Why is the 3000 PSI Fill Standard at Most Dive Destinations?

[BHB ScubaTroll]

I don't know of many boats here pump to 3500 but most shops will.

Wow. Around here you get the "lecture" just for mentioning it...

 

[Teamcasa]

So, who in Cali is pumping tanks to 3500?

I don't know of many boats here pump to 3500 but most shops will.

Wow. Around here you get the "lecture" just for mentioning it...

Let me be clear (I did not read all the way back).

HP steel tanks get filled to that pressure. Many overfill by a few pounds to allow for pressure reduction after cooling.
AL tanks get the same treatment but limited to 3000 psi. No "cave fills" is SoCal, as far as I know.

 

[BHB ScubaTroll]

Let me be clear (I did not read all the way back).

HP steel tanks get filled to that pressure. Many overfill by a few pounds to allow for pressure reduction after cooling.
AL tanks get the same treatment but limited to 3000 psi. No "cave fills" is SoCal, as far as I know.

Sure, change your story now, Dave...

 

[Scubagolf]

So, who in Cali is pumping tanks to 3500?

Check out the bottom of this page for the Peace, which is one great dive boat: About Peace Dive Boat

Or, go to this web page for California Dive Boats and check out the air fill column.
http://www.californiadiveboats.com/

 

[BHB ScubaTroll]

Check out the bottom of this page for the Peace, which is one great dive boat: About Peace Dive Boat

Or, go to this web page for California Dive Boats and check out the air fill column.
California Dive Boats : The Official Page

OK, done. I took both to mean they have the capacity to fill steel tanks rated for 3500 psi, not that they fill every tank to 3500 psi.

It is something I've seen before that lets me know my Steel 100's will get their rated 3500 fill. It DOES NOT indicate to me that all tanks will receive a 3500 psi fill.

Is this what your original post is based on?

 

[Scubagolf]

I have learned quite a lot from the responses to my original post.
I never really thought much about fills on the trips I make, so long as I got AL 80's filled to about 3000 PSI. You are no doubt correct that the 3500+ fills advertised by local dive boats refer to steel tanks and not AL 80's. It is good information to know.

 

[dpaustex]

Many of the posts talk about pressure.

Tanks are rated by pressure and cubic feet. What you're interested in as a diver, is how many cubic feet of air it holds at sea level. A physically "smaller" tank can hold the same VOLUME as a physically larger tank, but of course the pressure would have to be higher on the smaller tank.

For those of you gas law afficiondoes, that is Boyle's Law, which states to gas volume is directly proportional to the inverse of pressure.

But the people that MAKE the cylinders make them at a certain pressure rating. Nothing sinister there. A higher pressure rating on a cylinder requires thicker walls on the pressure vessel.

DIN connectors also allow higher connection pressures, just due to the way they're constructed, versus yoke connectors.

 

[NAM001]

i would expect that the diving industry has settled on the al80 because it is most economical to produce, holds sufficient air for most recreational diving purposes, etc. There are other places on earth where the population hasn't come up to date yet and still use steel tanks and drive on the wrong side of the road, like britain, but that is rare. Al80's seem to suit the rest of the world just fine and will remain to do so probably forever.

the dive industry is going to side with what ever is popular. As long as poopular al tanks are cheaper to buy than the steel more expensive tanks, cost will overrule the tank purchace. Look around your dive shops and check out rentals to buy..... You can always buy year old al's cheap. Try to buy a year old steel. Hard to find they usually dont sell till first hydro. Many of these backwood countries buy once and use for years and years. However in america be buy, use once and throw away. Lets look at another thing about steel tanks, ignoring the opinions of the overfill police. My faber steel tanks are fillied overseas to 4k. Only diference is the valve whivcch is a stronger valve and weighs another 1-1.5 lbs. I wonder what they fill al's to overseas...... 3000 i bet is the answer. They are not strong enough to handle more than that. Get what you pay for. I can over fill with no problem and itf i stay within the paronoid 2400# stamped limit i have so much more safetyzone as far as presasure fractures goes. Next item is why would a boat use anything but throwaway tanks al's..... With all the water that gets into them from careless handleing and open weather.

Remember the comercials that shows toll booths and parking places and everything says bobs lane and bobs space . I am glad to be diving in bobs pond with bob quality gear. Btw show up somewhere with steel on your back and look at the crowd stare at the good stuff. When you get boared with that try a dry suit and get a new level of admiration from the "commoners"

what should you drive on ,,, a 30 dollar tire that lasts 30k or a hundred tire that lasts 90k. Seamms that the 30 dollar deal is tha way to go however the 30 dollar tire has low tread the last 10k of the tire like the 100 dollar version... Lets see 30 dollar for 20 k of good tread or 100 dollar for 80kof good tread. Funny how the 100 dollar tire is the best deal after all.

Take an al tank to some locations and they will refuse to fill it untill that shop doea a vis and eddy for 60-70 bucks. Domnnt have that problem with steel. They are even cheaper to use. I have been to shops that will not fill an al tank beyond 3000 hot. End up with 26-2700 cold. Dont have that problem with steel. I say 3000 hot and it cools to 2750 and god save us all i am 100# over the 2400+ of 2640. Not to mention that steel handles teh heat transitions beter than al. So its up to everyone to pick thier own poison, or side of the street as was mentioned. Btw i dont think that the right side driving is as popular as one thinks it is. It is the only side the us knows, like the non metric measures. Ill take the mis of both worlds. Steel tanks filled to lbs not bar.

As forrest gump said thats all i have to say about that.

 

[scubadobadoo]

My favorite tank is my PST HP 80! Man this thing is great for shore diving in Cape Ann and Cally where you sometimes have to be a mountain goat to get to the water. It holds almost the same as an Al 80 and weighs less and is smaller too. It's a shore divers dream!

Of course my steel tanks are useless in warm water for me.

The right tool for the job is best, steel or aluminum, as long as i get to dive.

 

[adm3745]

I havn't noticed a very large price difference between Al and Steel LP tanks. New Al 80's seem to run 160-200, where as LP 77 are 199. Would boats prefer 2700 full fills, much smaller tanks, and less lead?