The perils of owning LP tanks in the Midwest

[MrVegas]

This is a pretty entertaining thread. I have accumulated some LP steel tanks in the Midwest that I really like, and they seem to get randomly filled to anywhere between about 1900psi and 3000psi. It doesn't matter much for the type of diving I do, so I don't complain. I suspect that people typically just fill them hot to whatever is written on the side of the tank (e.g., 2400 or 2250) without regard to a + sign and don't top them off. If an owner or diver that is used to the tanks fills them, there will be a bigger fill, and I have never had someone complain if I have tested the tank and asked for a top off (always worth it to check and ask).

If you own a shop, what are you supposed to say to an employee, though? You can't really tell them -- OK I know that manufacturer said 2250 or 2400 (or 2640), but you can fill them to 3000 or 3600.

As to why to buy LP tanks? People with HP tanks complain they don't get 3442 anyway, and, if you're lucky, you can get a good deal on used LP tanks.

 

[Marie13]

My first LPs were 50s. I got them for recreational diving due to my knees. Then with cavern/intro to cave class coming up, I decided to get 85s. They trimmed out on me so much better than my HP80s. It’s worth the extra trouble to me to get a better fill. For the mine diving, I definitely want a bit of an overfill.

At the new shop where I got the good fills, I’m dealing with the owner.

 

[rx7diver]

@Marie13 ,

I don't know if you've considered this, but if you have two pairs of LP 85's and access to a compressor that delivers oxygen-compatible air, then supplying yourself with EAN32 (to whatever reasonable psig) can be done quite easily with many fewer inconvenient, long-distance, round-trip drives to the custom EAN-blending dive shop!

Of course, there is the cost/maintenance of that second pair of LP 85's.

And there is the access to a compressor that generates free oxygen-compatible air.

rx7diver

 

[Marie13]

@Marie13 ,

I don't know if you've considered this, but if you have two pairs of LP 85's and access to a compressor that delivers oxygen-compatible air, then supplying yourself with EAN32 (to whatever reasonable psig) can be done quite easily with many fewer inconvenient, long-distance, round-trip drives to the custom EAN-blending dive shop!

Of course, there is the cost/maintenance of that second pair of LP 85's.

And there is the access to a compressor that generates free oxygen-compatible air.

rx7diver

Don’t know anyone local with their own compressor. And getting my own is NOT an option (live in a small apartment).

 

[divezonescuba]

We are looking into renting a small storage unit to keep a small compressor at our condo rental property when we go on dive trips there.

We would have to be able to put a 220 v / 50 amp breaker in the panel. Most residential electrical panels are built to do that by just changing the breaker. We did it at home in the garage prior to opening up the shop and ran our medium sized compressor in there.

it will also keep dive gear that we don’t want to keep carting back and forth.

 

[rjack321]

We are looking into renting a small storage unit to keep a small compressor at our condo rental property when we go on dive trips there.

We would have to be able to put a 220 v / 50 amp breaker in the panel. Most residential electrical panels are built to do that by just changing the breaker. We did it at home in the garage prior to opening up the shop and ran our medium sized compressor in there.

it will also keep dive gear that we don’t want to keep carting back and forth.

How big is small?
The issue with 3cfm units is that by the time you get back from a day's diving you don't want to spend 2 to 4 hours refilling a whole suite of tanks

A 50 amp breaker would not be a small compressor though.

 

[BRT]

I won't belabor trying to make my point, but you're not following what I'm saying. Okay, one more try. "Against the law" doesn't have a legal meaning in itself. Laws that no one has any intention of enforcing (or that can't be enforced as a practical matter) can be enacted, but they have no practical effect. If DOT officials give you a mystified look when you ask about dive shops, does the regulation really apply to dive shops? I think of the saying about "If a tree falls in a forest ...." I really have no knowledge of how the DOT views dive shops--this is just me spouting off on a hypothetical--but IF it's true they don't care or have never given it any thought, then I think the regulation as it might apply to dive shops is null.



