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Which Regulator?

Introduction	Anatomy of a Regulator	Buying a Regulator
Considerations	Relevant Links	Recommendations
	Tips

Introduction

Regulators consist of a number of separate and distinct elements which are usually bought together at the same time but which can be combined in a number of different combinations.

This section can be a little more complicated to understand at first. Consequently it has been split into a number of separate sections, each of which builds on the previous one.

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Anatomy of a Regulator

Any "regulator rig" consists of a number of basic components. These are shown below with a brief description:

First Stage
	This is attached to the compressed gas bottle and converts (regulates) the pressure down from the existing bottle pressure (normally up to 300 bar) to an intermediate pressure of 8-10 bar above ambient water pressure, dependent on the manufacturer's specification. It has various ports through which gas can be routed and to which hoses and equipment can be attached
Primary Regulator
	This is the bit which goes in the mouth and is breathed off virtually all the time. It converts (regulates) the final pressure down from 8-10 bar by supplying gas on demand. Hence it's alternate name of "Demand Valve"
Secondary Regulator
	May also be known as the Back-up Regulator or Octopus. It is the spare which is kept in case of an out of gas scenario. In which case you would end up sharing gas with your buddy
Low Pressure Hoses
	Up to four may be typically used :
		One for the Primary Regulator
		One for the Secondary Regulator
		One for the Buoyancy Compensator and
		One for the Dry Suit
	Dry Suit and Buoyancy Compensator hoses normally come free when each of these equipment types are purchased and will not be dealt with here.
Submersible Pressure Gauge (SPG)
	Less formally known as the Contents Gauge. This piece of equipment is dealt with elsewhere within this guide. See "Which Contents Gauge?"
High Pressure Hose
	Connects the Contents Gauge to the First Stage. See "Which Contents Gauge?"

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Buying a Regulator

Regulators stretch from economy versions to those which have gemstones incorporated into them with a price to match!

You can normally specify exactly what you want for each individual element and even buy them at different times, even if it is something as simple as a slightly different length of hose. You can even mix and match different bits from different manufacturers provided that they are compatible. Compatible parts have to work off the same intermediate pressure and use ports of a standard size. Poseidon is the most notable exception, the regulators and hoses generally can't be mixed with other first stages due to certain intricacies in the design.

It can be cheaper to buy all the pieces at one time and negotiate a discount, if possible. If your supplier doesn't have exactly what you want in stock right now, don't be put off - he should be able to order what you need unless he is an unhelpful soul! He may become "squeamish" about mixing things from different manufacturers, but provided that they are compatible then there should be no reason not to do so.

This topic is one on which, unsurprisingly, there is an endless maze of information, graphs and comparisons. As usual there are a number of questions that you can ask:

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Considerations

General
	Is it suitable for the kind of dives I'm doing now?
	Will it need to be replaced if my diving becomes more adventurous?
	Will it resist most of the abuse I'll throw at it or can it be temperamental?
	How easy is it to get spare parts or a service world-wide?
	Is it reliable, proven and tested?
	Will it work well with the equipment I've already bought?
	Is it nitrox compatible?
First Stage
	Is the First Stage a DIN fit? DIN fit regulators are more reliable than A-clamps and are less prone to letting the air fall out when you least want them to, particularly when accidentally knocked. This type of design also causes far less damage to the O'ring and the chance of it extruding is minimised. This is the type of first stage shown above. You can also buy an adaptor to fit A-Clamp tanks and keep things flexible, see "here".
	How many ports does the First Stage have? First Stages for most diving should have a minimum of four low pressure ports and one high pressure port.
	Blanking plugs (right) are used to close off un-used ports. Typically the high pressure port is of a slightly larger size and marked "HP" to ensure you do not accidently attach hoses and equipment to the wrong port. (Blanking plugs are inserted and removed using an allen key.)
	Will the hose routings running off the First Stage be tidy and streamlined or a bit of a bird's nest?
	Is the First Stage of a "Turret" design. ie can you rotate some of the ports whilst holding the main body steady? Turrets can make it easier to streamline some hose routings, whilst some people regard this feature as a potential liability (something extra to go wrong). Generally this feature only helps when stage cylinders are being used.
Primary/Secondary Regulator
	Is it a "Downstream" design? In case of a free-flow or similar failure these will fail open so that you can still breathe off them.
	Can it be easily stripped and does it use standard parts?
	Integrated alternate air supplies such as the "Autoair" and "Air II" are supposed to eliminate the need for a separate octopus, but generally are of poorer performance and are subject to greater wear, tear and failure than a normal regulator, since it is not as easy to properly look after them.
	Is it an "Upstream" design? Upstream designs have to be over-engineered to incorporate over-pressure relief valves, these are additional features subject to failure. Without these features the regulator may fail closed unlike downstream valves which would not - this might mean that you would be unable to breath off the regulator in certain failure modes when you would still be able to obtain gas in "downstream" designs. Some Poseidon Regulators are the most notable types of this design, (Excluding their Cyklon model).
Low Pressure Hoses
	Will I be able to give a second stage (mouthpiece) to an out of air diver in an emergency without them crowding me? Being up close and personal due to too short a hose can result in regulators and masks being dislodged all too easily, particularly whilst surfacing in a stressful out of gas scenario. Having room to move is an essential element in out of gas drills. A 7-foot long hose gives you "room to move" in an out of gas scenario in open water as well as overhead environments where you can't go straight to the surface. It can also be "wrapped" and stored beneath a canister light if you should ever buy one. Shorter hoses can be used in non-overhead environments but 5'3"-5'6" (1.58-1.65 metres) is about the minimum length if you want to "wrap it". The 5' (1.5 metres) standard length hose is just a few inches too short.
	What type of hose is it supplied with? Yellow hoses, whilst more visible, tend to be more buoyant in the water, the yellow coating may also hide wear and tear to the hose itself.
	Is the Hose of a "standard" type and size? Apeks Regulators sometimes use hoses of a larger bore/diameter but you can specify and have a standard hose fitted which will ensure that you can easily obtain spares. There is no measurable benefit to the diver of this type of hose. Poseidon hoses can only normally be used with Poseidon Regulators due to different sizing/features.

