July 1997
The shape of things to come?
We only dive for the fun of it, so why should a leisure diver need a full-face mask like the Ocean Reef (left)? John Bantin considers the claims made for an item that lets you yell at your buddy underwater
Full-face masks have long been used by professional divers, who cannot usually choose where they dive. They often need protection from water polluted by chemicals or organic waste, such as that found in docks and canals. The expanded air space also allows communications equipment to be installed - essential for working divers who may need to be directed from the surface.
Some technical divers are now adopting full-face masks in combination with gas-switching blocks so that they do not need to remove a mouthpiece and replace it with another during a dive. Others stress the advantages of not having any part of the face in contact with cold water or the fact that there is no jaw fatigue - something I've never encountered!
I tried the Ocean Reef Full-Face Mask, which came supplied with an Enterprise TR94 regulator from the same manufacturer. Naturally it can be used with other regulators too.
It comprises an oval mask with the contours of a familiar scuba mask let in to it, and an internal breathing bib. A broad skirt makes a seal, and six straps hold it tightly to the head. Two dangling balls help the diver identify the lower straps, which might need tightening under water. There are two orifices for attaching ordinary open-circuit scuba regulator second stages. Naturally you can breathe only off one; so if you use a gas-switching block, or indeed are breathing from a single supply, one orifice is blanked off. If you use two regulators, you must be able to turn on and off the supply to each at any time during the dive. A third orifice allows the transmitter of an underwater communications system to be installed.
Because the interior dimensions of the second stage are dramatically increased, I found the regulator free-flowed unless I screwed down fully the breathing-resistance adjustment knob and also switched the venturi adjustment to its minus setting. I also found it helped to use the side port rather than the forward-facing port. This enabled me to use my camera, which was otherwise impossible to get near my eye with the regulator sticking out in front.
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Left: side view of the Ocean Reef
full-face mask, showing connection for open-circuit scuba second stage. |
The internal dimensions of the mask do, however, allow divers to yell at each other underwater. Remember, there is no mouthpiece to clench between your teeth.
How do you clear your ears? The mask has two round nylon blocks between which you jam your nose. These can be adjusted with a screwdriver to suit your face.
Instead of trying the Ocean Reef in suitably murky water, I cheated. Having first made sure I could use the mask in a swimming-pool, I set off to the Red Sea.
Using the mask in circumstances where I could as easily have used conventional gear put things in perspective for me. I found it inordinately uncomfortable and it certainly was not easy to remove it at depth in order to revert to a normal mask and regulator!
The problem seemed to stem from the effects of a current or from swimming about. The internal dimensions of the mask gave rise to a lot of buoyancy, and it tended to lift off my chin and flood unless I had the bottom straps done up exceedingly tightly. (The mask is cleared with air obtained by pressing the purge valve of the regulator.)
If I ever have to dive in polluted conditions, I will put up with this sort of discomfort. I imagine that some divers will also like the positive benefit obtained in exceedingly cold water by using this mask. But personally, in the cold, I would prefer an ordinary mask and a rebreather every time.
It is also my belief that no leisure diver should be putting himself in circumstances where a full-face mask is really needed. We only dive for fun when all is said and done.
One last and important word. Another diver took pains to explain to me that he could dive deep (beyond 66m) on air because he used a full-face mask. His theory was that he could sustain the effects of an oxygen hit (similar to an epileptic fit) without drowning (due to the loss of a conventional mouthpiece). He then thought a full-face mask would allow him to recover and be able to continue the dive!
This is dangerous talk. I do not believe that this is valid reason to use a full-face mask. The seal is not that good and the continuing descent during a fit would only compound the problems of O2 toxicity. However, this is not to say that in-water recompression has not been successfully achieved using 100 per cent O2, a fixed position for the diver, a full-face mask and an attendant nurse.
The Ocean Reef Full-Face Mask costs £299.
Ocean Reef UK, 0181 399 7049
Colour conscious
Many regulators available today are compatible for use with nitrox at less than 40 per cent O2, but some now appearing on the market are dedicated to nitrox. That is to say they bear a colour code designed to indicate their special nature. This colour code generally seems to be yellow and green, although in Germany the official colour is blue.
Of course, buying a yellow and green (or blue) regulator does not necessarily mean much. Some are suitable for O2 only to low percentages, whereas others are up to a full O2 specification. Furthermore, once a "nitrox" regulator has been used with an ordinary scuba cylinder of air, it loses its O2-clean rating.
Apeks now sells both its TX40 and TX50 regulators in nitrox-dedicated colours, assembled from components suitable fo use with O2, and put together in an O2-clean (J) room. O-rings are made from Viton, the filter in both regulators is bronze, and O2-compatible lubricants are used throughout. The standard is so high that, fresh from its packaging, a Nitrox TX40 or Nitrox TX50 can be used with pure O2.
However, due to its inability to control the quality of gas that may be used by the buyer, Apeks clearly cannot guarantee these regulators with nitrox mixes richer than nitrox 40.
The Apeks TX40 with venturi control switch and the TX50 with the additional breathing-resistance control knob have, in the past, surprised us with their incredible beat-the-machine performances during Diver Magazine comparative tests. No wonder, then, that they have become favourites with many technical divers.
Their environmentally dry-sealed diaphragm design features two hp ports in the main body of the first stage and four mp ports mounted on a low-profile turret that can be used the right way up without striking the user on the back of the head during a dive.
