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luis
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Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: SEA HUNT LIVE! 2011

Mon May 30, 2011 2:23 pm

antique diver wrote:RE: TANK FILLING PHOTO...

I'm sure glad to see that someone else still fills their tanks in water to keep the pressure loss to a minimum! We seem to be in the minority these days, but I sure like the extra 200 psi that I end up with in my steels. Don't believe everything the chrome & glass dive "boutiques" tell you about that.

With a slow hot fill (especially with hot air coming directly out of the compressor) a wet fill makes a big difference.

If the tank is filled and soaking in water for 5 minutes or less (like in many dive shops with banked air) it makes absolutely no difference. The air inside the tank will be hot, but the tank itself will not even have a chance to get hot for several minute. The tank will actually be warmer several minutes after the fill than it was when getting filled.

For a wet fill to be effective it is best for it to soak a minimum of 10 minutes, but preferably more. This applies to both aluminum and steel tanks, but it more noticeable on steel tanks.

The information above is based on analysis, calculations, and some casual testing that I have performed.

Wet fill do not introduce water into the tank… negligence when hooking up the tank is what gets water into the tank. The tank valve and fill whip have to be blown dry before connecting to the tank for every fill if you want 100% assurance that no contaminants or water will be pushed into the tank during the fill.

If a shop is doing quick fills (< 5 minutes), they are IMHO already a bit negligent and therefore adding water to the mixture is probably not a good thing. IMO they are already not being very careful. Therefore, I prefer they didn’t play with water while handling my tanks.

For a quick fill I prefer an 11% over the actual working pressure. For a steel 72 WP = 2475psi. Therefore a hot fill to 2747 psi is OK. When it cools down it will be around 2500 psi which constitutes a decent fill. The 2750 psi is not an overfill if the tank is hot since the pressure will drop when the tank cools down. This hot fill meets CFR49 as log as the tank temperature never exceeds 130F.


I didn’t want to hijack this thread, but it was a bit late.


Thank for the pictures. It sounds like you all had a good time.
Luis

Buceador con escafandra autónoma clásica.

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