Prebreathing regs

[TSandM]

The biggest problem is the adiabatic cooling of the expanding air coming out of the first stage. First stage freezing is the big issue. The moisture from your breath has no effect on that. The pressure drop from the tank to the outflow of the first stage is the big drop, and the big energy change.

 

[Rick Inman]

(and why would anybody inflate their dry suit BEFORE descending?)

To purge out the air and replace it with argon, of course. Sheesh, you WWWs in the Puget Sound...eyebrow

BTW, I'd be more careful in fresh water than salty.

 

[Kwbyron]

Is there a good source somewhere that really explains and breaks down how regulators work? maybe with cutaway photos and such? I know the basics; high -> not so high -> ambient

 

[Snowbear]

The Airspeed Press Regulator book is awesome!

 

[Kwbyron]

cool, I'll see if I can find it. thanks.

 

[Snowbear]

Click the link indicated by the blue underlined text in my previous post...

Then click the Online Ordering Info in the menu on the left of the page to order it

Well worth the $$ spent, IMHO. As are the Exposure suit and Gas mixing books, though I didn't find the dive light book that useful for my needs...

 

[cerich]

www.scubatools.com the REGULATOR SAVVY BOOK

 

[TSandM]

I would agree that the dive light book is the least useful -- it's mostly aimed at people who want to build their own lights.

The other two were excellent, but I'm also going to buy the one cerich recommends.

 

[JohnL]

What you need is a set of Poseidon regs on independant doubles!!!

A friend I dive with uses an unsealed piston reg(oceanic not SP) down to 36 deg. He swears by using the proper technique and hasn't had a problem in five years. Pretty much orally inflates the wing, doesn't pre-breath on the surface annd does a fast drop down before breathing the reg.

I was a bit concerned at first, but we have even done several air shares in 39 deg water with no freeflow.

I know unsealed regs aren't recomended in those temps and I'm not saying anyone should do it....but it does appear to technique dependant.

 

[Thalassamania]

Frankly, if it's a worry I'd seal the regs. But frankly I've had remarkable luck with the Oceanic 1st stage under very adverse conditions.