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Relevant Links

If you find it difficult getting your head around how a regulator works, then there are a couple of useful links below, which have some helpful diagrams:

	http://www.delportdupreez.co.za/diving/equipment/regulator.html
	http://www.diverlink.com/gear/regulatorfunction.htm

For a discussion of the relative merits of donating your primary regulator as opposed to your secondary regulator, go to:

"Donate Which Regulator?"

For further information about regulators which are to be used on decompression/stage cylinders, please see:

Which Decompression/Stage Cylinder?

The following site has a series of pages explaining how that particular site's author services his Apeks regulators. This may be of use but try this at your own risk! See:

http://www.deeperstuff.com/apeks-1st.htm

(The site is currently offline but it may be worth a try in case it is back up.)

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Recommendations There are two types of regulator, which can be easily recommended, and there is little to distinguish one from the other, the first is likely to be the cheaper of the two, with the same functionality: The first is the "Apeks TX50" on a 7-foot (2.10 metre) hose using an DIN fit "DS4" first stage with a "TX50" back-up regulator on a 25" (64cm) hose; both with standard bore regulator hoses. This is a tried and tested mid-range Regulator and a non-turret design First Stage...It normally comes with a turret design but the DS4 is cheaper and just as functional The second is a DIN fit "Scubapro Mark 25 G250" on a 7-foot (2.10 metre) hose with a "Scubapro R380" backup regulator on a 23" (58cm) hose. This is much the same as the above, but more expensive to buy and service. The Mark 25 First Stage incorporates a swivel but the end port can make hose routing for single cylinders neater than might otherwise be the case. Scubapro G250's are not actively advertised by Scubapro Europe, but can still be ordered from your local dive shop. A cheaper budget alternative to these is shown below: The "Apeks TX40" on a 7-foot (2.10 metre) hose using a DIN fit "DS4" first stage with a "TX40" back-up regulator on a 25" hose; both with standard bore regulator hoses. This model is basically the same as the first option but it excludes an adjuster on the side of the regulator, which is used to change the breathing resistance.   "Apeks has introduced their newer "ATX" series of regulators. These are slightly smaller than the older "TX" models, but virtually the same - they even use the same service kits! Whilst it might be claimed that the "TX" series has been tried and tested in anger over a longer period of time (and this is very true), it is unlikely that there would be any real performance difference in the sport or intermediate trimix diving ranges. The DS4 first stage will be cheaper than the one which comes as standard with this range and you could specify this if you choose. Back To Top Tips Does the DIN fit First Stage come with a DIN to A-clamp adaptor? If not it is always worth buying one in case you should need to use an A-clamp pillar valve, it can be an essential tool whilst holidaying overseas. If you already own or should choose an A-clamp or Yoke type First Stage, it may be worth buying some DIN Inserts (with the relevant sized allen key). These can be inserted into DIN type Pillar Valves, allowing you to use them. Use hose protectors on hoses which are subject to strain at the end which is connected to the first stage, but only those hoses which are subject to strain. This will help to minimize wear on the hose, where needed, but much like cylinder boots and contents gauge boots they can encourage the built up of grit, grime and salt crystals unless you remove them regularly to clean beneath them. So if you don't need one, don't get one. Buy yourself a sturdy/padded small bag just for your regulator. This will substantially reduce the abuse it will be subjected to, compared with throwing it in with the rest of your dive gear.

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