How many of you use an inline cutoff switch to your 2nd stage?

[BabyDuck]

I used one on my dry suit line for a while, because we couldn't find another intake valve, but that's it.

 

[flots am]

I have a Sherwood SR-1 and I just about will never dive in cold water since I live in the tropics but I was wondering whether it'd be useful to have an inline cutoff switch to my primary 2nd stage just in case I get a freeflow problem when I'm halfway through the tank and am still in 25 - 30 metres down.

What I was thinking of doing in such a situation would be to cut off the air to the primary 2nd stage, switch to my octopus and make a slow ascent with the usual 5 minutes at 5 metres stop instead of rushing up since I'd be pretty low on air by then.

It's completely useless and could potentially kill you or your buddy if someone grabs it expecting to breathe and discovers that no air is coming out.

Cold water free-flows are caused by ice forming in the first stage, which causes it to jam open, increasing the intermediate pressure to the second stage to far above what the second stage was designed for. This causes the second stage to vent air (free-flow).

If you add a shutoff to your second stage, all that will happen is that your other second stage will free-flow. If you add a shutoff to your backup second stage also, what will happen is that one of your LP hoses will explode.

On a no-deco dive, the easiest and safest solution is to continue breathing, and surface safely with your buddy, sharing air if necessary (if you run out).

On a decompression dive with doubles, divers will turn off the tank valve to the first stage that's freeflowing, and breathe off the other one while it thaws, however this is just a band-aid, since if one is free-flowing, switching to the other reg will likely cause a free-flow there too.

The real solution is that if you're going to do deco dives in cold water, make sure you have regs that are designed for it.

Warm water freeflows are usually maintenance problems, but the solution on a no deco dive would be the same: surface with your buddy.

flots.

 

[DivemasterDennis]

I had never considered a shut off, and have never seen one used in a recreational diver's equipment set up. Because of the insightful responses above, now I know why. Thanks all.
DivemasterDennis

 

[drbill]

I must be doing something right (perhaps just buying the right regs?) because I can't remember the last time I had a free flowing reg... and I'm terrible about diving old equipment without regular servicing. I do see free flows at the dive park with some frequency, so I realize it can be a problem, but my regs (Mk10/G250s for the most part) just don't seem to know how to do this.

 

[flots am]

I must be doing something right (perhaps just buying the right regs?) because I can't remember the last time I had a free flowing reg... and I'm terrible about diving old equipment without regular servicing. I do see free flows at the dive park with some frequency, so I realize it can be a problem, but my regs (Mk10/G250s for the most part) just don't seem to know how to do this.

You probably rinse your gear and don't drag it through the sand and diirt.

flots.

 

[Progen]

Thanks for helping me save some money, everyone.

 

[halocline]

So what's happening is that something's busted at the 1st stage and sending too high a pressure to the 2nd stage and the diaphragm there opens up?

Yes, except it's not the 2nd stage diaphragm that opens, it's the valve itself. The first stage accepts tank pressure, reduces it to intermediate pressure (about 140PSI give or take) and sends that to the 2nd stages. 1st stage failure, including freezing, usually involves the 1st stage not being able to hold back the tank pressure, and the IP sent to the 2nd stages spikes. If you were to install a cut-off valve inline, and you actually had to use it, it's very likely that the LP hose would soon burst as it's not designed to take high pressure. Then you'd have a mess, wouldn't you?

Interestingly, the sherwood SR1 is one of the creepiest 1st stages I've ever seen (creep being IP creep) and if you're looking for a good way to spend some money, replace it with a more reliable regulator. Sherwood really screwed the pooch on that one.

 

[tflaris]

I would think that is just adding another point for failure.

And another step to remember if donating that reg to OOA Diver.


Sent from my iPad using Tapatalk

 

[axxel57]

Interestingly, the sherwood SR1 is one of the creepiest 1st stages I've ever seen (creep being IP creep) and if you're looking for a good way to spend some money, replace it with a more reliable regulator. Sherwood really screwed the pooch on that one.

Sherwood has the SR1 not even in their 2013 cataloge anymore, I think they know why.

 

[j2s]

Use them on my doubles set-ups [on the primary and secondary ]for cave diving.........