Gas Switching Protocols

[Bismark]

regarding the "n" as in Name on Tank its really more of a double check that you really picked up the tank you intended to. Although at that point in the dive its a bit moot. and frankly, if the MOD is correct go ahead and breath it. from my perspective, if I've been so careless that I picked up the wrong tank on the dock/boat whatever and only notice it at the switch perhaps I'm in the wrong hobby

maybe they came up with a cool mnemonic and needed an "n"

Yep, "otox" sounds too much like "botox"....................

 

[ageddiver]

For me... Normally the last stop of a gas (e.g. 30ft for 50%) is done on backgas. There is little benefit to a deco gas at that portion in its usage and the break serves to both reset your O2 clocking a little and provide a time to stow the old deco reg before deploying the new at the next stop. Its not necessary to double this stop to "stay on deco schedule". Then again, my deco probably has less time at 30ft on 50% than most.

ps thank for the reminder about purging. I do that too, just forget all about it in the retelling.

I'm not sure I understand the logic in this. While you might be able to get by with this on "shallow" dives, isn't it a very bad habit for deeper dives? Going back on a 18/40 backgas (or a 16/50) instead of breathing 50% at 30ft. is not a good plan. You may very well have a schedule that lets you do this now, but sometimes it's hard to break a habit like that.

To the OP, the best method is to simply turn on only one gas at a time after visually verifying that the knob you're turning is on the correct bottle (markings). Keeping mixes in the same positions every dive and using different second stages (or different mouthpieces) on each are tricks to give tactile cues should vis or light not be available.

 

[Bismark]

I'm not sure I understand the logic in this. While you might be able to get by with this on "shallow" dives, isn't it a very bad habit for deeper dives? Going back on a 18/40 backgas (or a 16/50) instead of breathing 50% at 30ft. is not a good plan. You may very well have a schedule that lets you do this now, but sometimes it's hard to break a habit like that.

To the OP, the best method is to simply turn on only one gas at a time after visually verifying that the knob you're turning is on the correct bottle (markings). Keeping mixes in the same positions every dive and using different second stages (or different mouthpieces) on each are tricks to give tactile cues should vis or light not be available.

This should be good..... I'm going to take out my Batphone and call Jeff......

 

[texdiveguy]

Even though each of my deco regulators does have a different brand/model of second stage (not by design, but driven by economics and availability), I don't rely on that as ID for differing gases. But all them have the same DR black mouthpiece as it is the most comfy for me.

I do use a trick I find helpful only to 'me' as a method of gas MOD verification. On all my second stages exhaust diverters ( I place a small 3/4" long strip of waterproof surgical tape) on which I print with a black Sharpie the MOD of that regs gas. I use this in addition to standard gas swap protocols to verify the reg. is the correct one. Works for me.

 

[DA Aquamaster]

One addition - I use a comfobite mouthpiece the rich deco gas as it feels very distinct in both your hand and mouth and verifies even in no viz conditions you have the O2 or high percentage deco mix.

So between properly stacking two deco bottles (assuming an offshore dive) and following the hose to the reg with the comfobite mouth piece a diver can still make a gas switch in the dark or in no viz.

I also mark the MOD on the left side of the bottle near the bottom so it can be seen by a buddy and on the right side just under the shoulder where the MOD can be seen by me.

One difference - I have my deco bottles set up with the handle facing down and the reg facing toward the right. What is the reasoning for having the handles face to the left?

 

[texdiveguy]

One difference - I have my deco bottles set up with the handle facing down and the reg facing toward the right. What is the reasoning for having the handles face to the left?

A bit easier to reach and turn with the left hand when bottles are slung from the left side for many divers.

I prefer to L / R sling multi bottles myself.

Has never been an issue for me to operate the deco bottle valve handle whether it is on the left or right of the valve. I have never rigged a handle to face downwards.

 

[battles2a5]

One difference - I have my deco bottles set up with the handle facing down and the reg facing toward the right. What is the reasoning for having the handles face to the left?

It keeps the hoses and second stages up and out of the way. I route my hoses down right next to the stage strap and tuck the second stage in as close as possible, so they don't get crushed between the bottles and don't stick out anywhere that can get snagged. You are probably achieving the same thing with your set-up, assuming you are routing things to the left of your stage strap.

 

[Rick Inman]

Going back on a 18/40 backgas (or a 16/50) instead of breathing 50% at 30ft. is not a good plan.

Tell me why it is bad to switch to backgas (say, 18/45) for the last minute of your 30' stop as you transition to 20' and move to O2.

 

[texdiveguy]

Tell me why it is bad to switch to backgas (say, 18/45) for the last minute of your 30' stop as you transition to 20' and move to O2.

I to have my note pad and pencil ready.

 

[Flightlead]

To the OP, the best method is to simply turn on only one gas at a time after visually verifying that the knob you're turning is on the correct bottle (markings). Keeping mixes in the same positions every dive and using different second stages (or different mouthpieces) on each are tricks to give tactile cues should vis or light not be available.

yes I always keep the richer mix to the right of the lighter mix, even when laying my tanks down on the ground or by the dock. I also use a reg with a bright yellow cover for my 100% bottle and a green valve knob on that tank. however I hate to rely on "tricks" like this. it would be easy to be in a hurry and put the wrong reg on the bottle, or perhaps the fills get mixed up and the green knob ends up on the lighter mix. that could easily lead to an error train.