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Choosing a Buoyancy Compensator (BCs) and Dive Regulator

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So you have the basics, what is next in term of gear purchasing? For many it’s a Buoyancy Compensator and Dive Regulator. The BC is a crucial piece of dive gear. It not only allows us to control our position but also holds the tank. BCs come in two different basic configurations. The jacket style generally has a bladder that wraps around the diver as it inflates while the back inflate has the bladder entirely on the back. The jacket style is the perhaps the most commonly seen in use by new divers. The back inflate is however very popular with many experienced divers. A jacket is shown on the left and a back inflate on the right.

The BC has an air cell to inflate and deflate, and accomplishes that via the power inflator. A BC power inflator is a device that is connected to the bladder by a corrugated hose. This hose generally is located on the left side and connects to the BC in the area of the shoulder, though some are connected in the center of the air cell. The power inflator is also connected to the tank by the regulator’s low pressure inflator hose. By pressing a button air is allowed to flow into the BC. Another button is used to control a valve that allows air to escape the BC. When venting or allowing the air to escape the BC, the inflator needs to be raised above the level of the connection to the BC or a trap – similar to that under your sink – is formed and the air cannot escape. Many BCs however also have additional valves known as dump valves to allow air to be vented without using the power inflator. When using the power inflator to vent, some models require the diver to get nearly vertical in the water. Dump valves are often located on the right shoulder and the bottom of the BC on either side, allowing the diver to vent air without getting vertical. BCs may have pockets, D rings, pouches to contain weights, and numerous buckles to hold things together. There are some BCs that have very little beyond a few d rings; these are known as minimalist or basic harness type BCs. Commonly referred to as “back plate and wing” BCs they are fully customizable in size, features, and function and also tend to cost much less than other BCs. They consist of a stainless steel, aluminum, or kydex plate, a simple one piece harness made of two inch nylon webbing, and a bladder (the wing) that is removable from the set up. Wings are available in different lifts to suit the type of dives, cylinder or cylinders used, and the amount of weight the diver requires. They commonly have three or four D rings, a buckle, and little or no extra padding, yet are very comfortable in the water. Some believe that back inflate BC’s tend to push a diver forward in the water. This is a myth. Back mounted BC’s on a properly weighted diver DO NOT push a diver face forward into the water.

Jacket Buoyancy Compensators are more commonly used and often have many “extras,” but this does not mean they are the best choice for every diver. Pockets often seem to be poorly designed and inconveniently placed. There are often more D rings than the three or four found useful by most divers or on some models none at all.

How then do we choose a BC? The priorities must be comfort, quality, and features specific to the needs and preferences of the individual diver. Price is not a reliable barometer of any of these, and paying more does not guarantee you a “better” BC. What matters is what the BC will do for you and how it will suit your needs.

What I look for in a BC is function and simple is better. Why? Because unnecessary complexity creates a more confusing piece of equipment, as well as creating too many potential failure points; it also involves unnecessary expense. There is simply no need for a diver to spend more than a few hundred dollars on a BC. That it will serve you for many years doing the types of dives you do, is the ultimate goal in selecting a BC or any other piece of gear for that matter.

Beware of claims that exotic BC features will make you a better diver. The only thing that will make you a better diver is good training and diving regularly. I can take any BC that I can get on –regardless of size, style, or configuration and within 10 minutes get horizontal and have full control over my buoyancy. This is the result of practice, experience, understanding the effects water has on me and my equipment, and proper weighting and trim. None of this is beyond the grasp of the average OW diver who wants to achieve this level of competence. A BC is a tool, and as with any tool, simple is usually better. The next items we’ll look at are dive regulators.

Dive Regulators

The item that allows us to breathe underwater was invented many years ago in a number of different forms. Regulators were used in industrial applications long before their relatively recent adaptation for underwater use in SCUBA. The modern SCUBA regulator is commonly attributed to two Frenchmen, Emile Gagnan and Jacques Cousteau. In the 1940s, they began to work on a design that allowed a diver to descend into the water and be supplied air at ambient pressure (i.e. as the water pressure increased the amount of air the regulator delivered also increased). This kept the pressure of the water from collapsing the diver’s chest cavity – a very good thing indeed! It also opened SCUBA to the average person. In the early days of diving, regulators (and most SCUBA gear) were sold in sporting good stores and through mail order. Dive shops were rare and training was done by ex-military divers or one bought a book, ordered the gear, got air from somewhere, and went diving! Things are arguably much better now.

Those early regulators were of the double hose design (above) made famous by shows such as Sea Hunt. They worked well and were the most common type in use until the single hose we know today came into regular use in the 1950’s. The single hose regulator is commonly divided into two basic types: the piston and the diaphragm. Each of them has subtypes known as balanced and unbalanced. The balanced regulator basically delivers air at the same rate regardless of the pressure in the tank. Unbalanced regulators tend to get stiffer or breather harder as the tank pressure drops. What concerns us in this work is what reg do we really need and why.

A complete regulator set consists of several parts: the first stage, second stage (there are commonly two of them, a primary and an alternate), the submersible pressure gauge (SPG), and a low pressure (LP) inflator hose. Each of these plays a vital role in breathing underwater. We’ll look at each of them in turn and then try to offer some advice on choosing a set.

