Tanks-steel vs. stainless?

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Pez7378
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Post by Pez7378 » Fri Sep 14, 2007 1:44 pm

scottsax wrote::pale:

I was told there would be no math....


Me too! Just wait until you start doing Calculations for gas management. Then there is Nitrox and figuring Partial Pressures. #-o This is Gods cruel way of punishing me for cheating in school. I though I got away with something. Kids, this lesson is for you. Listen up!!

dsteding
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Post by dsteding » Fri Sep 14, 2007 1:51 pm

scottsax wrote::pale:

I understand that cubic feet is the VOLUME of air the tank holds. Psi is the delivery pressure of that volume of air? The density of that volume of air? The fill pressure (and if so, what does that mean?) All things being equal, is bottom time a combination of cf & psi?

](*,)

I was told there would be no math....


Choose your tank based on (a) your gas needs and (b) how it trims you out. As for the HP/LP distinction, this has been discussed here many times, but here it is in a nutshell:

A LP95 is the same size as a HP119.

A LP108 is the same size as a HP130.

LP85=HP100.

So, you can buy an HP tank and even if you can't get a full fill, you'll have the same amount of gas as its LP cousin. HPs are a bit more expensive, LPs are a bit more readily available used.

You can use your yoke reg with an HP tank if it has a "convertible" DIN valve with a yoke insert (300 bar DIN valves are too wide to be convertible).

For general shore diving around here (<100 feet) a LP95, HP119, HP100 or HP130 will work well.

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CaptnJack
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Post by CaptnJack » Fri Sep 14, 2007 1:55 pm

What you have to breath is only a function of CF.

If you had a dumpster sized tank it could be filled to 150psi and still give you an hour dive. A pea sized tank could be filled to 10,000 psi and give you the same volume of gas for an hour dive as well.

HP tanks will be a little smaller than an LP tank for the same volume. The former are often a little more negative when empty. LP are typically neutral when empty while HP are often -2lbs.

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scottsax
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Post by scottsax » Fri Sep 14, 2007 2:10 pm

=D> =D> =D> =D> =D> =D> =D> =D> =D> =D>

My OW & AOW instructor never explained it to me that well. My DM friend hasn't been able to explain it to me that well. :axe:

You guys RAWK!!! :supz:

:salute:

If (sorry, WHEN) I see any of you out and about, drinks are on me! :partyman:

Scott
I'm going to look like a moose on rollerskates. -airsix
... my Mom caught me fenestrating once. -lavachickie
And I get so tired of fainting and peeing all over myself when the hammer falls on an empty chamber! -Nailer

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diver-dad
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Post by diver-dad » Fri Sep 14, 2007 3:13 pm

Great discussion!

That's what I like about this place! :salute:
- DD

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Sounder
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Post by Sounder » Fri Sep 14, 2007 3:53 pm

scottsax wrote:=D> =D> =D> =D> =D> =D> =D> =D> =D> =D>

My OW & AOW instructor never explained it to me that well. My DM friend hasn't been able to explain it to me that well. :axe:

You guys RAWK!!! :supz:

:salute:

If (sorry, WHEN) I see any of you out and about, drinks are on me! :partyman:

Scott


Drinks on you?! I need to get in on this discussion...

For me the right decision was high pressure 130s. I can use them with a lower pressure fill and LOVE it when they're full and topped off cold. HP100s are a fantastic tank, though some guys here have them and are making the move to 130s or 119s. If you're a stout lad and can carry a heavier tank around like that, at least check them out before you buy. Let's go diving! I've got, ahem, one or two 130s around here somewhere. \:D/ I also have a couple HP100s too if you'd like to try them. Cost not being an issue, find the right tank by trying them out.

Also, if you can get to one of Grateful Diver's or BDub's gas management seminars before you buy tanks, you'll learn what kind of tank you need for the kind of diving you're doing (or want to do). You will be surprised what you learn... and the math isn't too painful - after all, even dsteding can do it! :bootyshake:

Let's go diving!!!

