Etiquette if the shop doesn't fill the tank completely

[Divin'Papaw]

I have a different take on fills than most. I see a fill as a cost of allowing me to do the next dive. I view it as a fixed cost for that dive, not "did they fill my tank to its rated capacity". As long as I can do the next dive I have planned without being gas limited, I'm happy and won't request a top off.

For the shops I use here in Florida I have rarely had any issues. They typically fill my tanks to rated capacity and frequently 10-15% more. The last time I can recall having to ask for a top off was probably 4-5 years ago. In that instance the shop was more than happy to top off my tanks. In that instance I had brought in a combination of LP85 and HP100 tanks and they had inadvertently filled them all to 3000 psi which is their standard fill for LP tanks. While that is a solid fill for a LP85, it was definitely light in my HP100s. They resolved the issue quickly and without any drama.

 

[wetb4igetinthewater]

I just drop by for a quick fill. Then I take the tanks with me, run errands (Home Depot is close to the shop where I get fills) and then come by to get it topped off. Sometimes they tell me to leave the cylinders there, but I make sure that they give a hot fill before I leave. It has never been an issue. Did get a cave fill once, where I spent an a hour and a half at Edmonds Underwater Park, a fairly shallow site at depths of 30 to 40 feet. But that manager is no longer there.

 

[Tracy]

I've seen this a few times around here. A shop will spend insane amounts of money on compressor(s) and boosters that decades of fills could never recoup the capital outlay. After maintenance is factored in I'm not sure they will ever break even.

That is usually a shop that wants to break into the HUGE money of tech diving.
They buy new equipment based on the recommendation of a salesman, not something that would actually make sense for what they are doing.

 

[spool]

I've seen this a few times around here. A shop will spend insane amounts of money on compressor(s) and boosters that decades of fills could never recoup the capital outlay. After maintenance is factored in I'm not sure they will ever break even.

Well it's interesting how you'd capitalize that. Yes you can ask how many $5-10 fills until the compressor + maintenance breaks even, but on the other hand:

1) it's something that brings (forces) customers into your shop and they buy stuff or services

2) it's something without which you absolutely cannot operate a scuba shop
(it's the piece of capital equipment that most divers will not get on their own and be willing/able to service, that has air quality requirements that can't be met by a commercial compressor off the shelf even if it can do 5000 psi)

So is that cost of doing business? Like having to replace the carpet in your store every few years etc? hehehe

 

[spool]

I have tanks that have helium in them they are 8+ years old. I’ll analyze them before I use them, but they’ll be just fine until they’re empty.

And the analysis is basically for O2 content? I know HP / Steel needs to be tested for %O2 content after long term storage (some kind of chemical reaction that robs the O2), Aluminum does that have that.

I'd be curious there's any other risks like:
-reactions that introduce poisonous gasses like CO that the O2 sensor will not see
-reactions that mess with the mixtures (Helium is noble but anything else would be interesting)

If not, then my guess is this issue is mitigated with a well running Nitrox tester no matter how long you're stored.

 

[Kharon]

Yeah, only about $30k to buy and $500-$1000 per year to run and maintain. So basically no overhead.
Not saying you shouldn't get a full fill, but the entirely profit thing is hilarious.

OK - I've been educated. Sorry. So no profit. Still getting a short fill isn't acceptable. Maybe charge more and give complete fills.

 

[Superlyte27]

And the analysis is basically for O2 content? I know HP / Steel needs to be tested for %O2 content after long term storage (some kind of chemical reaction that robs the O2), Aluminum does that have that.

I'd be curious there's any other risks like:
-reactions that introduce poisonous gasses like CO that the O2 sensor will not see
-reactions that mess with the mixtures (Helium is noble but anything else would be interesting)

If not, then my guess is this issue is mitigated with a well running Nitrox tester no matter how long you're stored.

In a close bottle of aluminum or steel, there is no chemical reaction of Nitrogen, Helium and Oxygen that makes CO.

 

[Tracy]

And the analysis is basically for O2 content? I know HP / Steel needs to be tested for %O2 content after long term storage (some kind of chemical reaction that robs the O2), Aluminum does that have that.

You would only have that if the air was wet and it started forming rust. Dry air won't react with the tank.

I'd be curious there's any other risks like:
-reactions that introduce poisonous gasses like CO that the O2 sensor will not see
-reactions that mess with the mixtures (Helium is noble but anything else would be interesting)

If not, then my guess is this issue is mitigated with a well running Nitrox tester no matter how long you're stored.

There is no combustion happening in a stored tank to cause CO production.
In long term storage, the helium will actually stratify. I have seen it, a tank of 10/70 sitting upright for 5 years. If you analyze it without moving it, it will analyze as 100% helium. Pull it out and move it around, it will mix back up and analyze the same as when it was stored. It is kind of neat.

 

[Seaweed Doc]

Understood!

As far as the remote station set to 2700, will they leave it in the machine for a while so it gets up to stable / cool tank 2700? Or does it hit 2700 once and then you get 2500 or less?

It depends. Tanks are re-filled immediately after diving so they're ready for the next day. We often will top them off the next day.

 

[Seaweed Doc]

(Home Depot is close to the shop where I get fills)

That'd be the Bitter Lake (Aurora Ave. N.) Home Depot? I often kill time there as well.

(Or do all dive shops have Home Depots near by? I'm genuinely curious.)