What broke

[OldNSalty]

I got a couple of tanks filled this weekend and on the way home I hear the loud sound of HP air coming from my trunk (which freaked out my passengers) I pulled into my drive thinking that maybe the valve got turned on but the air was coming from around the neck. Is this a burst disk or just the o-ring?
Either way, the entire tank emptied in about a minute, maybe a little longer. The experience made me realize the importance of having a good buddy or a pony. The tank is an old 72 that had about 3200psi in it, and we had stopped for lunch before heading home so it might have gotten a little hot.

 

[captain]

At 3200 in a hot trunk it is most likely the burst disc. You seriously need to rethink the 3200 psi fill.

 

[Bob DBF]

It was probabaly the durst disk. Since the old (steel) 72's are rated for 2250# the burst disk should go off between say 2800# to 3700# unless it was replaced with a higher rated disk. The burst disk is not a precise device it just relieves pressure before the tank integrety is compromised.

Sounds like the fill monkey thought it was a HP100, too bad it didn't teach him a lesson in the shop. I have a number of different tanks and always mention the 72 pressure if the guy filling is not checking the tank stamps. Now that the J-valve is back on there shouldn't be an error.

Bob

 

[OldNSalty]

So are all these disc created equal? Assuming I like the extra air with these tanks what could I do to prevent this in the future?

 

[OldNSalty]

It was probabaly the durst disk. Since the old (steel) 72's are rated for 2250# the burst disk should go off between say 2800# to 3700# unless it was replaced with a higher rated disk. The burst disk is not a precise device it just relieves pressure before the tank integrety is compromised.

Sounds like the fill monkey thought it was a HP100, too bad it didn't teach him a lesson in the shop. I have a number of different tanks and always mention the 72 pressure if the guy filling is not checking the tank stamps. Now that the J-valve is back on there shouldn't be an error.

Bob

The fill monkey didn't even know it was a steel tank-couldn't find the vis sticker or anything. He told me he wasn't allowed to fill tanks made before 88'. I said, 'that policy is usually for Al tanks-this one is steel.' That confused him for a minute. I then pointed out the vis and hydro and he took it back. Came back and said that he put about 3200 in each. I paid and left

 

[JohnB47]

If it is an "old 72," the pressure rating was probably 2250+, which means that you could fill it to 2475 psi IF the most recent hydro certified the "+" rating. Otherwise, it should not have been filled over 2250 psi. I am not sure what the burst disc rating would be on that tank, but probably not more than 3500 psi. If the tank were filled to 3200 at 80 deg. F, and then subjected to a temperature of 140 deg. F in the trunk of the car, the pressure in the tank would then be 3555 psi, which would be enough to blow the burst disc if it is rated at 3500 psi. If you want to run that much pressure, you really should get a high pressure tank.

 

[Rick Murchison]

... Now that the J-valve is back on there shouldn't be an error.

Bob

"Don't never assume nothin'!" Today's shop rats are liable to think they're looking at the "new, improved, super high pressure tank valve."
Not only is a J-valve no assurance against a serious overfill, unless you have the lever tied off or disabled you're liable to get a very high pressure no-fill
Rick

 

[OldNSalty]

The burst disc would need to be able to survive a hydro-so it should be rated to at least 3750 -right? Of course, the disc and o-ring could be original so maybe they were just old.

 

[Fishpie]

Hydro's are done sans valve.
Burst disks come in different pressures for use on different pressure rated tanks.

 

[OldNSalty]

Hydro's are done sans valve.
Burst disks come in different pressures for use on different pressure rated tanks.

Oh-yea. That sounds right.