From scuba diving news .com, the author apparently has a bias toward diaphram regulators.
Let's look at the various types of regulators.
The simplest and the type that has been around the longest is the piston regulator. This type of first stage (the part that connects to the scuba tank) has fewer moving parts and has simpler maintenance requirements. Another advantage of a piston first stage is it's high air flow. Typically piston regulators can generate higher air flows than other types of first stages, but this comes with a price. Piston first stages are not as reliable in colder water than other styles, but some manufacturers have incorporated various devices and technology to help prevent regulator malfunction in these conditions.
The next style of first stage is called the diaphragm style. Diaphragm first stages are the best for cold water, silty conditions, or even for salt water, as the moving parts are protected by a diaphragm. These regulators have more moving parts and can require a bit more maintenance due to their complex designs, but the reliability overrides this concern.
Some diaphragm first stages also incorporate what is known as "environmental sealing". This technology uses a second diaphragm on the first stage to give extra protection against very cold
water and under ice diving conditions. Many divers choose environmentally sealed first stages due to the fact they can be used in any type of diving circumstance.
First stages also fall into two categories of "balanced" and "unbalanced". Balanced first stages will deliver the same flow of air, no matter what the tank pressure is, while unbalanced first stages will allow less air to flow as tank pressure drops.
Unbalanced first stages are usually at the lower end of the price spectrum.
Lets' look at the second stage (the mouthpiece) next.
Most second stages can be grouped into two major types: balanced and unbalanced. There are some other features associated with the second stage that may help with a buying decision, and we'll cover those later. First, though, let's look at the unbalanced second stage.
The lever that opens the valve upon inhalation is controlled by a spring inside the second stage. In unbalanced (some refer to this type as a "mechanical") second stages, the spring is rather stiff. The advantage of this is that the second stage is less likely to flow a lot of air in "free-flow" conditions; in other words, the second stage is less likely to malfunction. The downside to an unbalanced second stage is that the air flow is reduced, consequently not as easy from which to breathe.
On balanced (sometimes referred to as "pneumatically balanced" or "air balanced") second stages, the spring used is of a lighter construction, with air balancing or counteracting the spring tension, thus making these second stages extremely easy from which to breathe. These tend to be on the high end of the price range.
Other features on many second stages include venturi assist levers, which control the direction of airflow. Sometimes these are referred to as "free flow" controls. The function of these levers is to direct the flow of air through the mouthpiece in a straight line (easiest air flow) or slightly interrupted (less likely to flow air continuously). Another feature on higher-end second stages is an adjustment knob, which controls the regulator "cracking effort"; the effort required to cause the lever/valve inside the second stage to flow air to the user.
These have some benefits, in that the user can control how easy the second stage breathes. In deeper dives, the control is opened for maximum air flow, while diving into currents requires the control to be slightly reduced so the second stage does not waste air.
Maintenance is an important issue. Remember, we are dealing with life support gear. Many manufacturers offer a lifetime warranty on their regulators, provided the original purchaser brings the regulator in for service to an authorized dealer at least once per year. The dealer will inspect and clean the regulator and replace any parts needed to keep the system in top condition, and adjusts it to factory specifications.
So to summarize, the best for all conditions would be a balanced diaphragm first stage with a pneumatically balanced second stage.
The least expensive would be the unbalanced first stage coupled with a mechanical or unbalanced second stage.
When it comes to putting a system together, manufacturers will package a first and second stage together. There are many options in the marketplace. The best idea is to consult with an expert at your local dive center for suggestions and guidance on selecting the regulator that's right for you and the conditions in which you're planning your next diving adventure.
About the author:
Colin is an accomplished underwater photographer and scuba instructor. He teaches scuba diving for The Underwater Connection with three locations in the Milwaukee, Wisconsin area. His website is subsurfacephoto.com
