First stage and Valve drills

[cummings66]

Here's the question I've been pondering.


In technical courses that include valve drills you'll be asked to shut off avalve and breathe down the reg.


I've been told by almost every dive shop I've been to that you never want a first stage to lose pressure under water by shutting off the valve because it will flood and need to be serviced. Not to mention the SPG may be damaged.


What's the truth of the matter? Are there some first stages that won't flood, brands? I am of course assuming that all the first stages we're using are sealed envirionmental types because in the midwest the water is usually cold.

[chrispete]

The system is still sealed, so there's really not much danger of getting water into the 1st stage. It would be possible I suppose if you were to descend while holding the purge button on the second stage with water in the reg.

[scubatexastony]

AND....

In a tech class, you are shutting down one of two first stages (double cylinders) that are usually connected via a manifold with an isolater valve between them.

~tony

ps... wass up! Chris?????

[cummings66]

OK, so let me understand this then. I have a Sherwood Blizzard with an air bleed system that maintains positive pressure to keep it dry.(Probably not the right terms to describe the bubbles that flow from the first stage)I'm thinking that by losing that pressure the little rubber poppit would be pressed in and so seal off the first stage preventing water from coming in?
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<DIV>I'm probably going to get an Apeks DS4 later on and I'm not sure how that sealed system is designed.</DIV>
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[mwhities]

Not sure about the Sherwood but, the Apeks will not give you any troubles. I don't own one personally but, I've read plenty and talked to a lot of people in the DIR/Tech workd and Apeks are top notch.

Apeks DS4 and XT50/ATX50 will be my first doubles rig. The ScubaPro MK25 is rated really well in the Tech world as well. I only wish STs sold them.

Michael

[cummings66]

I bought the xtx50 based on word of mouth, the primary will be the DS4. Actually 2 of them assuming I can find an H valve for the older Genesis/Sherwood tanks I have.
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<DIV>I hate to break down and buy new tanks to support a valve I want/need for a tech class.</DIV>
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<DIV>However that's the basis of my question, I know of only one instructor who turns off the tank pressure and the others all say he's loony for doing it, yet I know in the tech world it's an accepted practice which doesn't hurt things.</DIV>
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<DIV>I'd like to know for sure if the Blizzard will survive it though. Maybe somebody will know for sure.</DIV>

[Dive-aholic]

It shouldn't be an issue. You'll be cutting pressure to the regs for only a short time. When you turn the valve back on, the first thing you'll do is blast some air through the reg to clear it. Valve drills must be practiced if they are to become 2nd nature in a real situation.

[chrispete]

Originally Posted by scubatexastony

ps... wass up! Chris?????

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<DIV>It's me, how are you guys liking the woods after living in paradise for all that time?</DIV>
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<DIV>Back on topic. I don't think that the air bleed system on the Sherwoods would give you any trouble because the pressure inside the reg is most likely still above ambient pressure, just not enough to make the bleed work.</DIV>

[woody]

Originally Posted by cummings66

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Here's the question I've been pondering.


I've been told by almost every dive shop I've been to that you never want a first stage to lose pressure under water by shutting off the valve because it will flood and need to be serviced. Not to mention the SPG may be damaged.

It is possible that you will get some water past the second stage and into the hose leading to thefirst stage. You should not get any water in to the first stage at all under the condition that you are doing a valve drill.

What's the truth of the matter? Are there some first stages that won't flood, brands? I am of course assuming that all the first stages we're using are sealed environmental types because in the <?:namespace prefix = st1 ns = "urn:schemas-microsoft-comffice:smarttags" /><st1lace w:st="on">Midwest</st1lace> the water is usually cold.

All environmental sealed first stages do not allowwater to enter the regulator at all. That is what gives them the environmental seal. Most non-environmental sealed regulators allow water to enter the regulator to increase the pressure that is delivered to the second stage. This keeps the regulator system performing the same at 10' as at 80'.
Thanks,
Woody

[woody]

Originally Posted by mwhities

The ScubaPro MK25 is rated really well in the Tech world as well. I only wish STs sold them.

Michael

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But they do have the Atomic's. Which rate the same or slightly better in most reviews that I have seen. I personally have been diving Atomics for ten years now and have beat the ...... out of mine. Still works like a charm. I know own about .... Well too many for sure. Almost everyone I put in Tech gear I put in to the Atomics. Some I will put in to the Zeagle's if they need a diaphragm regulator.

Thanks,
Woody