Dive Right In Scuba - Scuba Diving Blog

   SCUBA regulators and their associated features have been a widely discussed and hotly debated topic. Oftentimes new divers are left confused and frustrated at all of the varied expert opinions out there from experienced divers and instructors. While everyone has their valid opinion on the matter, in all reality the perfect regulator for the individual diver should be left to the person who will be depending on it. In concept, a SCUBA regulator is a simple, mechanical device with a rather simple purpose. That is to take gas from a high pressure and step it down to a pressure that can be breathed safely by the diver. Along the way, there are differing ways of achieving this end goal, with a number of added features and capabilities thrown in to enhance as well as make the dive safer and more enjoyable. Given this, let’s break down the individual options offered in popular SCUBA regulators and their associated benefits. Please bear in mind that all of this information is correct at the time of writing and like anything with the SCUBA industry, can change as time goes on.


DIN vs. Yoke SCUBA Regulators

DIN Regulator

Yes, it has a funny little name. However, the term “DIN” is actually an acronym for Deutsches Institut für Normung which is the German national standards organization. So, it’s rather easy to surmise that DIN is used rather extensively in Germany and Europe. It’s also used as the main type of SCUBA regulator connection for technical and cave divers. The reason for this is that the DIN connection carries with it less of an entanglement hazard than it’s counterpart, the Yoke connector. The DIN connector consists of a large threaded post with an o-ring at the end that screws into the valve of the tank. When properly connected, the o-ring is captured within the tank valve providing the required seal.


Yoke Regulator

The other type of connector is referred to as the Yoke. This is the most common connection among recreational divers in the U.S. as well as in most vacation destinations. The Yoke connector doesn’t have an o-ring within the connector as it’s contained on the tank valve. The connector itself contains an oblong metal brace that goes over the tank valve. On one end of the Yoke, the connector is the regulator, on the other end, is a knob with a securing bolt. When you place the yoke over the tank valve, the knob gets tightened pushing the regulator orifice into the o-ring on the tank valve creating the seal.


    This question has a simple answer that can often be complicated. If you plan on recreational diving in the U.S. as well as vacationing in say Mexico and the Caribbean, Yoke may be your best bet. If you have designs on going into the more challenging technical diving realm or plan on using high-pressure steel tanks primarily, go for DIN. There is, however, a third option that gives you the best of both worlds. That would be to opt for the DIN connector and purchase a “DIN to Yoke” adapter for a modest price. This would allow you to dive DIN regularly and retain the ability to use cylinders with Yoke style valves when that’s all that’s available to you.


Piston vs. Diaphragm SCUBA Regulators

Piston Regulator

A piston first stage uses a piston that moves up and down against a large heavy tension spring.  When the regulator is pressurized by opening in the tank, the piston moves and allows air to pass the high-pressure seat.  When the pressure inside the regulator reaches IP, then it closes, and air stops flowing.  When you take a breath, it moves and lets air through.  While this is a simplified explanation of what happens, this is basically it. Then we have balanced and unbalanced regulators.  A balanced piston first stage will provide the same IP all the way down until the tank reaches the IP.  An unbalanced regulator will have some IP drop as the pressure in the tank decreases.  In most cases, the balanced first stage would cost more than the same regulator in an unbalanced design. While the piston regulator is simple in design, can provide for high gas flow, and are less expensive to maintain, there is the possibility of freezing up in extremely cold water.  This failure often causes the regulator to fail “open” and free-flow uncontrollably. One great example of a piston regulator is the Atomic Aquatics T-3 regulator. The T-3 is environmentally sealed to keep out sand and salt from the piston and helps prevent freezing.

Diaphragm Regulator

A diaphragm first stage uses a thick piece of rubber (the diaphragm) pressed up against a precision machined metal pin seated on a spring and then the hard plastic high-pressure seat.  There is also a spring pushing on the diaphragm from the opposite direction holding it closed.  When high-pressure gas is introduced into the regulator, the spring against the plastic high-pressure seat opens, and gas flows into the second chamber of the regulator until the IP is reached.  Then the regulator “closes” and this process repeats as you breathe.  The diaphragm design is easily balanced, and today, you’d be hard pressed to find an unbalanced diaphragm first stage. The diaphragm by design has more moving parts than a piston regulator, and service kits might cost slightly more than a piston design.  Diaphragm regulators are a little better for those who are not as meticulous with cleaning their first stage after diving.  They’re also good in all water temperature, as the inner workings are not exposed directly to the water. Some people might tell you that diaphragms don’t have as much air flow as a piston regulator.  While this may be true, there wouldn’t be a noticeable difference in most sport diving (including technical) applications. Apeks diaphragm regulators are among the highest of quality.  These first stages utilize a unique what they call “overbalanced” design.  This means the intermediate pressure supplied to the second stage increases more than traditional balanced models as the diver descends to greater depths.


