Filling LP tanks to high pressure

[captain]

So if the hydro strain is permanent...we gain some tank capacity with each hydro? Some of tanks I've seen should be quite a bit bigger than they started out.

If you are capable of seeing an increase in capacity measured in cubic centimeters you should never have need for a tape measure. Those would be some incredibly calibrated eyeballs.

 

[ianr33]

I just inherited 2 LP Faber 130s that has the 2400+ symbol on them

Are you sure it's not 2400T?

Turn at 2400. Fill to 3600. It's to help math challenged Cave Divers.

 

[Scared Silly]

They are both 3AA tanks. That is the exact same spec stamped on both tanks.
There is a lot of miss-information spread about thanks, but this one there is just no room for debate... the spec is stamped right on the tanks. And you can look up CFR49 and get all the details that applies to all 3AA tanks.

Luis, your point is well taken and we are going to be pick nits here. I said design spec rather than minimum spec. The 3AA spec is a minimum spec. As such, let me rephrase my statement. While LP 72 tend to meet the minimum 3AA spec whereas modern LP cylinders go beyond the minimum. As such, I would not over fill LP72.

As analogy would be emission controls on cars. There is a maximum amount allowed. Some emit that maximum some less. But both meet the same EPA specs.

 

[Traijin]

When things go wrong.

View attachment 174841

A scuba tank left in a car on a hot day.

That's a long way from what happens when a burst disc pops. There's a lot more that had to happen for a catastrophic failure of that type. A burst disc is about as loud as a shotgun followed by prolonged air escape hissing. Throw a towel over it until its empty, get a new burst disc and re-hydro. The previous is the reality as compared with the anecdotal picture of an exploded truck. That more like what happens to a cylinder in a fire.

 

[flots am]

I'm sorry if this has been covered before, but I am looking for a definitive answer. I just inherited 2 LP Faber 130s that has the 2400+ symbol on them and the guy told me you could pump these tanks up to 4000psi in "cave" country. Then I ran across a thread that said LP tanks are made with a different material than HP tanks. So are we wrong about pumping the tanks up past their rated pressure that we have heard and done for many years?

You probably won't die. OTOH. you might. My life is worth more than that. Also, the overfills shorten the tank life making them fail hydro sooner.

I own a whole bunch of fabers and never overfill them.

If the tank could safely and reliably hold 4000PSI over a long service life, the manufacturer would have rated them for it.

 

[Jim Lapenta]

My LP 95's, 85's, and 75.5's normally get filled to between 2800-3200. Depends on how much gas I use and where they get filled. My LP 72's usually around 2700 -2800. Those are the newer ones from the 1970's. The older ones from 1953 and 1954 are pretty much used only on the bench for reg service now and at most I fill those to around 2200. Just don't need more than that in them.

One thing I like about HP tanks even though I don't own any is one very busy place filled my LP85's to 3400 as they were in a line with others who were using HP tanks. I just smiled and said nothing.

 

[Jared0425]

I put 3442 valves on both. The only reason why I got these two water heaters was to replace my doubles on charters that did not allow or have the room to accommodate them. I do ot plan on taking them up to 4000, put 3400-3600 is what I would like to do

 

[AfterDark]

That's a long way from what happens when a burst disc pops. There's a lot more that had to happen for a catastrophic failure of that type. A burst disc is about as loud as a shotgun followed by prolonged air escape hissing. Throw a towel over it until its empty, get a new burst disc and re-hydro. The previous is the reality as compared with the anecdotal picture of an exploded truck. That more like what happens to a cylinder in a fire.

That wasn't a burst disk it was an entire tank. The explosion was caused by a scuba tank that ruptured.
I've been standing next to a tank when the burst disk popped, it's startling but not destructive. A piece did embed itself in the wall, glad I wasn't in front of it!


This isn't the same tank that wrecked the truck but it probably looked something like this after the explosion.

 

[Superlyte27]

When things go wrong.

View attachment 174841

A scuba tank left in a car on a hot day.

This wasn't a result of overfilling. Probably bad tank for whatever reason, if this is even the result of a scuba tank rupturing. We have no real data.
And it wasn't a steel tank.

---------- Post added January 5th, 2014 at 03:35 PM ----------

If you are capable of seeing an increase in capacity measured in cubic centimeters you should never have need for a tape measure. Those would be some incredibly calibrated eyeballs.

When Hydroing a cylinder, the cylinder and vat are filled with water. The cylinder is pressurized, and the increase registers via water growing through a graduated cylinder. We start at 0, stop at 5/3's pressure, and see what the stretch to the tank is via the water level in the graduated cylinder (as measured in CC's). Then we bleed the pressure. The tank must come back to it's original size (with a margin of +/- 10%).

---------- Post added January 5th, 2014 at 03:37 PM ----------

That wasn't a burst disk it was an entire tank. The explosion was caused by a scuba tank that ruptured.
I've been standing next to a tank when the burst disk popped, it's startling but not destructive. A piece did embed itself in the wall, glad I wasn't in front of it!


This isn't the same tank that wrecked the truck but it probably looked something like this after the explosion.
View attachment 174872

Notice it's an aluminum tank, not a steel tank. And probably bad alloy.

 

[kelemvor]

Wow, you guys get some big fills! I have been pretty happy with my LDS that routinely puts 3200ish in my LP108's.

There sure are loads of photos of tanks that have had catastrophic failures on the net. Is it (somewhat) common practice to deliberately blow them up after they've been condemned or something?