also be of a balanced or unbalanced (sometimes called “downstream”) design, and again, while downstream regulators are common in rental inventories and work great under most recreational diving conditions, the slightly greater investment to buy a balanced second stage can be money well spent if you do lots diving, or intend to take up specialty diving in which you may find easier breathing effort a desirable feature.

Octopuses and Safe Seconds

All divers carry a backup second stage, also known as an “octopus regulator” or a “safe second stage.” This regulator acts as a backup in the event that another diver needs additional air to get back to the surface, or more rarely in the event of a problem with the diver’s own second stage. The backup can either be a second mouthpiece attached via its own hose to the first stage, or incorporated into the hose that you use to inflate and deflate your buoyancy compensator.

As a general rule of thumb, your octopus should have performance characteristics similar to those of your primary second stage. That way, if you have to go to someone’s aid, they will be breathing from a regulator as good as the one they started the dive with – a good way to take some of the pressure out of a possibly stressful situation.

Some divers also consider the use of a second, independent (and smaller) air supply. This consists of a separate small tank and regulator system attached to the diver – sometimes attached to the diver’s primary tank. This system serves the same purpose of helping a fellow diver in need of air, but is completely independent of the diver’s own air supply.

When & How to Buy

Because it is such a key and central component of your dive-gear package, a good regulator is usually one of the first purchases you’ll want to make after getting the basic mask, fins and snorkel that you’ll need to participate in your certification class (also called open-water diver training). If you already know what sort of diving you’ll mainly be doing after you’re certified, you may want to buy a regulator and use it during your open-water classes – that way, your local professional dive retailer and your instructor can answer any questions you might have about your regulator.

Having your own regulator means you’ll have a central and pivotal piece of gear already sitting in your gear bag when an opportunity to dive comes up. If you own your own reg, you’re likely to dive much more often – and that’s where the fun is.

Regulator stages are often available separately, but not every second stage will work optimally with every first stage, so unless you know gear inside and out, it’s crucial that you have your dive center’s guidance when you purchase your regulator. They can help foresee things you may not think about – such as how to set up your regulator first stage so that it is most comfortable for you. They can also help guide you on the additional types of diving available in your local area, and make sure you choose a regulator that will work in a variety of diving conditions in which you may be interested.

The professionals on staff at your local dive center are experienced in considering contingencies such as this. Shopping with them will help you get the best use out of what you’ve budgeted for gear purchases.

Regulator Maintenance

After every day of diving, you should soak the regulator and its accessories in clean, fresh water. Soaking in warm water (say, in your hotel room bathtub while you are gone to dinner) is even better still. And “swish” the regulator in its fresh water bath before removing it and hanging it to dry. This helps rinse away grit and sand, and helps remove salt that can otherwise crystallize and impair regulator function.

As you add accessories, such as air-integrated computers, to your regulator, you’ll also want to inspect the O-rings and replace anything that looks cracked, chewed up or obviously worn. If you ask your dive center to install any accessories, their staff will check for worn components such as this on opened components as a matter of course, and they can also add some nice touches such as hose protectors (which protect hoses at the attachment point, where they are most apt to bend or wear).

Most importantly, the regulator should be inspected and serviced at the interval recommended by the manufacturer (usually annually) to be sure it is ready for the diving season. In fact, many divers have their regulator inspected and serviced at the end of the diving season, putting it away in a clean and serviced condition when the diving season has ended for the year. That way there is less chance for corrosion or for contaminants to damage the regulator while it is in storage for an extended period. Talk to your dive center’s staff to find out their recommendations on other aspects of service that will be important to your particular regulator.