How to choose your regulator

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Αντιγράφοντας από το DIVE Magazine εδώ

Report Mark 'Crowley' Russell

A regulator set is going to be one of the most expensive investments you make when it comes to dive gear. A quick web search gave me a price of £325 / €415 for a basic package, which included the first stage and primary second stage / alternate second stage / combination SPG and depth gauge console – in other words, the mainstay of tropical dive shop rental equipment. When people ask me for advice regarding an inexpensive entry-level purchase, the 'rental set' is my first recommendation – it will be the least expensive, but hard-wearing and easy to service – otherwise dive centres wouldn’t use them!
Regulators are complex affairs and have a lot of features hidden behind some very technical jargon. Before you make a purchase, you need to consider what type of diving you plan to do, and which of these features are relevant and necessary. If, like me, you 're purely a warm water diver then pretty much any regulator will be fine, but if you’re likely to be diving in cold, murky water, or perhaps at a point where you are considering an adventure into technical diving, then your options become more limited, and your choices more important.
There is no regulator on the market that could be classed as a poor choice, as long as you’re using it within the limits of the manufacturer’s specification, the recommended environment, and your own training. Purchasing a regulator above your requirements is absolutely fine if you can afford it and may provide greater flexibility later on in your diving life, but there will be knock-on effects in terms of maintenance costs, for what may be no real difference in terms of practical application
Many regulators are sold as individual components, some are sold as a complete set. It doesn’t really matter either way, but an all-in-one package eliminates some of the doubt. What I’ve tried to do here is cover each component, with a few pointers on technicalities that may crop up during your search. Remember as always that this article reflects the 'Easy Diving', entry-level purchase of your first dive equipment. Regulators are complex, there’s quite a lot to wade through, so please bear with me!
First Stage
First stage regulators – as in, the bit that you connect to the tank – are where a lot of the features will be found, although some of these are internal, and not obvious to the untrained eye. One of the first topics of discussion about first stages are the merits of 'balanced' versus 'unbalanced' or 'overbalanced' regulators.
In simple terms, the breathing characteristics of a balanced regulator remain unchanged regardless of the pressure in the tank – an unbalanced regulator is directly affected by tank pressure, meaning that breathing effort increases slightly as the tank pressure drops, and an overbalanced regulator increases the airflow as you dive deeper. Note that the 'increase in breathing effort' in modern unbalanced regulators is very small, and only really becomes noticeable if a diver is running very low on air (as in, less than 30 bar / 450 psi or so) which, if you’re following safe recreational diving practices, means you should already be at or near the surface.

