CGA 580 valve/CGA 540 valve

[DonnyT]

How can you tell the difference between these two valves?? I'm looking to purchase a c25 80cf welding tank with a CGA 580 valve. I would like to tell the difference from a 580 or a 540 valve so I do not purchase the wrong tank. Thx.

 

[JonnFX]

It looks like the 580 is a bit larger.

Here, this might help.

Also, you can take the 580 fitting and see if it threads into the tank.

 

[DonnyT]

Thanks John, good idea.