LP 80 Tank Question

[Nemrod]

The "girl" at the lds (who is a PadI Instructor) only knows one setting on the compressor. I have tried to explain to her but it goes in one blonde ear and out the other. All tanks are filled to 3300 psi when she fills them. I just bleed them down. The LP 80 (84?) you have can easily handle those pressures. I like the 3,000 in it. But I am a Rebel. I figure sooner or later she will blow something up. Oh well.

I always tell the fill guy to pump them up until they swell and bulge a little, that is how I know they are full. They always get these big eye looks. No worries, nobody is leaving the planet alive.

Take a Sharpie Pen and write on the top of the cylinder the rated fill pressure in big letters. This helps the guys put the correct pressure in them. N

 

[cave_diver]

First, the filling pressure has nothing to do with current Hydro. If a tank is rated for 2.640 psi, it shows 2.400 and a plus-sign (+). However, these tanks have a big safety margin. Perhaps your dive shop is usually filling Aluminum cylinders, which are mostly rated 3.000 psi. This is why you get 2.800 psi. They may have set their compressor to automatically shut off at 2.800 psi, and they don’t spent attention. Furthermore, if your tanks are sitting in the sun, air will expand. Perhaps this was the reason why you did read the 3.400 psi.

 

[Gombessa]

Interesting. Same thing happened to one of our tanks (LP80 came back with 3600), this was right after it was hydro'd too, so we figured it was a monster fill bonus to take advantage of the new plus rating. Turns out the shop probably just made a mistake That's a mistake I'd be happy to have repeated, frankly. We typically get our LP fills to 3200-3300. Just don't leave the tanks in a hot car.

 

[DA Aquamaster]

The "girl" at the lds (who is a PadI Instructor) only knows one setting on the compressor. I have tried to explain to her but it goes in one blonde ear and out the other. All tanks are filled to 3300 psi when she fills them. I just bleed them down. The LP 80 (84?) you have can easily handle those pressures. I like the 3,000 in it. But I am a Rebel. I figure sooner or later she will blow something up. Oh well.

I used to own a wonderful set of double steel 45's that had an 1800 psi service pressure. It was common to come back and find them filled to 3000 psi just like a set of aluminum 50's despite the "1800" highlighted in red. They look about the same they must be the same. Right?

I had to explain to more than one fill operator that 3000 psi was actually the test pressure on those particular tanks. I also explained that once when they tried to charge me for the burst disc that let loose during the fill.

 

[Gombessa]

I used to own a wonderful set of double steel 45's that had an 1800 psi service pressure. It was common to come back and find them filled to 3000 psi just like a set of aluminum 50's despite the "1800" highlighted in red. They look about the same they must be the same. Right?

I had to explain to more than one fill operator that 3000 psi was actually the test pressure on those particular tanks. I also explained that once when they tried to charge me for the burst disc that let loose during the fill.

I've just gotten into the habit of placing a strip of painter's tape on the crown which says "AIR TO XXXX PSI PLEASE." It's impossible to miss, and if they don't trust it and look at the fill pressure stamped on the tank, then at least they're doing their job.

 

[Nemrod]

I've just gotten into the habit of placing a strip of painter's tape on the crown which says "AIR TO XXXX PSI PLEASE." It's impossible to miss, and if they don't trust it and look at the fill pressure stamped on the tank, then at least they're doing their job.

In a perfect world, you would think but I assure you that the "girl" would fill them to 3,300 psi. N

 

[oxyhacker]

Years ago, when "Genesis" was synonymous with "HP" , I grabbed some free big round Genesis tank stickers at a dive show. Just for fun I stuck them on a set of old yoke-valved, doubled steel 72s - I repeatedly had to stop diveshops from tryingto put 3500 psi into them! The tanks were clearly not HPs - 72s are muc skinnier, and they were clearly stamped as such. But often as not, when I told them to stop, they would argue with me insisting they were HP tanks!

Actually, if worked pretty well. If I timed my intervention just right, I'd usually walk out with 2700-2800 psi.

 

[SparticleBrane]

...be aware that in a fire the tank is likely to explode before any gas is vented by a properly rated and functioning burst disc.

Are you sure about this? What is the melting point of the o-rings generally used in the cylinder neck? Personally I would imagine they'd melt before the cylinder would explode, but I'm not an engineer.

With the availability of high pressure tanks rated to 3442 psi that are essentially the same size weight and buoyancy as LP tanks that hold a similar volume at a similar 3500 psi pressure, there is not as much argument for buying and cave filling a low pressure tank.

Sure there is!
Back in February I received an email from my LDS about their Valentine's Day sale, and about halfway through it I saw "All PST cylinders 50% off!!" I ran to the dive shop, where they only had 4 PST cylinders (trying to get rid of old stock). They had an MP72, an HP80 (3500psi), and 2 LP80s.

I grabbed the LP80s which were "brand new" with an original hydro date of 2002 but they'd been sitting on the sales floor their whole life. They'd never been used and were stored with ~100psi in them. After a $4 VIP and $10 hydro each, I was in business. Lucky me, the hydro place even tested for the plus and used the PST procedures, both on my request -- can't beat that! Especially since they were $150/cylinder... Definitely an impulse buy but sometimes you just can't pass up a good deal.


...of course, maybe this is just a special case.