over fill a low pressure steel tank?
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Burst disc's are supposed to be able to hold 90% of testing pressure. an al80 is 4500 psi. As test pressure is based on working pressure and not the + rating then a lp tank is 90% of 4k or 3600. the burst disk is to bow between 3600 and 4k,. or for some of you between 90-100 % of test pressure. As fill pressures go the us calls working pressure as 1/4 of tank burst pressure. Its called a safety factor. the US uses 4 and other counties use less so a country that has a factor of 3 will fill higher than the us for the same tank. this gets complicated in that if other countries make tanks with different alloys then you can compare apples with apples. AS we all know this material factor is involved with the dot stamp that insures tank material and proper rating for the US.
Jacob Plunkett
Registered
I just recently purchased 2 AL80's and 2 LP95's
the AL80"s have 5250's on them and the LP95's have 4000's on them, should i swap the LP's to 5000psi disks, i plan on filling them to 3800 and let them settle cooled around 3600 as my first stage is a yoke rated to 3600psi.
will the 4000psi burst disks weaken overtime filling to 3800?
also off topic, will i be ok filling an AL80 to 3500 cold?
Absolutely NO to swapping those burst discs, because you compromise the safety feature on your 2400psi LP95's. They are hydroed to a 4000psi test pressure; if say your tanks were heated and the pressure exceeded 4000psi, the 5000psi burst disks wouldn't go. Now you risk the tank shattering because it's way above it's working pressure & hydro test pressure. It's placed beyond it's testing pressure requirements, so ie. fancy bomb you got there now.
The burst disc's purpose is to prevent that, which is why it came with 4000psi burst disc.
Also I don't recommend hot fill or cave fill; yes I'm being an evangelical PSI Inspector. If you want the added volume, buy a bigger tank, learn to dive with a stage, or learn doubles.
What I recommend is fill it at a rate of 100psi/10seconds and top off the 300psi lost after it cools down.
4-5 minutes to fill those tanks. That's nothing for personal filling. 20 minutes out of your day if you're filling one at a time.
Can you get away with filling a Al 80 to 3500 and leaving it? Sure if it's integrity is stable. The most dangerous time for a tank to fail or a valve to fail is when you're filling or increasing the internal pressure (say from heat).
As for your reg yoke rated to 3600psi, I personally like staying well below pressure ratings. If it says 3600psi I'll blindly assume it shatters above that; why? Because the first stage usually sits near my manhood when I'm turning the tank on and I like my manhood the way it is. Even though yes, the Mfg's usually put a conservative rating on it, but I don't know what that actual avg number is.
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I don't know how much effect your comments will have because they come directly form a book. Books are written by lawyers for legal protections so no one respects the book contents when it comes to having valid information as opposed to letigous information. You can equally turn your point of view around for the opposite opinion. lp tanks have a min burst psi of over 10,000 psi the us has a 4:1 safety factor making the working psi 1/4 of min rupture psi. that how the 2400 came about. Its hard to scare people with armagedon 4000 psi when the tank is tested at that psi and has a much larger rupture psi. The 2400 psi is designed to guarantee 10000 fill cycles to working pressure and still pass a recertification process. Is it wise to tempt fate? NO should peole do it? NO are they signing up for the death sentence for over filling? NO. Exceeding working pressure decreases the total (10000) fills you can expect before failing the hydro. Ihave spoke to my hydro guys and they say my tanks recover fully. not 97% but fully.
We come form a country that puts tags on Halloween constumes that say "wearing this comsstume does nto allow the wearer( who probably can ont read) to fly". You can easily predict societies reaction to your quoted book statements as a serious life protecting warning.
I'm not saying your are loony tunes. what I am saying that to the public one incident in perhaps a million fills is not a serious concern. Its human nature that has to be changed if you want people to obey rules and regs. I guess yo can call this a form of civil disobedience to many.
Do I over fill , YES I do....... hardly ever do I take an lp tank out with less than 3k in it. normally 3100 is the fill I give them. DoI fill for others NO only my self.
I think that most will look at the no overfilling of tanks the same as the warning of "You can die if you fly"
PSI is a tremendous organization...... However as you are a PSI inspector you have to remember that the purpose of PSI is to promote proceedures that if followed "PREVENTS YOU FROM BEING FOUND GUILTY IN THE EVENT OF A LAWSUIT. If you are pappered correctly and can prove you followed the preceedures you are damage free in a litigation. They tell you that UP FRONT in the course. Most lkely if you do comply you wll never get sues to begin with. The primary emphasis is still litigation protection.
DogDiver
Contributor
Yep you sure can, and I do, at this very station. The identity of this station is unimportant. What is important is that those that use it know what they are doing and many are certified fillers themselves. Just a guess.....99% of the users probably know more about filling than 99% of the shop fillers.(globally)
Bob DBF
Contributor
I use the proper burst disks for my tanks, I mostly get the rated pressure fills. Sometimes I get overfills that are close to burst disc pressure, however I replace the disks when I rebuild the valve at hydro and have not had an issue so far. I probably would not do cave fills if I could get them, but I understand the reasoning and don't have an issue with it if the diver and filler agree it works for them.
Bob
Bob
Michael Guerrero
Contributor
I use plugs.
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