Long hose with full-face mask?

[MikeS]

Thanks for the information and entertaining argument. You’ve helped me think of issues that I hadn’t, that’s what’s great about Scuba Board. I need to reevaluate the idea of getting a FFM as it looks like it creates more problems than it solves.

Mike

 

[cast55]

Looking at the post dates here, this reply may be ridiculously late, but here's my take:

First off, that list of reasons for not using FFMs is entirely valid, and I still stand behind every one of those points.

That said, I still have to use them in some situations, like diving swiftwater, or working dives when I need voice comms, or blackwater dives that don't necessitate wearing a helmet.

When I use them, it may be on surface supply, which in addition to the umbilical requires a bailout bottle. This is connected via a standard DSI bailout valve.

When using a FFM on SCUBA, it is done on the standard DIR rig, with a couple of differences: The FFM is actually connected to the hose which would ordinarily feed the backup reg (around the neck). In this case, that hose will need to be a few inches longer to accomodate turning your head all the way to the left. The FFM feeds from the right like any other second stage, so with the AGAs that come with the showerhead reg with a left side feed, I use a rigid tube 180 degree adapter that makes it feed from the right. The long hose reg is as per normal, except you use a backup (non pneumatically balanced or detuned) second stage instead of a high performance balanced second, and it gets clipped off on the right chest d-ring, just as it would if you were on a stage. In this position, it is ready for donation at all times.

I do not do multiple gas dives while wearing a FFM, or in fact anything other than those dives where the risk of not wearing it outweighs the risk of wearing it. For fun diving, be that recreational or technical, there is no place for these.

-Sean

 

[saturated]

If you want to use the long hose config with a ffm check out the kirby morgan m48. It would eliminate alot of issues raised previously.

 

[TX65]

On the FFM issues, I use one and have been since my diving beginnings as a commercial diver. Why do I use it? I prefer it for many reasons but those are my reasons and may not be yours.

In my rig, I use a DSI manifold block mounted on the right shoulder strap of my harness with two independant 1st stages feeding it. I then run one hose from the manifold block to the 2nd stage on the mask.

This is nothing new, DSI manufactured this block for use with the EXO. It is also an adaptation of the side block on a Superlite helmet so it is a proven system. I prefer this arrangement to a side block on my lightweight mask since I dont want the added weight or hoses up around the mask.

To accomodate gas switching, you install an extra bailout valve (comes with one and a non return valve) and that way you can switch between gases by turning knobs located on you chest. To add a safety margin, the two knobs are different colors.

If you want quick disconnects, you can install them between the mask and manifold block as well as between the 1st stages and the manifold block. Make sure you use good ones like the Hanson stainless units that prevent flow on either hose when disconnected.

Oh, I run an Octo off the block in the event of a 2nd stage failure on the mask or an OOA emergency for others. I also carry a compact mask in a pocket on my BC. In addition, my BC and my drysuit are fed of this block.

Compared to running a 2nd stage and an octo on every tank it is less complex since I only have two 2nd stages vs four 2nd stages with conventional scuba running doubles.

To increase to three tanks, I can either add another valve to the block or can uncouple the tank not in use and couple the new one in with a quick disconnect.

One final comment, if full face masks or helmets were unsafe, they wouldnt be the standard of the commercial diving industry.

 

[cast55]

TX65 once bubbled...

Compared to running a 2nd stage and an octo on every tank it is less complex since I only have two 2nd stages vs four 2nd stages with conventional scuba running doubles.

This statement makes absolutely no sense. A doubles rig has two first stages, and two second stages (1 primary and 1 backup). Also, let's not lose sight of the original discussion, which was regarding the use of full-face masks in SCUBA applications. The DSI block is good gear, but not necessarily the most appropriate setup for SCUBA, especially when doing multiple gas dives. One of the greatest advantages of stage diving is the complete independence of the stage from the rest of your rig, allowing it to be jettisoned at any point during the dive, or handed off to another diver if necessary - actions that are precluded if these gases are connected to a block on your body. Also, by doing these manual gas switches with a half-mask and reg, your buddy is able to tell by visual inspection whether you are on the right gas, and act accordingly. Similarly, if a buddy starts to act a little strange, it is a very simple (and prudent) matter to offer the long hose (bottom gas) to immediately rule that out as a possible problem. When it is not, you go back on the long hose - no big deal. If you are wearing FFMs, any attempt at gas donation requires either a bailout on the part of the distressed diver, or connection and manipulation of the distressed diver's block - complicated enough to make one shy away from donating at the slightest provocation, and time consuming enough that when there really is a problem, you have just allowed time for the situation to go from bad to worse.