Right. And that was what I was getting at in the second part of my comment: "They might also want to avoid overfilling to avoid potential liability to someone injured as a result (and a lawyer could attempt to use a violation of the CFRs as evidence of best practice)."

But those are two different concepts.

Breaking the law wouldn't scare me. I could probably pay the fine. The legal liability is unlimited. That scares me. I pump my LP's to 3900 hot.

 

[NAM001]

The argument always comes up regarding whether CFR's apply to all or only commerce transportation. Any more it makes no difference whether you comply with the law or not when the insurance companies are involved and state condition of coverage is to comply with CFR"s in your business. Business = commerce. There are loopholes to everything. such as the transport of tanks rentals or training equipment. I have heard talk of if total tanks are 1000$ value it falls into commerce transportation ( stops private people from doing formal shipments) as a side step to decide between personal movements or professional movements of hazmat vessels. scuba tanks are hazmat. What is the HASMAT you ask,,,,, it is the pressure in the vessel not the vessel. I believe it is generally accepted if movements are involved in a paid service it is considered a; movement of commerce. The argument is that a scuba class is a paid service. yet a student can move all the tanks to a dive site because they are not in a paid position. Then the argument ARISES that the student is acting as an agent ( an untrained one at that) of the commerce shop. The debate never ends. At the end of the day it is like using cell phones . NO one enforces it. It only becomes an issue when there is an accident or property is damaged and a JURY hears the case. Then the LAWS AND REGS / CFR'S compliance is checked to determine liability. The most retarded one I usually come across is that is illegal to fill a al80 past 3000 psi. Under the right conditions it is illegal to fill an AL 80 to 2900 psi. You can always be a jerk if you choose as you leave their shop for good and ask to see the fill station operators training records for hazmat and the specific compressor system training being used. YEA THATS A CFR REQUIREMENT ALSO. Bottom line is it is their shop, sometiimes it is fun to impress that they are not the only one that claims to know the CFR's . Want more fun ask when the last time all of their nitrox system components were O2 cleaned.

 

[Divin'Papaw]

We seem to get all bent out of shape about fill pressure. A tank is just a vessel for breathing gas. What matters is how much gas is in the vessel and is it enough to do the dive I plan plus a safety margin. What kind of a fill (overfilled LP, underfilled HP, overfilled HP, underfilled LP) is just an academic exercise. Pressure is secondary to the number of cubic feet (or liter) in the tank.

 

[-JD-]

We seem to get all bent out of shape about fill pressure. A tank is just a vessel for breathing gas. What matters is how much gas is in the vessel and is it enough to do the dive I plan plus a safety margin. What kind of a fill (overfilled LP, underfilled HP, overfilled HP, underfilled LP) is just an academic exercise. Pressure is secondary to the number of cubic feet (or liter) in the tank.

Exaggerated counterpoint: If I take my 60 gal. shop compressor tank diving, I can have about 80 cubic feet (at compressor-nominal 150psi or 120 if I jack it to rated max of 225psi) to do a nice reef bimble. Unfortunately, that doesn't really work on a number of levels.

Caring/competent humans tend to select things for efficiency. For dive cylinders, that is going to be a series of tradeoffs between gas capacity, buoyancy characteristics, cost, weight, size, durability, "fillability", etc. And when more utility can be obtained by cramming more gas in while holding the other factors the same, well that is more efficient ...

At least in my experience, "we" also tend to make personal evaluations of risk profiles for certain circumstances that may be less or even more conservative than those governmentally dictated (typically in a Lowest Common Denominator sort of analysis i.e. for folks who are anti-Wobegonean)

In my mind the "reasonable overfill" is very akin to the fact that (barring jams or adverse conditions) the majority of highway traffic seems to consistently travel at a speed 5-15mph over the posted speed limit. It is simply more time efficient. (Which is why we use vehicles of all sorts instead of walking everywhere.)