Regulations concerning tank fills

[in_cavediver]

LOL!! Yep

What people need to realize is that its very unsafe to fill a tank at a lower temp then it will be stored in.

Its important to know that for every degree in temp a tank changes, the pressure changes by 5psi. so, if you fill a tank during the summer in a "cool" liquid, then send it out the door to a customer at a full fill. Then he puts it in his trunk or in the direct sunlight while transporting it, there is a very REAL possibility that the burst disk could rupture.

Have a guy come back into the shop accusing you of not filling his tank and you will become familiar with these types of physics.

OK, Given your statement that for each 1 degree in temp, 5psi change. Lets assume the worst.

Fill to 3000psi. Increase ambient temp by 100 degree's. Thats only 500psi more for a total of 3500psi. I have personally seen an al 80 filled to 3800psi. It didn't blow the disc. (and we chewed out the fill guy as well)

disclaimer: NEVER intentionally and significantly OVERFILL AL TANKS!!!! Very BAD idea

Mike

 

[nessum]

I don't think any shops in my area fill in a water bath.
I believe Transport Canada requires a viz on tanks once a year... but I maybe wrong. We will not fill a tank that is out of viz or hydro.
A recent regulation change here in Canada is that tanks must be stamped by transport Canada. A US DOT stamp is not suffcient. And now we cannot fill or inspect a tank without one.

 

[Blackwood]

P1*V1/T1 = P2*V2/T2

Pressure and volume can be any consistent units, but you must use Kelvin for temperature. K = C + 273 and C = (F-32)*(4/5)

It doesn't have to be Kelvin. You must use an Absolute Temperature (such as K or °R).

 

[android]

True, I forgot all about Rankin. But it won't work for C or F.

 

[rab]

OK, I just have to correct the °C to °F conversion given earlier:

°C = (°F - 32) * (5/9)

°F = °C * 9/5 + 32

Here are a couple sample temperatures to use: 20 °C = 68 °F; 37 °C = 98.6 °F

-Rob

 

[shooter226]

The DOT only has legal authority in matters of interstate commerce and it would be considered an infringement on state's rights if they did otherwise. So that paragraph is technically correct, although many states have adopted the same standards as the DOT, so filling an out of hydro tank could still violate state or local laws.

The issue of federal versus state jurisdiction and the potential for something to be used in interstate commerce has been a hot button issue in things like the legalization of marijuana for "personal" use. The feds maintain that marijuana grown for alledgely personal use has the potential to be used in interstate commerce and should be regulated by the federal government. They will further assert that allowing this exception would make enforcement of drug laws nearly impossible and would undermine the federal government's authority to regulate interstate commerce. States on the other hand will maintain that it's their right to legislate what happens within their borders and if interstate commerce is not directly involved, the feds need to butt out.

The same arguments extend to things like filling tanks as well. From a practical standpoint, if a shop fills a tank and it is then taken across state lines, it could be viewed as a violation of federal law. The DOT will in fact most likely make the assumption that the tank will cross state lines if a shop fills an out of hydro tank. Enforcement policies vary over time and from adminstration to adminstration.

Given the potential for all portable tanks to be taken across state lines, the average dive shop would have a hard time defending their actions to a DOT investigator if they filled an out of hydro tank unless they could demonstrate that they knew positively that the tank would not be leaving the state and/or unless the customer signed a waiver acknowledging that the tank could not be used in the course of interstate commerce or transported across state lines. But I doubt any shops are going to want to take that risk or go to that trouble.

I think it has to be transported for commercial purposes for this to apply.

 

[padiscubapro]

I don't think any shops in my area fill in a water bath.
I believe Transport Canada requires a viz on tanks once a year... but I maybe wrong. We will not fill a tank that is out of viz or hydro.
A recent regulation change here in Canada is that tanks must be stamped by transport Canada. A US DOT stamp is not suffcient. And now we cannot fill or inspect a tank without one.

Not true.. Whether or not a US dot (or icc) stamp is acceptable depends on the date of manufactureof the cylinder.

(b) in use in Canada before January 1, 1993, was authorized for continued use under sections 7.32 and 8.4.2 of the “Transportation of Dangerous Goods Regulations” in effect on January 1, 2001, and the conditions in those sections are complied with; or

manufactured before January 1, 1993 in accordance with a specification for cylinders set out in 49 CFR and has displayed on it requalification marks as required by CSA B339 or 49 CFR, except a cylinder manufactured in accordance with