As far as safety is concerned, did you happen to read my initial post concerning the risks of FFMs? Sure, FFMs and helmets are the commercial diving standard, but that is in conjunction with other commercial diving standards which do not allow for the sort of diving we are discussing: extended excursion mixed gas dives on self-contained open circuit gear, utilizing completely in-water accelerated decompression on enriched mixtures. As open circuit SCUBA divers, we have issues to consider which are moot in commercial operations.

-Sean

 

[TX65]

As I said in the beginning, I have my reasons for using FFM equipment and my rig.

The point of my post was to describe how I have rigged my system to facilitate switching between gases using a FFM and how I allow for another diver requiring use of my gas.

I typically dive two different Nitrox mixes. One of these is my bottom gas and the other I switch to for any deco stops or just to wash my system out. These mixes may be in 2 tanks or 4 tanks. I do not dive Trimix, nor do I care to (I breathed enough Heliox in my past). Nor do I dives to 350 fsw,,,been there...done that.

As far as the comment that my rig makes no sense, it does.

Lets look at a dive with a set of doubles and a deco tank. I have a 1st stage on each tank just like you do, but instead of having a primary and backup 2nd stage on each 1st stage, I run a single hose from each 1st stage to the manifold block. Each connection has an on/off valve and a Non-Return Valve mounted clearly on my chest where I can see it.

From the manifold block, I run two 2nd stages with one being on the full face mask and another available in case my primary 2nd stage fails or another diver needs to access the same gas I am breathing.

Now, you bring up a point about another diver is next to me using a FFM. First, like a good buddy, I would be sure they have the ability to share gas with a 2nd stage and have a spare mask for themselves if they have to ditch their FFM. I am also prepared with my spare mask to be able to ditch my FFM to share gas with them or another diver.

I could go into if they had a rig like mine, what could be done to couple them, but time is marching on.

I prefer using a full face mask for the range of diving I currently do. I have built my rig to be able to switch gases and I have built-in redundancy for CMA and to allow for a buddy diver in the event they require assistance. I also have accepted the nuiances of possibly ditching my FFM and donning a conventional mask should I need to.

Great thing about sport diving is people are free to apply their knowledge and experience. If everyone only did things one way, we would all be diving Mark V helmets and Scuba wouldnt even be around.

 

[BigJetDriver]

TX65 once bubbled...
On the FFM issues, I use one and have been since my diving beginnings as a commercial diver. Why do I use it? I prefer it for many reasons but those are my reasons and may not be yours.
One final comment, if full face masks or helmets were unsafe, they wouldnt be the standard of the commercial diving industry.

I've been using the Divator MkII, and the EXO 26 for many years now and have found them to be very safe and useful. My all-time favorite has become the Widolf, as resurrected by Tracy Robinette of Divematics. I use it with my Extended Range Mixed-Gas Inspiration so that I can utilize a long-range through-water OTS comm unit. Damn, is that mask comfortable, even with the installed DSV block and APEKS second stage!

As Bob3 once asked: "How's a guy supposed to take a nap without an FFM?" Of course, I'd have to ask how a guy is supposed to get a nap with all those bubbles roaring around his head anyway,eh?

=-)

 

[mntdiver]

Tell me how many people have ever been harmed by diving a full face mask when properly trained. There have been far more that are still alive because they were wearing one then have ever been hurt because of wearing one. Add communications and the safety factor goes up exponentally.

Go unconscious for whatever reason wearing your DIR rig and I hope you said good bye to your loved ones...