Modular valve failure point question

[Bierstadt]

Hi,
Is the isolator valve post on a modular valve a meaningful failure point when used in single tank configuration? I am converting to DIN with tech and doubles in mind in the future and would like to know if the different gas routing of a modular valve compared to a conventional DIN valve is significant. I am fine with the other tradeoffs.
Thanks.

 

[divad]

Hi,
Is the isolator valve post on a modular valve a meaningful failure point when used in single tank configuration? I am converting to DIN with tech and doubles in mind in the future and would like to know if the different gas routing of a modular valve compared to a conventional DIN valve is significant. I am fine with the other tradeoffs.
Thanks.

What are the "other trade offs"?

 

[tbone1004]

it's 2 or 3 static o-rings, so no.

there are no tradeoffs to going with that valve unless you have 2 tanks with a lefty/righty valve in which case one of the valves is weird to shut off since it is on the wrong side, with the HUGE added advantage of that post making it much more comfortable to carry

 

[decompression]

if you are ok with Orings and plugs in your first stage then there is no more risk in a mod valve.

 

[Bierstadt]

Thanks guys, question definitely answered.

@divad Mostly increased weight, also sometimes cost, and added potential complexity due to the existence of left and right-handed valves.

 

[tbone1004]

@Bierstadt have you weighed the valves? I don't think they're that much heavier, maybe an eighth of a pound?
on the cost side, the Thermo's do get considerably more expensive, but DGX is getting them from the same supplier and they are the same price
Only complexity bump is a pair of static o-rings once it is installed, so not really an issue. I haven't seen or heard of those failing on a plugged valve. Have with a manifold, but it's usually when they get rotated with insufficient lube or knocked

 

[divad]

@divad Mostly increased weight, also sometimes cost, and added potential complexity due to the existence of left and right-handed valves.

Oh, you mean't doubles valves without isolator on single tanks. Do drills with both. You'll remember that, if you are staring at the knob end (at the nut) of either the Riight valve or Left valve, they both turn the same way R tight/L loose.

 

[divad]

To clarify, if you shut down the left-side modular valve on a single tank a few times under water, you'll start to remember which way is open and which way is closed.

 

[Bierstadt]

@tbone1004 I only have handled the DGX modular valve; it may not be much heavier than a DGX standard valve, but there is is always going to be a bit more metal in a modular valve than a standard. I have seen videos of the ISE guys sending used stage bottles floating to the surface for retrieval and they mention that heavy first stages (and presumably valves) can cause negative buoyancy. Obviously one must always match one's tools to the task, and valve weight can be unimportant or critical. Just one more thing to keep in mind.
Extra question if you don't mind, though; how do you feel regarding thermos vs DGX modular valves? You mention that they are made by the same people, but I have read that thermos turn smoother. For more than twice the price they certainly ought to. I bought the DGX valve to get some hands on experience with modular valves, but seeing as it is going on my pony it will never be part of a doubles rig. Well, maybe a very small doubles rig... for scuba dogs or something... xD

@divad As you say, a bit of training and practice easily addresses the right/left complication. It does not address a helpful buddy accidentally turning off one's air because they are confounded by the existence of non-standard valves. That is the main risk my forum reading/research indicated. I would consider it a minor risk, but still one to be aware of if one has a left valve on a single.

 

[tbone1004]

@Bierstadt @victorzamora has several of the DGX valves, and my new thermos say made in Taiwan. They are almost indistinguishable so I can't imagine any difference in where they are made. His turned quite smooth so I wouldn't have an issue with it.

I prefer the extra stud on the end of the modulars because it makes handling easy and there really isn't any real use for launching bottles to the surface. If they are empty, the modular valves will still float up, AL80's are over 4lbs positive when empty....

regarding your buddy, one of your pre-dive checks right before you jump in or descend should be verifying that the valve is all the way open...