First stage and Valve drills

[CompuDude]

Consider this: You're shutting off the valve. You're NOT bleeding the pressure out of the system. For the minute it takes to do a valve drill, the regs will be fine, and remain pressurized throughout the exercise. It may seem counter-intuitive, but WAY too many tech divers do it on a regular basis for there to be cause for concern. Those guys would definitely notice if it was messing up their regs, esp. since many do a valve drill at the beginning of each dive, especially during training. We'd have seen a massive flood of messed up regs if it was an issue.

[cummings66]

How does the reg remain pressurised when you breathe them down, i.e. breath until you can't get air before switching? I know many technical divers who were taught to do that. That sounds like it's bleeding the pressure out of the system.

[Sawatdee]

I use Apeks ATX200 andIlike it a lot. I do a lot of valve drills with it and I never had any problem. I think the key is not to press the purge button when it is shuted down.

[CompuDude]

Originally Posted by cummings66

How does the reg remain pressurised when you breathe them down, i.e. breath until you can't get air before switching? I know many technical divers who were taught to do that. That sounds like it's bleeding the pressure out of the system.

I'm not familiar with that technique, although I haven't gone through tech 1 either. What's the purpose? Is this something they do only in an emergency or as part of an everyday valve drill?

Any way you shake it, though, there's a big difference between DIN regs screwed into an isolation manifold and yoke regs hooked up to a single Al.80. I don't think water is going to get past the threads AND the oring to get into the first stage. IF any water gets into the second stage hose, I would think it would be blown out as soon as the air comes back on.

[medic001918]

Cummings, check your PM's. I might be able to help you out with the H valves. I have a couple if they're what you're looking for. Photos are available if you want me to take some.
<DIV>
Shane</DIV>

[cummings66]

Originally Posted by CompuDude

I'm not familiar with that technique, although I haven't gone through tech 1 either. What's the purpose? Is this something they do only in an emergency or as part of an everyday valve drill?

<DIV></DIV>
<DIV>Every technical diver I've talked to says their valve drills always involve breathing the reg down. You close off the post and breathe it down. I forget the exact steps but there was a reason behind doing it that I can't recall.</DIV>
<DIV></DIV>
<DIV>So in my case with the sherwood air bleed I'm worried that if I used that first stage and removed pressure water would flow directly into the first stage, there's a hole there you know. That hole is normally burping air out, remove the air and now with no pressure it's just a hole waiting for water to come in. That's kind of how I'm looking at it.</DIV>
<DIV></DIV>
<DIV>Now it may never be an issue because by the time I do the course I hope to have dual DS4's, but just in case I do wonder.</DIV>

[texdiveguy]

You will not mess your regs up doing s-drills and 'breathing down' your reg for a few seconds...don't WORRY!!

[Kimmie]

In doing valve drills, I was taught to close down the valve after switching to the other reg...I was never taught to breathe the offending reg down before switching

[cummings66]

Interesting, was your valve drill training part of a tech course ora course on divingdoubles?
<DIV></DIV>
<DIV>The buddies I dive with are Trimix divers and that's how they were taught, I'll shoot an email to one of them and ask why they told him to breathe it down. Their training agencies range from DSAT, TDI and IANTD andusually from more than one of them. Of course it could just be the instructors as well. Kind of like how the one I want to go with requires skills I consider super human, in other words beyond the printed requirements.</DIV>

[texdiveguy]

Just one of the reasons for breathing down the 'effected valves' reg is to ensure you have fully closed off that valve.