PS: Everyone here is very helpful and is willing to help newer folks get dialed in correctly the first time. Find a great mentor or mentors and learn from them. The board will help with this too. Then, pay it forward. Once you're experienced, help to answer the same questions you asked and take newbs under your wing to show them that there's more to this sport than silt and flailing arms. My OW instructor taught me how not to die diving, my mentors made (and continue to make me) me a good diver. :prayer:
GUE Seattle - The official GUE Affiliate in the Northwest!

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scottsax
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Post by scottsax » Fri Sep 14, 2007 4:07 pm

Sounder wrote:Find a great mentor or mentors and learn from them. The board will help with this too. Then, pay it forward. Once you're experienced, help to answer the same questions you asked and take newbs under your wing to show them that there's more to this sport than silt and flailing arms. My OW instructor taught me how not to die diving, my mentors made (and continue to make me) me a good diver. :prayer:


Oh, I'm all about mentoring. As a musician, I've had some amazing ones, and I pass on knowledge to younger musicians every chance I get, in formal instruction or casual, on-the-bandstand lessons. So far in scuba I've only been able to share enthusiasm. Soon, hopefully, there'll be experience to pass on as well.

A couple of things need to happen for me to dive as much as I want to-I have to make it through the formality of the interview process at work to get the $$ I need, and I need to resolve my transportational handicap (broken truck). Hopefully the truck will be running this weekend, and in a week or 2 cost really WON'T be an issue. Having said that, I'm shooting for diving 3 Tree North next weekend with some friends, which means I can stop fantasizing about diving and actually go DO IT!

:prayer:
I'm going to look like a moose on rollerskates. -airsix
... my Mom caught me fenestrating once. -lavachickie
And I get so tired of fainting and peeing all over myself when the hammer falls on an empty chamber! -Nailer

Want to know where I'm performing? Check out my Facebook fan page!

dsteding
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Post by dsteding » Fri Sep 14, 2007 6:18 pm

Sounder wrote: You will be surprised what you learn... and the math isn't too painful - after all, even dsteding can do it! :bootyshake:



Oh no you didn't. [-X

I challenge you to a math-off. Trust me, you will die. Scuba math is my specialty-even Lynne (who has a degree in mathematics) is awed by my scuba math skills.

It is on. Bring it.

:angryfire:

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Sounder
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Post by Sounder » Fri Sep 14, 2007 7:17 pm

dsteding wrote:
Sounder wrote: You will be surprised what you learn... and the math isn't too painful - after all, even dsteding can do it! :bootyshake:



Oh no you didn't. [-X

I challenge you to a math-off. Trust me, you will die. Scuba math is my specialty-even Lynne (who has a degree in mathematics) is awed by my scuba math skills.

It is on. Bring it.

:angryfire:


...and you're humble about it too!!! :bootyshake:

I accept your challenge for a math-off... but why limit it to such easy things like scuba math?! ANYONE can do that!! How about Calc, Geo, and Trig? Then again, perhaps it would be better to stick with multiplication, subtraction, division and addition (that's where you take two numbers and count "how many" they are together). :bootyshake: :bootyshake: :bootyshake:
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rcontrera
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Post by rcontrera » Sun Sep 16, 2007 1:02 pm

Just a quick note on the original subject (sorry for bring this back up, but ...), stainless steel tanks were made up until the early 80s. If they have a stainless tank, it was never built for diving. They were used in the medical field.

Unfortunately, when the word got out that a little company was going to introduce a scuba tank that didn't require visuals and a hydro only every ten years, the labor unions decided to press for unionizing the plant and they ended up going out of business.

Currently, stainless steel cylinders are only available in 1800 PSI service (as far as I know) and are pretty small.

decodiver25
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Post by decodiver25 » Sun Sep 16, 2007 1:49 pm

yup im always learning and i love it....
When you think you know everything is actually when you know nothing...

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