The function of the first stage is to reduce the high air pressure in the tank to what is known as an intermediate pressure and distribute it to the other components in the regulator set. This intermediate pressure varies from regulator to regulator but is usually in the 135 – 145 PSI range. This is the pressure that is sent to each second stage and the LP inflator hose. The SPG receives the full pressure in the tank though it is restricted by a much smaller diameter orifice in the first stage and at the gauge itself. The hoses to each component that receive the intermediate pressure are of the same type and have the same size fitting at the first stage. The high pressure (HP) hose to the SPG usually has a larger diameter fitting. This is purposely done to avoid putting a low pressure hose on the high pressure side that would result in a rather spectacular failure of the hose and possible injury to those nearby. The second stage on many regulators is a demand lever type. The user inhales or pushes the purge button and the diaphragm collapses onto the lever, allowing air to enter the chamber and be inhaled. The first stage responds to depth and pressure and by way of the demand valve in the second stage, delivers a proper volume of air as depth increases or decreases. Many second stages have adjustment knobs that will allow the diver to fine tune the amount of air they receive and/or vary the inhalation effort required to depress the lever. While a very nice and convenient feature, it is not absolutely necessary for the average recreational diver to have. It adds to the cost of the unit and for the casual diver, makes no real difference over a well – tuned, non – adjustable one.

The primary second stage (the one in the diver’s mouth), often has adjustment knob and a lever known as a venturi lever that is open or closed. Open, the venturi lever allows air to flow unobstructed to the diver. Closed, it deflects some of that air back up against the diaphragm making it harder to depress and accidentally cause a free flow.

The LP inflator hose has a quick disconnect fitting that attaches to the low pressure inflator on the BC; it allows the diver to add air to the BC. With some exceptions, these are standard connections. Non – standard connections are used on BCs that have a different type of inflator, known as an integrated alternate, integrated octo (short for octopus), or integrated safe second.

These inflator mechanisms combine a secondary breathing regulator with the power inflator. Hoses on these regulators have fittings that will only fit those mechanisms. The integrated octo is the subject of much debate. It does eliminate a hose from the regulator, which theoretically improves streamlining. It is also said to be easy to locate at the end of the power inflator. However, it also requires the donor in a low or out – of – air situation to donate the primary. There is nothing wrong with that for those who have been well trained in donating in that manner.

The problem is that many, if not most, new divers are not trained that way; they have been taught using standard setups that have a separate octo. If you choose a BC with a non standard inflator as described above, it is completely reasonable to ask the shop to provide instruction in the water on its use. If they refuse, walk away. Do not attempt to use or purchase one of these units without instruction. You must control your buoyancy while donating, and for one trained on a standard set up this means venting while ascending. To vent with one of these units while breathing from the secondary, you’ll have to remove it from your mouth repeatedly or use the shoulder dump on the opposite side (if the BC has one). This is not something one wants to do in a stressful situation without being completely comfortable in doing so. I do not recommend these units to my students and I will not permit them in my Advanced Open Water class without seeing the diver use it. There are some class exercises in which this type of unit cannot physically be used at all. Another issue with these BC/regulator combinations is that if the diver decides to travel with one, it is also advisable to also take a spare hose for the integrated alternate because if that hose fails it may be difficult to find a replacement at the travel destination. It is advisable in any case to have a spare standard inflator hose for the regulator normally used with the BC equipped with this unit. In the event that the diver is unable to use their BC they can still use their regulator with a BC equipped with a standard inflator. If this is the case they will still need to have a standard octo that they can put on the regulator or be fully familiar with buddy breathing as they no longer are able to use the integrated second stage that is still attached to their own BC. I personally see too many unnecessary issues that can develop with the use of the integrated octo to make it a viable alternative.

While no part of the regulator is more important than another as they are all vital, the Submersible Pressure Gauge (SPG) is the most important gauge one can have. It tells you how much air is in your tank. In the early days of SCUBA, divers did not use them; they had another mechanism that indicated when they were running low on air. Called a “J” valve, it had a lever that functioned as a reserve supply. In the up position this lever gave the diver roughly 300 PSI of air that could be used for the ascent. The issue with these valves was that if the lever got hit or accidentally tripped, the diver might not know it! When the regulators began to breathe stiffer – indicating the air supply was getting low – the diver would reach back and pull down on the steel rod connected to the lever on the valve. With the valve already tripped, the diver had no reserve and had to make what could be too rapid an ascent to the surface, or hope a buddy was close enough to donate for a safe ascent. The SPG was a major step in resolving this issue.

The SPG is a simple device; it measures the pressure in the tank and indicates the reading on a dial, in most cases. While there are digital gauges available, including ones integrated into the dive computer, they offer no additional benefit but do add an additional potential failure point, as they are dependent on batteries. SPGs often indicate pressures up to 5000 PSI and 4000 PSI gauges are common. They are relatively maintenance – free other than rinsing, and changing the O rings in the connection to the hose. As with any mechanical device they can fail, especially if water accidentally gets into them via the first stage and is not removed before the regulator was re-pressurized. In such a case the gauge can be destroyed and the diver put at great risk. Anytime an SPG begins to act strangely it should be replaced. Gauges can be had from $40 to $80 depending on quality. Spend the money; your life is worth much more than that.

