[TheJDMan]

Can anyone tell me what the difference is between a D.O.T. vs ISO/US marked cylinder and why? My LWS told me that they will not refill a cylinder if it is not D.O.T. stamped.

[Poland308]

Technicality. There probably covering there legal butt. If they take it in and have to ship it out to retest the tank then they take the risk of getting dinged by the dot. It's an excuse some places use to keep from having to take in tanks that aren't there's.

[Otto Nobedder]

If it's not got an approved DOT stamp, it's illegal to transport it once it's refilled. It's a "one-time use" or a "fill on site" cylinder without the DOT stamp.

The DOT has specific retest requirements and standards that must be met to transport them on public roadways.

Same for the vessels I work on. Every five years, I retest them for DOT certification (Also valid in Canada.)

Steve

[zeighty]

This is an old post but if you found it you may be looking for info on cylinders that do not have DOT stamps on them.
Here is he skinny on ISO markings... do an internet search for more info.

"DOT-stamped cylinders are acceptable for transport to, from, and within the United States. UN/ISO-stamped cylinders must have "USA" country of approval marking to be acceptable for transport to, from or within the United States."
UN/ISO stamped cylinders have better specs that DOT cylinders.

[Jack Ryan]

UN/ISO-stamped cylinders must have "USA" country of approval marking to be acceptable for transport to, from or within the United States."

What does that look like? Our cylinders are UN/ISO but there is no country stamp except for the manufacturer.

Thanks