Air Fill Protocol

[Superlyte27]

I MUST BE IGNORANT HERE OR JUST DO NOT RECALL THE TERM sorry for the caps

what is turn presure??? perhaps you have some text to help me understand the term? thanks

Let the record reflect that this guy did NOT pass his Intro to Cave class

 

[Paulmal]

The marking on the tank only matter If you are transporting them on public roads. If you fill at the dive sight you can do whatever you want within reason. At the end of the day do what you think is right, and I'll do the same. I will overfill an Al tank by 300 psi or so to allow for cooling because of the properties of Al but steels are a totally different story.

 

[DA Aquamaster]

Just have to clear something up. When you say "...referencing sections that refer to actual hazardous materials rather than gases such as air and nitrox...", I assume you're referring to my post where I said:



You may disagree, but Title 49 is pretty clear. A non-flammable, non-poisonous gas (like air) at a pressure greater than 29 psig is defined as a hazardous material. You do "...have to pay close attention to the sections and sub sections you are in to properly interpret the meaning and interpretation of a specific regulation."

My point is that a full scuba tank may seem pretty benign, but we need to keep in mind that there's a lot of potential energy cooped up in there... Enough that the DOT felt it necessary to set regulations about transporting them.

The Defense Logistics Agency has some guidelines about filling compressed gas cylinders as well.

DoD 4145.19-R-2

Tim

Yes, compressed air is considered hazardous, but the requirements for compressed air tanks and tanks used to carry hazardous materials are different, with the latter being more restrictive.

---------- Post Merged at 04:59 PM ---------- Previous Post was at 04:57 PM ----------

Turn pressure is part of a gas management plan for advanced diving. Typically rule of thirds, one third of your gas for the decent, one third for the assent, and the last third for emergencies. ie you buddy looses all his gas due to a valve failure. So on LP steels you start your dive with 3600 psi you turn at 2400 psi and get out of the water with 1200 psi.

Exactly - you turn when you breathe your tanks down to "full".

 

[Diver Tim]

Yes, compressed air is considered hazardous, but the requirements for compressed air tanks and tanks used to carry hazardous materials are different, with the latter being more restrictive.

"...compressed air tanks and tanks used to carry hazardous materials..."

Compressed air IS a hazardous material, and the part I quoted DOES applies to transporting compressed air. There are additional restrictions if the compressed gas you're transporting happens to have another hazard class as well.

The marking on the tank only matter If you are transporting them on public roads.

True, but it still seems to me like a pretty good rule of thumb.

If you look at the regulation, it basically says that it's acceptable for the pressure in a tank with a 3000 psi service pressure to be up to 3750 psi at 130F. That IMPLIES that if the air in the tank is between 70 and 130F, you can fill to a pressure higher than 3000 psig, as long as if you were to heat the tank to 130F, the pressure wouldn't exceed 3750. The DLA manual I linked (and the DOD is actually pretty conservative when it comes to industrial safety) says if the fill temp is above 70F, you could add 5 psi per degree above 70. It also says not to expose tanks to temperatures above 130F.

I'm not saying NOT to fill tanks past their service pressure to account for cooling. I'm just advocating an understanding of the risks involved and regulations regarding transport.

Tim

 

[NAM001]

I REALLY FEEL FOOLINSH NOW I just got the meaning ofn the comment of turn presure that was stamped onthe tank. I knew what turn presure was but did not catch the sarcasm in the usage or make the connection to the tank fill presure. I am with you now.

Turn pressure is part of a gas management plan for advanced diving. Typically rule of thirds, one third of your gas for the decent, one third for the assent, and the last third for emergencies. ie you buddy looses all his gas due to a valve failure. So on LP steels you start your dive with 3600 psi you turn at 2400 psi and get out of the water with 1200 psi.

 

[Bob DBF]

I am in the habit of checking my fills with a tank checker at the shop. I almost always drop off a load of 3-4 tanks and pick them up later when cool. A few times some have been low and I ask for a top off even it is just 100lbs. They guys are not stupid, pretty soon they learn to anticipate my checking and I find 3100-3200 in the tanks by magic.

Just a matter of training the LDS. My LDS rarely does drop off and pick up later and I don't need two trips for one fill so it's fill and go. I knew who did the fill and I record the tank pressure at the dive site. Bad fills and the followup private discussion with the offending tank monkey have managed to get my tanks filled properly, what they do on others is not my concern. People will take pride in their work if someone is noticing and thanks them for a good job.



Bob
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I may be old, but I’m not dead yet.

 

[wedivebc]

A couple of things I learned from owning a dive shop. Water baths are useless with aluminum tanks the walls are too thick for any meaningful heat transfer and the water just keeps your floor wet.

If you leave a pressure gauge and allow the customer to check it if they want no one will ever complain about tank fills, as long as you don't complain if they ask for a top up.

Filling an AL80 to 3300 will usually cool to a solid 3000 and no one should ever complain about that.

The guy who ran the charter I used once replied when a customer complained about an underfilled tank, "don't breath so much"

 

[Paulmal]

A couple of things I learned from owning a dive shop. Water baths are useless with aluminum tanks the walls are too thick for any meaningful heat transfer and the water just keeps your floor wet.

If you leave a pressure gauge and allow the customer to check it if they want no one will ever complain about tank fills, as long as you don't complain if they ask for a top up.

Filling an AL80 to 3300 will usually cool to a solid 3000 and no one should ever complain about that.

The guy who ran the charter I used once replied when a customer complained about an underfilled tank, "don't breath so much"

When I worked as a tank monkey I filled Al tanks to 3300 too, we had an analyzer and a pressure gauge by the tank pick up area, I told all the customers I am good not perfect please check your tanks for pressure and mix, if they wanted a top off I would happily top their tanks off. Simple steps can help alot because it makes people think about their fills.
I have not had anyone complain about an overfill guess it has to do with the area I dive. If you have problem with how the fills are done in your area, get your own fill station, as most dive shops loose money on fills.

 

[leabre]

I thought that was FL cave humor . . .

Ha ha, so did I! But I wonder if its just the cave divers that would see the humor! I thought it funny, actually, quite funny! A good mood-litener to the serious tone of the thread!