We’ve now looked at the essential parts of the modern SCUBA regulator and have briefly described their function. If you want to buy one, what should you look for? First of all, how much do you realistically have to spend? Do you want a piston or diaphragm? For the average recreational diver, it really makes no difference no matter what the shop may tell you. Balanced or unbalanced? This one can make a difference. A balanced unit will deliver the same volume of air with the same effort no matter what the depth may be or how low the tank gets. This is important in my opinion, as it eliminates one potential cause of diver stress (i.e. variable breathing effort). Anything that does that is good, so a balanced one it is!

The next consideration is the water temperature where the diver expects to dive. Warm water (for most regulators this is defined as above 40 degrees Fahrenheit) makes no real difference. Colder or cold water does. Some regulators are not designed to be used in cold water and should not be, due to freeze – ups. Diaphragm regulators tend to be more resistant to this, so if it’s the Great Lakes or deep inland quarries, a sealed diaphragm makes the most sense. Another factor to consider is water quality. Some regulators are known as environmentally sealed, in that no water or other contaminants get into the first stage at all. Some allow water into parts of the first stage. No special unit is required for diving in warm, fresh water that is relatively clean, or for saltwater when the unit will always be carefully rinsed. If there is a lot of sediment in the water or other gunk that could cause a problem, a sealed regulator is called for whether piston or diaphragm. For the strictly warm – water diver who takes good care of their gear, most any first stage will be more than adequate. For anything else, I’d personally only choose an environmentally sealed first stage of the diaphragm type.

Now, what second stages should we consider? The temperature of the water continues to have some influence here. For cold water, I like the adjustable second stage that helps to regulate the amount of air I can get at one time. It reduces the chance of a free – flow due to the first stage freezing as a result of too much air being delivered. In warm water, I use both adjustable and non adjustable second stages. One feature I also look for in a second stage is whether I can disassemble the stage underwater to clear it of anything that might get inside it; all of my personal regulators enable me to do this. I have seen dirt, twigs, and other stuff get into a regulator; being able to fix that without surfacing is convenient, while preventing the need for the diver to surface. The next item to consider is the mouthpiece. There are many choices and no diver should have to deal with an uncomfortable one. There are even custom ones that can be molded to the diver’s mouth. The mouthpiece should be comfortable enough to allow the diver to do a dive of any length with no jaw pain or fatigue.

It might seem prudent to save a few dollars by buying an alternate second stage (octo) that is cheaper than the primary; after all it will hardly ever be used. However, when it is used it will be during a high stress situation (you are donating to an out of air diver) and that is not the time to be dealing with inferior equipment. The octo should be of equal quality to the primary. You should be able to adjust or detune it enough to prevent it from free – flowing and still deliver an adequate volume of air. Again I do recommend that divers choose a standard octo over the integrated type. There is less maintenance involved, they are most likely what you were trained with, and usually they do cost less than the integrated. Standard octos can also be used on most BC’s the diver will ever rent or borrow. The brief summary on second stages is this: For warm water, any second stage of reasonable quality will do. For colder water you should get an adjustable second that can be disassembled under water. Match either with a standard octo of equal quality.

The LP hose is a simple matter of finding one that is the right length for the BC one is using. It should also have the correct connector for the LP inflator. Remember that if the hose has been used on a BC with an integrated inflator it most likely will not work on a standard BC. A second LP hose can be added if one chooses to get a dry suit. This will be connected to the inflator valve on the suit.

The high pressure hose and SPG are the last parts of the regulator that we need to look at. The most common configuration new divers are likely to be exposed to is the console set up. The console will always include at least the SPG and a depth gauge or dive computer. There may also be a compass. If you do plan on getting a console setup, make sure it is organized in the way that suits you best. If it has a compass, try to get a console that will allow you to see both the compass and the depth gauge at the same time; some do not and make it difficult to successfully navigate a course. When choosing a hose length, select one that allows you to easily lift the gauge to see it yet without excess length to get in the way otherwise.

To sum up about dive regulators: For warm water dives any regulator (piston or diaphragm), by any major manufacturer will be completely satisfactory. There is no need for a warm – water diver to spend extra money for a cold – water regulator. An environmentally sealed first stage is always a good option though. For cold water divers, the best choice would be an environmentally sealed, diaphragm first stage, coupled with an adjustable second stage to lessen the chance of a free – flow. For both setups I recommend a standard octo rather than an integrated one. Most new divers are trained with the standard setup and if you are partnered with a new buddy it will lessen or eliminate any confusion in a low on or out of air situation. Finally choose a console if not going with wrist mounted gauges – that will allow you to view the compass and depth gauge at the same time. For more in depth information on choosing equipment watch for my new book that will be available in the spring of 2011. “SCUBA: A Practical Guide for New Divers” will be available on disc, pdf download, Kindle, and in limited print editions.


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