Cold Water vs. Warm Water SCUBA Regulators

Warm Water Regulators

A warm water SCUBA regulator in the simplest definition is one that is “unsealed” and allows some water to enter the regulator system. Most tend to be on the economic side as they are simpler in design and function. If you’ve dived in a warm water destination and have used rental regulators, there’s a good possibility you’ve already made use of a warm water regulator.  If your plan is to solely dive warm Caribbean type waters then a simple warm water regulator is a good option for you.  

Cold Water Regulators

If you ever dive in cooler waters you’ll need a regulator designed for those conditions. Pretty much any regulator can be used in warm water but not all can be used in cooler waters. The reason for this is that icing of the internal regulator components can occur. Of course bear in mind that it’s not solely the water temperature that causes icing. Expansion and subsequent cooling of high-pressure gasses from your SCUBA cylinder are the contributing cause of regulator icing. Cold water regulators contain an “environmental seal” that unlike the warm water regulator does not allow water or contaminants into the regulator. This seal is quite effective at keeping the moving parts of the regulator from icing up and causing a failure.

If you’re diving in colder waters, the prudent diver needs to understand that even cold water regulators have the potential to ice up. You should take the following steps to further reduce the potential of a regulator ice up:


The easiest question to ask when determining which regulator to get is “will I ever dive in waters that come close to or below 50 degrees Fahrenheit? If that answer is a yes or even makes you think for a second, it would be the best course of action to make the added small investment in a sealed regulator that will allow you to dive in both warm and cold water.


O2 Clean SCUBA Regulators

   In the simplest definition, O2 clean refers to a regulator that has been cleaned using certain approved cleaners and all sediment, contaminants, and other impurities removed from all surfaces of the regulator. In addition, special lubricants and sealing surfaces(o-rings) are used. The reason behind this is that Oxygen or O2 isn’t flammable by itself but is only a single component in the “fire triangle”. The fire triangle is Oxygen, Heat(Combustion), and Fuel.

Well, of course, we have Oxygen and in the event, we have a cylinder of Nitrox, or pure Oxygen…it’s more abundant than found in the atmosphere. With respect to heat, well we have high pressures and friction that can produce heat or a source of ignition. These first two components we really can’t get rid of so we make an attempt to eliminate the “fuel” portion of the triangle. Through true O2 cleaning, we eliminate 3 pieces of the puzzle that can be used as fuel here. First is contaminants, the second is lubricants…by using nonpetroleum-based products, and finally by using an alternative to rubber in sealing surfaces.


    Now, here’s the tricky part to O2 clean regulators. They must remain O2 clean. If you use a true O2 clean regulator on an O2 clean cylinder or do anything to damage the integrity of the O2 cleaning then it no longer remains to be truly O2 clean. With that in mind, how sure are you of that rental tank’s status as it pertains to O2 cleaning. To that end, to ensure a regulator’s true O2 clean status you should probably only use it on a cylinder that you own, that is filled from a source that is O2 clean, and never let someone borrow it.


Luckily, as a recreational diver, you need not concern yourself with true O2 cleaning as chances are you will be diving with nitrox that maintains less than 40% of pure oxygen. Most often you won’t break 32 or 36% as those are the most common mixes. Currently in the dive industry, just about every regulator you would buy new is ready to handle mixes containing up to 40% Oxygen right out of the box. So, as a recreational diver, you’re pretty much covered.  Realistically, you wouldn’t need to be concerned with true O2 clean regulators and cylinders until you enter the realm of technical diving with accelerated decompression and gasses that exceed 70% Oxygen.


Second Stage SCUBA Regulators

    Now that we’ve discussed the first stage SCUBA regulators, let’s take a quick glance at second stage SCUBA regulators. To the new diver, the second stage is the part of the regulator that you place into your mouth and breathe from. They are also simpler in nature and features than the first stage regulator since it only has to reduce the pressure from roughly 140 psi down to a pressure that you can breathe from. Second stage regulators feature a demand valve that opens when you inhale as well as an exhaust port that allows your exhaled air to escape the structure of the regulator. In addition, the second stage SCUBA regulator features a purge valve that releases air out of the second stage allowing the regulator to be cleared of water or other obstructions.


    Second stage SCUBA regulators come in both adjustable and nonadjustable configurations. Most often, nonadjustable second stages are more inexpensive and simpler in design and operation as there is no way for the end user to adjust the work of breathing. On an adjustable regulator, you can adjust the work of breathing via an adjustment knob and/or a venturi lever. Many of the popular second stage regulators on the market feature both an adjustment knob and venturi(or pre-dive/dive) lever.


    As you can see, that at first shopping for a SCUBA regulator can seem daunting and opinions vary widely, SCUBA regulators and their associated features can be broken down into a handful of areas. When shopping for a SCUBA regulator, take a close look at what water temperatures you will be diving(cold water or warm water), what type of connection to the cylinder you need(DIN or Yoke), whether or not a piston or diaphragm appeals to you, and finally…will you be diving Nitrox or a decompression gas. Beyond that, read some reviews and make a decision based on your own personal preferences. Of course, if you’re confused or have questions, the DRIS team is just an email, live chat, or phone call away.


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One Response

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