What is in our dive tanks is pressured air. If we try to open the tank’s valve and try to breath, we would look like an inflated balloon fish. So, we need something to decrease the level of this high pressure coming from our dive tank. Thankfully, we have regulators for this. Regulator is the equipment that helps us breath normally underwater by lowering the pressure.
Regulator consists of two parts. First stage and second stage.
Regulator First Stage
This is the part that is mounted to the valve of the dive tank. What it does is to decrease the high air pressure coming from the tank to an intermediate pressure and send it to the hose of the regulator second stage. This intermediate pressure is about 10 bars/atm (150 psi).
There are two types of connection between the dive tank and the regulator first stage.
These are common regulator types. There are openings both on the tank valve and the regulator first stage. Diver takes these openings together by screwing the clamp finger-tight. There is an o-ring between the regulator first stage and the tank valve preventing air leaks. Diver should not screw the clamp so tight. This will make the demount of the first stage impossible without tools after the dive. Beyond this, there is a possibility for the o-ring to extrude. So, be gentle with the o-ring.
Yoke regulators have a maximum work pressure of 240 atm/bar (3600 psi).
Yoke regulator first stages can only be used with Yoke valved dive tanks.
DIN Regulators (Deutsche Industrie Norm)
In this kind of regulator first stages, there is a screw looking part. This screw part is getting into the DIN valve of the tank (there is a hole in tank valve). Diver is screwing the regulator to the tank valve just like a drilling machine screwing a mountain.
This makes the DIN regulators much more durable against high pressure. More pressured dive tanks below 200 atm/bar (3000 psi) can only be used with DIN regulators. DIN regulators are considered as safer by many of the authorities. O-ring extrusion possibility is less because the o-ring is fully covered with the system.
DIN regulators have a maximum work pressure of 300 atm/bar (4500 psi).
DIN regulator first stages can only be used with DIN valved dive tanks.
Note that tank valves can be transformed to each other. If you remove the adapter from a Yoke valve, it becomes a DIN valve.
Balanced & Unbalanced Regulator First Stage
Balanced regulator first stages will always keep the difference constant between the pressure inside your regulator system and the ambient (surrounding) pressure/outside pressure. By this way, diver can breath comfortably in every depth.
Unbalanced regulator first stages will not keep the pressure constant, causing difficulty in breathing when the ambient pressure increases (when you dive deeper). This kind of regulators are often chosen by dive centers to get used for the confined water dive training because it is cheaper.
This is the stage that you hold in your mouth. When the air comes to the second stage of your regulator from the hose, it stops. Second stages use the demand valve technology. This means that when you want to inhale, you vacuum in and the “door” inside your second stage opens, supplying you enough air. When you exhale, you “close” this door by pulling it with your breath (This feature makes the second stages call demand valves). There is no free-flow; You can exhale comfortably . After you exhale, bubbles go out from your second stage through exhaust valves.
Main duty of the second stage is to decrease the intermediate pressure coming from the first stage to the ambient pressure. This means that if you are on the surface it is 1 atm/bar and if you are at 10 meters of depth, it is 2 atm/bar.
Before Buying a Regulator
- The most important decision making element is the breathing comfort. You should be breathing easily with minimum effort.
- First stage of the regulator should be balanced. This will make you breath steadily regardless of the ambient pressure and/or air pressure in your tank.
- My personal advise for you is a DIN regulator that I have mentioned the advantages above.
- If you are planning to take some photos u/w, I suggest you to buy a second stage with an exhaust valve on the side (see the photo). By this way, bubbles will not be photographed as well.
- If you are diving in cold waters, ask for a environmentally sealed first stage.
There are some regulator reviews in DiveWithSeaman.com here that may help you choose a regulator.