Connecting a first stage to a dive tank

Some people claim that unbalanced regulators will worsen your air consumption, and although there is a little bit of truth in that, the difference is almost negligible; good air consumption is achieved through practice and technique, not regulator design.
Practically speaking, for most recreational diving, it doesn’t matter which you choose. The least expensive regulators will be unbalanced, but their simpler design means they are also cheaper to service. Balanced and overbalanced regulators are more expensive to purchase and service, but cover a broader range of diving.
In the discussion about balanced or unbalanced regulators, you will also hear about piston and diaphragm regulators. The piston is the more simple design, with a hollow metal piston and compensating spring opening and closing the air supply on demand. Diaphragm regulators are more complex, with a flexible rubbery disk pushing some other parts around to accomplish the same thing. In general, low-spec. unbalanced regulators will be piston based, higher-spec overbalanced regulators will be diaphragm based, with balanced regulators being either/or. For recreational diving, there isn’t a great deal of difference in terms of their practical application, with the exception of cold water diving.
Diving in water temperatures around 5°C or less requires a regulator that can cope with the combination of the cold water and the cooling properties of expanding gas, which can cause the internal workings of a regulator to freeze, resulting in an uncontrollable free-flow. Diaphragm regulators come highly recommended for cold water, but insulated piston regulators are also available. Kits can be fitted, but it’s best to buy a cold water regulator outright if that’s where you’re going to be diving. Always check that the manufacturer explicitly recommends its regulator for cold water use.
An 'environmental seal' prevents water entering the first stage, along with silt, sand, salt and other particulate matter so they are essential for diving in murky water. Some regulators (diaphragm in particular) are sealed by default but note that an 'environmental seal' does not automatically guarantee that the regulator is suitable for cold water.
One more obvious difference is the method by which the first stage attaches to the tank valve. They are the more common yoke (or A-clamp), which is secured by fitting the regulator over the valve and tightening the screw at the back, or DIN regulators, which screw directly into the tank valve itself. Scuba tanks are (broadly speaking) either 'International' (Int, for short) with a fixed tank valve opening, or DIN, which have a removable plug in the valve. This means that yokes can be used with both types of tanks, whereas DIN regulators require an adapter to connect to International tanks. The advantage of DIN connections is that they create a much stronger seal, so they can be used with higher tank pressures (although this is outside the realms of recreational diving), but they also help to eliminate annoying leaks caused by perished o-rings, and are slightly less bulky than yoke adaptors. They are often promoted as a safety measure to prevent the regulator being dislodged in overhead environments, but it’s unlikely that this would happen to a yoke connector either. Tanks with DIN compatible valves are becoming increasingly common around the world, so to some extent, it’s a bit down to personal preference. For that reason I personally prefer DIN, but if you’re not sure, then the yoke is just fine.
When it comes to ports, all current regulators have at least one high pressure (HP) port (for the SPG or integrated air computer), and four low pressure (LP) ports (two for the breathing regulators, one for the inflator mechanism, and a spare for drysuits). Higher spec regulators usually have more (two HP and up to six LP), mostly intended to provide extra support and redundancy for technical diving, although if you plan to use an air-integrated wireless computer (more in the next article), then I highly recommend investing in a regulator with two HP ports, one for the wireless transceiver, and the other for a backup analogue SPG.
One final, frequently asked question is 'can I use nitrox with my regulator'. The short answer – for recreational diving with a maximum limit of 40% oxygen in the mixture is yes – you can use any regulator you like. However, International standards require that anything over 40% O2 is treated as pure oxygen, and there are also countries where regulations recommend that you have oxygen clean and compatible regulators (with a different attachment) for diving with any gas mixture containing more than 21% O2. For these reasons, some manufacturers do not explicitly state that their regulators are nitrox compatible, which leads to some confusion. To repeat – ALL scuba regulators can be used with recreational nitrox, assuming that you’re diving in locations not governed by meddling regulatory busybodies!
Second stages
As mentioned in the introduction – most regulators on the market comprise a first stage and a primary second stage (the bit you stick in your mouth) with the alternate (octopus) and SPG sold separately. You can, therefore, mix and match to some extent, but the safest bet is to choose the manufacturer’s recommended alternate second stage.

An octopus (alternate air source), a second stage regulator and set of gauges
The balanced / unbalanced question arises again for second stages but beyond the cost of servicing, has less relevance to recreational diving than the same question for first stages.
Many second stages have a switch which is often labeled Dive/Pre-dive, or simply +/-, and is often mistaken as an 'increase or decrease airflow' switch. This is not the case. It’s called a Venturi switch and very slightly changes the internal air space inside the regulator. If you look inside the mouthpiece on some regulators, you will see a plastic shield moving in and out of position when you operate it. Breathing is slightly easier with the venturi switch open, but the most practical application of the device is to stop unnecessary second stage freeflow – either before the dive when you hit the purge button to clear the regulator, or underwater in a bit of current. Closing the venturi switch will prevent this from happening.
Some regulators do have a control to adjust the air flow – these are usually higher-end second stages and are useful, but not essential, if you’re going to be regularly diving in deeper water.
Submersible Pressure Gauges (SPGs)
The two options for keeping track of your tank pressure are integrated air computers (wireless or otherwise), or the standard analogue SPG. Computers are very expensive, analogue SPGs are available from around £35 / €50. I always recommend that a diver, at least, possesses an analogue SPG, even if they choose not to use it in favour of an air integrated computer. If your regulator has two HP ports, you can attach it as a redundant backup for the computer, or if not, it’s worthwhile having one in your spares kit. I have lost count of the number of times people relied solely on their integrated air computer and then… the battery died. In most situations, it’s easier to fit the spare SPG than change the computer battery.

Set of gauges with a depth gauge on the top, SPG on the right
Depth gauges
If you don’t plan to buy a dive computer, then an analogue depth gauge is essential, and most people opt for the combination SPG/depth gauge console, which is why I include it here. Having a backup analogue depth gauge in case of computer failure is not quite as essential as a backup SPG; you might be able to work around it with some careful team planning at an appropriate (familiar, shallow) dive site. however, clearly this should not be standard dive practice!

As with all dive gear, the Internet is full of discussion about the many different regulators and the merits of each particular feature they might have. The most important thing is that you buy the right regulator for you, and understanding a little bit of the jargon may help you save money by avoiding unnecessary complexity. Next we’ll have a look at some of basics involved in buying a dive computer.