The specialist needs of a diving reporter have resulted in what is rapidly becoming known among some tekkies as a "Bantin rig". I often use twin independent cylinders, one with air and one with, say, nitrox 36. I use air for the deepest part of my dive, then swap to nitrox on the way up as soon as it is safe to do so. Although spending much of the dive breathing nitrox, I use an air deco program.
I found the Apeks Nitrox TX regulators ideal for my purpose during these "extended-range nitrox" dives and always up to the same standard as my much more expensive air regulator.
The Apeks Nitrox TX40 costs £239 and the Nitrox TX50 costs £294.
Apeks Marine Equipment, 01254 692200
Don't laugh...
In line with common practice among other BC manufacturers worldwide, AP Valves, the manufacturer of the ever-popular Buddy Profile jackets, has added the pull-dump feature (left) to the corrugated hoses of all its Profile BCs.
This does not mean that you lose the other familiar
AP Valves pull-cord dump valve on the right shoulder. It is an "as well as" not an "instead of".
When you want to release air during an ascent, you operate the pull-dump by simply tugging the direct feed and corrugated hose in the normal way. I found that this system worked as well as that of any competitor, but when I took it apart in front of an audience of experienced international divers there were some attempts at ridicule.
AP Valves has chosen to connect the dump valve to the business end of the corrugated hose with an internal cord, rather than the more usual stainless steel wire. Some referred to "a British manufacturer using bits of string". Whether or not they have a point remains to be seen.
Buddy Profile jackets cost from £342.
AP Valves, 01326 561040
Thinking small
A mechanical pressure gauge at the end of a long hose may be standard kit but it is not always appropriate. Divers with air-integrated computers and tekkies with sling tanks usually find such gauges unnecessary.
The Apeks Mini Pressure Gauge is a button-sized device without a hose which screws directly into the spare hp port of the regulator.
Small though it is, I found it easy to read, and it was nice to be able to confirm a cylinder's pressure without having to fire up my air-integrated Aladin with the inevitable delay. I found I could also check for a steady gauge during initial inhalations, to prove all was well before I entered the water. If you use an air-integrated dive computer, I suggest that one of these is indispensable.
Hung with equipment as one is for a technical dive, it was especially nice to do away with big traditional pressure gauges on deco cylinders, and the Apeks mini gauge proved easily readable during the decompression part of the dive. It reads up to 350 bar and costs £26.
Apeks Marine Equipment, 01254 692200
Analysing oxygen
WHEN David Tracy took a nitrox diver course, he did not like the oxygen analysers he found himself using. So, being a bit of an expert on the subject, he decided to design his own. The Alpha-1 Oxygen Analyser is the result of his endeavours.
Primarily, David attended to the sensor and electronics, which are often not temperature-stable. The very act of allowing a gas to flow over a surface can cool it. The sensor and electronics of the Alpha-1 are stable between -20C to +50C. In addition, it has a linear output response over the range 0 to 100 per cent O2, so you can calibrate at one point and it will be accurate throughout.
The sensor will last around two years, but this period is extended by the use of a simple screw-on sealing cap. I liked the idea of having an alternative place on the unit on which to screw this, so that when off the sensor port it does not get lost.
The small case is made of anodised aluminium, sealed against the ingress of water. The on/off switch and calibration control are robustly made to what looks like a military spec. A large stainless steel eyebolt allows the unit to be hung on a hook either during storage or while in use. Power comes from a PP3 battery.
Sensors must not be over-pressurised and this unit employs a method of sampling that, currently, is probably unique. The unit is linked via a clear plastic hose and a suitable flow-restricting connector (specified when ordering) to the medium-pressure supply from your regulator. This is normally the one that feeds your BC.
Your regulator first stage is therefore employed as a flow-control valve. Instead of holding the unit over a cylinder valve cracked open to an undetermined degree, the gas flow is accurately controlled. And instead of vaguely waving the unit around in the air to calibrate at 20.9 per cent O2, you can connect the unit first to a cylinder of air.
I took the Alpha-1 to Hurghada in May at the time of the TDI conference, and it proved so popular with delegates who were diving there that it was at serious risk of going missing!
What drawbacks did I find? Putting my regulator with all its peripheral hoses on to a cylinder of air to calibrate the Alpha-1 meant that there was a lot of residual air left in it when I transferred it to a cylinder of nitrox. This meant that although the sensor has a response time of less than 40 seconds, it took a long time before the nitrox started to come through. That is because the controlled flow-rate is so low.
Because I was using nitrox in both my main rig and sling-tank, I decided that what I needed was another rig for calibrating. I therefore connected the Alpha-1 to someone else's aqualung, which was set up ready to go diving. To my horror, during the process of calibrating for air I saw water passing down the clear plastic hose. This was not the fault of the Alpha-1 but of the regulator to which I had helped myself. Someone was used to getting a very wet breathe!
So I did end up waving the unit around in air to calibrate it in the usual way before putting it on to my nitrox-rigged regulator and d/f hose to analyse what was there.
If a shop uses this unit, it can easily have a cylinder of air and a regulator dedicated to calibration.
The Alpha-1 costs £259 with either a flow restrictor to suit your BC or a DIN connector for those who are happy just to "crack open the cylinder valve a little". To help, the DIN connector has a simple over-pressure indicator.
Alpha-1 Control, 53 Percy Road, London, N12 8BT
Appeared in DIVER - July 1997
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