Regulators

The scuba regulator is the fundamental invention which makes recreational scuba diving possible. The regulator reduces the pressure of the air coming from your tank to the ambient water pressure and delivers it to your mouth for you to breathe.

The scuba regulator has two parts: a 1st stage and a second stage connected by a hose. The 1st stage connects right to the tank; the 2nd stage is the contraption behind your mouthpiece. Both have an important function in regulating air flow throughout your scuba system.

First stage scuba regulator
The 1st stage is a valve that lowers the air pressure coming from the scuba tank. It is really similar to a water tap; without a tap the water pressure pushes the water out of your faucet at a gushing full force. With a tap you can control the rate of flow. The 1st stage scuba regulator does the same thing: instead of the air gushing out at 232bar it reduces the flow an intermediate pressure.

Inside the first-stage scuba regulator are pressure chambers separated by valves or pistons. Depending on the ambient pressure (which changes according to your depth) the first stage will change the rate of air flow. It is like a tap that turns itself up and down depending on your depth. At higher pressures it opens up; at lower pressures it closes. This ensures that all devices using your air (like the hose used to inflate your BCD) function properly at any depth.

When you breathe in through the mouthpiece you suck air out of the breathing chamber. This lowers the pressure inside the hose below the ambient water pressure. The water pressure pushes in a diaphragm or piston, attached to a valve, to open the air flow; letting in enough extra air to balance the air pressure again. Doing this means the air pressure flowing to your mouthpiece is always balanced against the ambient water pressure.

The 1st stage will have several outputs coming out of it. Some are at high pressure - these go to your tank pressure gauge. The others are at the lower, controlled pressure - these go through the hose to your second stage, your spare regulator (a.k.a. the "octopus") and to the inflator for your BCD or dry suit hose.

Second stage scuba regulator
The second stage regulator takes the manageable pressure coming from the 1st stage through the hose and delivers it to your mouthpiece in a way that is comfortable to breathe. Where the 1st stage is only concerned with letting air flow into the hose the 2nd stage has more complex machinery which handles both inhaling and exhaling through the same mouthpiece.

Like the first stage the 2nd stage scuba regulator uses a diaphragm or piston to open a valve. Breathing in from the mouthpiece reduces the air pressure inside the chamber, water pressure pushes the diaphragm in, which opens the intake valve. When you stop inhaling the pressure in the chamber balances and the valve closes. The result is an air delivery system which supplies air only when you are inhaling and does not leak air constantly through the mouthpiece. A well balanced and well-maintained scuba regulator does its job so well that breathing feels natural and effortless despite the all mechanics involved.

The second stage scuba regulator also has a purge or exhaust valve, which lets your exhaled air out of the chamber, but doesn't let water in. When you exhale into the second stage scuba regulator the pressure inside the chamber becomes greater than the ambient pressure. The exhaust valve is a simple one-way valve which lets this air escape.

A second stage scuba regulator also has a purge button which forces the intake valve to open. When the purge button is pressed air will flow continuously into the chamber and escape either through the mouthpiece or the aforementioned exhaust valve.

Because the regulator is such a vital piece of equipment many scuba divers choose to buy their own scuba regulator instead of renting one from the dive shop. When a scuba diver has used a few different scuba regulators, on numerous dives, he/she will notice that they all have slightly different "action" - some feel looser or tighter, some will deliver air more forcefully, others will have a slight "suck" to them. The goal of all regulators is the same: to deliver air on demand at ambient pressure. Comfort with a scuba regulator depends on how the diver breathes; which is different for everyone. Though a helpful assistant at our 2DiVE4 shop can recommend "the best" regulators, from the most respected manufacturers, in truth no one can tell you which regulator "feels right", except you.

As a novice scuba diver renting or borrowing equipment from a dive shop always take note of what scuba regulator you are using and whether you like how it feels. When you find the one which makes your breathing feel effortless remember its make and model. When you decide to buy your own scuba regulator you will know which one to get.

When shopping for a scuba regulator here are some things to consider:

• Ergonomic design and easy to hold
• A purge button which is easily pressed even when wearing 6mm neoprene gloves
• External controls which let you make fine adjustments to air flow
• Non-corroding metals like titanium or chromed brass
• Diaphragm vs. piston mechanics. Many divers prefer diaphragm regulators for its smooth movement and its moving parts are less
• Balanced vs. unbalanced regulators. Almost all regulators are balanced. Do not buy an unbalanced regulator.
• Always buy new. Do not pick up a cheap second-hand regulator; it may be faulty or reconditioned
• Look for a warranty
• Swivel joints on the second stage offer improved ease of movement
• Hose should be soft and flexible