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Welcome to Dive Gear Reviews, a comprehensive guide to scuba diving equipment. Scuba diving is an expensive pursuit, so looking up reviews for a particular article of equipment is a wise precaution before investing any hard-earned money in it. However, consumer reviews may or may not be written by an experienced diver, and magazine reviews could be suspect due to the advertising ties of the publication in question. Dive Gear Reviews provides cross-referenced reviews assembled by an expert, making it possible to see at a glance what multiple sources said about a particular piece of scuba equipment. If one magazine loved a scuba regulator or a dive computer, but the consumers hated it, that information will be found here.
28
October

Scuba Regulators – Features and Formats

Written by Dive Gear Reviews Editor. Comments Off on Scuba Regulators – Features and Formats Posted in: Scuba Product Guides, Scuba Regulators
Scuba regulator kit

A full regulator kit with first stage, second stage, octo and gauges.

Divers learn about regulator basics during Open Water instruction, such as the division between the first and second stages and the fundamentals of how a regulator delivers air at ambient water pressure. However, basic and intermediate scuba classes almost never teach a diver about the mechanics of how a regulator works, and as a result a diver purchasing her first (or even second) regulator probably does not know what an “unbalance diaphragm” is, or how that stacks up against other regulator formats.

Piston vs. Diaphragm

First stages work on either piston or diaphragm designs. The piston first stage is the older design, and frequently depicted in “How Stuff Works” type documentary programming on scuba gear. Piston regulators have fewer moving parts than diaphragm regulators, but part of the piston mechanism is exposed to the water, and therefore more prone to corrosion. As a practical matter, for the typical recreational diver there is little difference between the two systems.

Pistons are usually thought of as more reliable, because of the simple principle that fewer moving parts means fewer chances for something to go wrong. However, the owner of a piston regulator cannot afford to skimp on regular maintenance, as someone needs to open the first stage of a piston regulator from time to time to check for corrosion. If something goes a little awry with your regulator, a piston is supposedly more likely to continue working than a diaphragm, but a diaphragm is more likely to keep working just fine and never require major repairs or replacement parts if properly cared for.

Balanced vs. Unbalanced

Unbalanced diaphragm first stage

The inner workings of an unbalanced first stage.

Both types of first stages come in balanced and unbalanced formats. With a balanced diaphragm maintains stable breathing resistance even as the tank pressure changes. With an unbalanced system breathing resistance increases as the tank empties, although the degree to how much resistance increases depends on the ratio between the tank pressure and the ambient water pressure. An unbalanced diaphragm regulator fitted to a tank with a few dozen bar worth of air (or 500 psi) should make breathing noticeably harder at 100 feet, but the difference might be negligible at 15 feet.

Another point to notice is that second stages also come in balanced and unbalanced formats. Obviously, a diver who wants to use breathing resistance as a back-up for a tank gauge should assemble an all-unbalanced system.

Control Knobs

Most regulators come with a control knob or venturi lever. This is a simple adjustable control for turning air resistance up or down. A diver might want to turn resistance up to avoid free flow accidents on the surface, or turn it down to deliver more air when working hard underwater.

Nitrox Compatability

Nitrox compatibility of up to 40% is a fairly common feature for regulators on the market today, but it is far from universal. The Mares Prestige 12S, a Scuba Diving Best Buy from only two years ago, is an example of a solid mid-range regulator that is perfect for a diver on a budget, but lacking in Nitrox compatibility. The Prestige 12S can be refitted for Nitrox, but it lacks this capacity out of the box, and there are plenty of regulators on the market just like it. Never assume that a regulator is ready-made for Nitrox, let alone other mixed gases.