Question Breathing the hose dry (during valve drills) - Risks with water entry into first stage?

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Murre

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Hello,

People always say that you shouldn't submerge an unpressurized regulator (first and/or second stage) for soaking after dives, and that it should be attached to a cylinder and be pressurized..

But still, the majority of technical divers regularly do valve drills, including myself. That means breathing the hose dry before switching to backup and so on. During this sucking the hose dry-moment, the first stage of course becomes unpressurized, and most often the first stage becomes a little loose on the valve (meaning it shouldn't be able to safely form av protecting seal at depth during that moment?)

Could somebody explain to me the risks and effects to the first stage during above?

Thank you
 
But still, the majority of technical divers regularly do valve drills, including myself. That means breathing the hose dry before switching to backup and so on.
Hmmm. When I was tech diving, I never did this. (Is this something new? Some new approach to BG drills, only?) Seems (to me) a bad idea.

For deco regs, during a dive we would periodically open and close the valves to make sure that these deco regs remained charged.

rx7diver
 
You can feel a difference without completely depressurizing the hose. It's best to stop sucking at that point.

I used to use a Sherwood reg with a dry-bleed first stage for deco, and I accidentally left it in the water overnight (valve off). When I looked at it the next morning, the line had depressurized, and there was definitely water in the 1st stage.
 
Breathing them down was the way we did it on my Fundies course about 5 years ago. I didn't like the idea at the time, and from time to time try and convince myself it's fine. If the first stage isn't knocked during this time and you are at a constant depth I'm pretty sure there won't be water ingress. When you breath it down the lines will will be filled with gas at ambient pressure, even if you hold the purge button this gas is unlikely to escape. If you add a second opening, by knocking the first stage or holding 2 purges then yes it's likely to flood. I guess the pro to breathing down is you know you have correctly fully shut down the post - forming a positive feedback loop for yourself.
 
People always say that you shouldn't submerge an unpressurized regulator (first and/or second stage) for soaking after dives, and that it should be attached to a cylinder and be pressurized..

smh. working in a dive shop and/or dive boat, the 2nd stages need to be “de covid” and/or cleaned which involves soaking the 2nd stages, there could be 50 regs needing disinfecting. you think all those regs are going to be pressurized? Do you think any high traffic dive shop or boat is going to pressurize regs before cleaning? In 10 years not once has a reg had water in it unless someone left the dust cap off the yoke. these regs are serviced yearly.

I personally have 4 regs used for a variety of classes and each reg gets about 100 dives a year on them. they are din and a din cap is used. they are soaked sometimes overnight (too tired) and never once has there been water in the 1st stage in 15years. these are without acd’s. rebuilt every year.

theoretically yes. real world? not unless you’re *shrug*

Now 30 or more feet underwater could be a different story.
 
The inside of most regulators are chromed or otherwise protected from short term exposure to salt/pool water. OTOH when we had to intentionally change regegulators on tanks underwater (long working dive with ears not equalizing easily) it was better to have full tanks dropped to me on a line, swap the gear over on the bottom, and send the empties up. My bottom time for the shallow job exceeded 8 hours without coming up. When we were done all the gear, including the tank valves, were stripped to pins and springs, cleaned and reassembled with new seals before the next day's diving. The excess labor was only about an hour and a half with no resultant long term corrosion problems. The tanks were primarily steel 72s so they stayed negative at all times during the dive, even when striped of all other gear.
BTW back in the dark ages before PADI split the training into 3 sections scuba divers were routinely taught how to breathe off a scuba tank without a regulator, and generally we also learned how to eat and drink underwater. This last bit is handy when rock scallops, spiny oysters or other encrusting oysters are available during a clean water dive.
 
Breathing them down was the way we did it on my Fundies course about 5 years ago. I didn't like the idea at the time, and from time to time try and convince myself it's fine. If the first stage isn't knocked during this time and you are at a constant depth I'm pretty sure there won't be water ingress. When you breath it down the lines will will be filled with gas at ambient pressure, even if you hold the purge button this gas is unlikely to escape. If you add a second opening, by knocking the first stage or holding 2 purges then yes it's likely to flood. I guess the pro to breathing down is you know you have correctly fully shut down the post - forming a positive feedback loop for yourself.
The reason the regulator is depressurized after shutting down the post is so that you can determine where the bubbles are coming from in the event of a failure. If the bubbles stop, you know that you shut down the correct post. If the bubbles continue after the regulator is breathed down, either you you shutdown the wrong post, or you have a failure that requires that you isolate.
 
I suppose in a technical dive environment where a straight away ascent is not possible then shutting down a post and depressurizing a regulator and possible water entry (unlikely) is the least of your concerns. Regulators can be easily serviced, humans not so easily.

For a drill, I think I would simulate that skill thereafter doing it once to verify procedures.

James
 
I entered the water once with a depressurized yoke-regulator on a pony tank. When I tried to pressurize it at about 25ft, the regulator ejected lots of bubbles from the valve area and seemed to not want to pressurize. Presumably, the regulator was flooded, and I simply shut off the tank and figured I'd deal with it after the dive.

I'm not a tech-diver, but I can't imagine a scenario where you'd want to depressurize a regulator completely underwater. Maybe pressurized with the valve closed to prevent free-flow, although you can also get a "switch" that goes between your hose and the 2nd stage to prevent free-flow.
 
I'm not a tech-diver, but I can't imagine a scenario where you'd want to depressurize a regulator completely underwater.
The scenario the OP is referring to is a valve drill where you're hovering at a fixed depth and practicing turning your valves to simulate motions you would go through in an actual failure scenario. It's not a real-dive failure. If it were a real failure, I don't think anyone's first concern is going to be future corrosion.

I believe @Jacob BV explained why it shouldn't be a concern during a valve drill:
If the first stage isn't knocked during this time and you are at a constant depth I'm pretty sure there won't be water ingress.
 
https://www.shearwater.com/products/swift/

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