cylinder question

[vipermanz]

i was wondering today, at what pressure does the argon in my tank become obsolete??? i.e i started out with 2000 psi and now it's around 700, do i wait to 0psi to swap it or do i swap it at like 35psi??:)

[malibu101]

Use it until it's gone, it's all the same no matter what pressure.
With actylene tanks, I was told to never use them with under 15 pounds of tank pressure. If used at low tank pressure you could suck acetone through. That's what I do.

[donbappy]

WoW ! VERY DANGEROUS!!!!!!!!!!!!!!!! Never operate a actylene regulator over the 15# psi. Do not operate in the red zone of the regulator. U will suck the acetone into the regulator and valve and may not be able to it shut down . I was tought to leave at least 25 lbs in the cylinder. It helps pervent moister /condensation inside the cylinder .U need to read a safety manuel on Oxy/Actylene operations.

[fla jim]

donhappy;
I think you misread Malibu's post. He was talking about tank pressure, not regulator pressure.
It's good to post when you see something you think is dangerous.
But with acetylene the problem with excessive line pressure above 15PSI actually is "explosive disassociation", where acetylene disassociates into hydrogen and CO2
What your talking about is high feed rates, where Acetone is drawn into the regulator. Acetylene is desolved in acetone in "porious media" in the acetylene cylinder to keep it stable. The rule is you should never draw more than 1/7th of the cylinder volume per hour.

[Franz]

Just one addition to Jim's post, a regulator itself is a lot like a check valve, so when the regulator is installed, AND properly functioning, it is NOT possible for gas to enter the tank thru the regulator.
It's almost impossible to completely empty a tank, once the tank pressure drops below usable pressure, your process will obviously malfunction at the working end of the system.
Acet tank pressure will drop to about 5psi, and you'll be unable to sustain a flame cause the tank can't deliver. If that tank is then warmed, the pressure will go up, but yield very little quantity of usable gas.
The same holds true with Propane
Gases such as Oxygen and Argon, or mixes, exhibit different propertys from fuel gases, when they are gone they are gone, and warming the cylinder won't yield any additional gas.
All pressure vessels should be left with the valve closed when empty, or they can accmuulate contamination in the cylinder.

[vipermanz]

any idea on what usable minimum pressure on argon is franz???

thanks!!

[cutter]

Originally posted by fla jim
The rule is you should never draw more than 1/7th of the cylinder volume per hour.

I actually woke up earlier wondering about this 1/7th thing. If I have say, an 80 cu ft cylinder & its
already half empty, does the rule mean I should not draw down more than 1/7th of the original
80 cu ft volume or should I not draw down more than 1/7th of the remaining (roughly) 40 cu ft in an hour?

[fla jim]

The original 80 C'. I believe the limiting factor is the ammount of acetone and volume of porious media being able to release disolved acetylene.

[cutter]

T'anks. ;)

That's what I thought, otherwise it would get into a ridiculous thing kinda like a diminishing duty cycle.


cutter

[Franz]

Originally posted by vipermanz
any idea on what usable minimum pressure on argon is franz???

thanks!!

Probably around 5# when it's a half inch from the ned of the weld and you don't have a spare cylinder. Believe me, you'll know when it runs down to the point you aren't maintaining a shield around the tungsten.:D

[didlysquatts]

why would ya waste gas?

[vipermanz]

not waste, just wanted to know what was what.. i'm still new at this, that's what franz is for!!!