How do you tell if the bottle is empty

[Andy from Workshopshed]

I was using Argon from a regular bottle and it appeared to cut out and the welds went all "rust". So I assumed that I was out of gas.

Checking the regulator the flow rate and pressure were also zero.

However when I took off the regulator and simply opened the valve there is definately a sound of gas coming out although it does not sound like it's high pressure. Is it this normal?

Is the gas definately empty and hence ready for a refill?

 

[Luke]

Its pretty normal for the bottle to still hiss, it will still have gas in it.

If the regulator says its empty, and the welds look like there's no gas, then its quite likely there is no gas.

The regulator will always have a pressure drop across it, due to the way it works.

 

[madkayaker]

a hiss can be air flowing back into the bottle if the temperate is different (therefore the pressure) or it can be gas escaping but not enough to allow any flow through the regulator

 

[backpurge]

If the gauges are both at zero and there is no gas coming out of the torch there is a good chance the cylinder is empty,dont understand what you mean by "the welds went all rust" but you say you are using argon so I am presuming you are TIG welding, when the gas runs out the electrode will become badly contaminated.

Even though all the gauges are at zero you will still have a bit of residual pressure in the cylinder though not enough to weld with

 

[Andy from Workshopshed]

Yes, TIG welding on steel. When the gas runs out you very quickly get yellow/rusty dusy all over the weld.

Thanks for the quick responses, the pressure is so low I can stop it with my finger. It's no good for welding and hence needs replacing.

 

[Luke]

the pressure is so low I can stop it with my finger.

Crikey, don't try that with a new bottle at 200 bar!!

 

[backpurge]

Crikey, don't try that with a new bottle at 200 bar!!

Seem to remember hearing somewhere that gas only needs to be at 10 bar to permeate the skin

 

[Andy from Workshopshed]

Crikey, don't try that with a new bottle at 200 bar!!

Ok, will add that advice to things not to do list.

 

[piman]

Hello Backpurge,

"Seem to remember hearing somewhere that gas only needs to be at 10 bar to permeate the skin "

Which is why it can be dangerous to blow yourself down with an airline.

Alec

 

[Robotstar5]

Which is why it can be dangerous to blow yourself down with an airline.

I'm sure I've read somewhere blowguns are supposed to be limited to 2 bar for that reason

 

[piman]

Hello Robotstar,

I hadn't heard that about blowguns, but as it is so easy to plug any gun or even a home made lance into an unregulated air line, the 2 bar limit is easily overcome.

Alec

 

[overload]

Well it's not gonna stop me using my blowgun for a blow down no matter what the H & S bods say!

 

[biosbill]

What...2bar?! That'd be useless!!

William