Divator MK II (AGA) report

[DA Aquamaster]

I've got a question about using a full face mask. Do you carry a normal octo for alternate air source ? Do you have a standard scuba mask in case you have to remove the full face ? How hard is it to switch to an alternate air source ?

It scares me when I see FFM divers without a backup mask, and I do see a lot of them.

Most intelligent FFM divers will carry a normal mask either tucked in a pocket or worn on the back of the neck to switch to in the event their primary regulator fails, runs out of gas, etc. For technical divers this is also done to allow a switch to one or more deco mixes during the dive.

Some divers use a gas switching block to switch from one gas source to another whether it is a stage bottle, deco bottle or bailout bottle (used with surface supplied diving). If using different gases, great care has to be taken not to get it wrong during the switch. A gas switching block essentially leaves you with only the second stage mounted on the mask and this still leaves you vulnerable to a second stage failure. It is however extremely rare to have a second stage fail in a manner that results in a failure to deliver gas.

A gas switching block also does not help your buddy if he or she is OOA so some type of octo is still required to allow you to share gas with your OOA buddy.

I use a Kirby Morgan M48 FFM with uses a detachable pod in the lower half of the mask. This approach allows you to switch to an alternate second stage of any type without having to remove and replace your mask. It also enables you to hand off the pod as a donated second stage as it has a regular mouthpiece in it that you can breathe off like any other second stage. This allows a normal long hose and bungeed backup configuration to be used without the need for an extra mask. It makes a lot of sense in technical diving as it makes switching gases a non event and if you need to maintain com capability through the whole dive, you can fit the deco regs with pods as well.

 

[ralawrence]

None of my diving puts me in a situation where I cannot reach a surface (no caves/submerged ships or the like). I have found the SAR TEK gas switch (around $400 for harness mount etc) works. One moving part (not much to fail and I love KISS). I use a 13 cubic foot bail-out bottle whether I am on surface supplied hose or tank. Have not needed it so far. I often dive single (commercial) inspecting drinking water reservoirs and the like, so an octo will not do much good if the tank supply or surface hose fails. Need independent supply to get up safely.

Russ

 

[james croft]

I would recommend a Kirby Morgan block for switching gas. It is made out of brass and is bulletproof. I have not used the Sartek block but I know some guys that have and I was told that it had a Delrin component in it that can be scored by sand and as a result caused leaks. You will never have a problem with the KM block. It is also cheaper than a $400 Sartek.

 

[DA Aquamaster]

It's not a configuration I would reccomned for the average diver, but given the combination of commerial, solo and technical diving I do, I use an Oxycheq gas switching block with my Kirby Morgan M48. It allows flexibility in terms of using surface supplied gas and a bailout and also allows easy switching between independent doubles with a FFM on rec/tech dives. The M48's pod design still allows access to deco gases through conventional regulators as well as "normal" gas sharing off a buddy's octo. I am not a big fan of accessing different high O2 mixes through a gas switching block - it has too much potential to kill you if the block is inadvertantly switched at depth.

I considered the Sartek, Kirby-Morgan and Oxycheq switching blocks and went with the Oxycheq due to it's solid construction and simple, non confusing and basically idiot proof design. The design is harness mounted and it is very easy to feel exactly how the valve is switched which is a very important consideration.

I share the same concern indicated above about the delrin parts of the Sartek and agree that the $400 price tag is about $100 more than a more durable solid brass switch block. The KM is also a good block, but is not readily available unless you have a KM dealer handy.

One thing to consider with a gas switching block is what you have attached to the first stages in question. If your configuration has the potential to create a situation where the block can isolate a first stage from any second stage you need to add an overpressure relief valve to the first stage.

For example, if you are diving with a primary tank, are breathing off the primary tank and the pony is not connected to any second stage, a slight IP creep over time could result in enough pressure in the hose to burst the hose and vent all of the pony's gas supply.

Alternatively, if you were diving in cold water with the same configuration, your primary regulator "freeze flowed" and you switched to the pony, if the gas block then isolated the frozen freeflowing first stage from any means of venting the excess pressure the odds are very good that you would almost immediately burst the LP hose between the first stage and the gas block.

OMS first stage OPV's are about $19.00 on Leisure pro, but the same OPV has a dealer cost of something like $3.65 from Trident, so you could probably get one for around $10.00 from almost any honest LDS. It's a lot cheaper than a new hose and adds a needed level of safety.

 

[Steve from NZ]

I ended up gluing some neoprene to the nose block and it worked a treat - equalising as easily as a regular mask but with full face comfort! Thanks for the tip.

Steve

 

[kwinter]

I used to use the Kirby Morgan manifold block, but I went with a strange and unique configuration. If anyone wants to buy my KM block, PM me. For that matter, I also have 2 extra AGA masks in great condition. One with buddy phone and the other with the hard-wire EMA2.

I wanted a manifold block, not just a gas switching block. The Oxycheq is great, but I think they missed the boat by not putting additional outlets in it. So I modified a simple, inexpensive manifold block by putting two shutoff valves in with quick disconnect fittings. It's not as simple as turning the single valve 180 degrees, but it does the trick. Running off the block are my AGA 2nd stage hose, my inflator hose, and my drysuit hose. I could also run my 7 foot hose that is my alternate, but I choose to run that directly off the right post. The Oxycheq block would be perfect if it had a couple more outlets. The Kirby Morgan manifold was great, but when I decided to go with the QD fittings, it was easier to make the change and I figured it would sell well with one of the extra masks.

Ken

 

[ProfessorAronnax]

After lots of helpful advice (thank you all for your patience during my quest) I got an AGA. I planned to use it for water reservoir inspection, so of course the first use has been installing steel walls on the front of a river water intake structure down stream of Mt St. Helens. And to do that, about 3 to 4 feet of clean coarse sand had to be blown away. This involved using compressed air and took hours to accomplish. Moved about 100 cubic yards of sand.

During this time I was super innundated by sand etc. The AGA worked like a champ.

I purchased the AGA with the ABV-1 and both mask and surface wireless communications units (buddy phone) from OTS.

The ABV-1 worked great and did not leak inspite of being drenched with sand and rapidly moving from below to above sand laden water (working in about 7 feet of water once sand gone, started with 4 feet). The passage from the ABV and regulator supplied air was seamless. Maintenance consisted of removing a philips screw, unscrewing the ABV cover, rinsing and re-assempling. A snap to do. Did not need to close ABV each time I went under. However, I plan to close it when I dive deeper than 6 feet.

The communications worked well after we figured out how to adjust for the ambient noise when I was using compressed air to blow sand. I am allergic to neoprene and must wear a latex hood under my 6 mil neoprene hood. While I had to listen carefully to understand what was being said, I always knew when someone wanted to talk to me. No modification to the hood/underhood necessary.

Perhaps the best part was air temp in 60's, water around 50 and mask NEVER fogged regardless of air source. If you are considering a FFM and want to hear more, give me a shout.

Russ

Congratulations on your purchase! You certainly bought the right mask for the job!