Cave Fills on LP tanks

[northernone]

Probably should use more hose clamps.

Reckon that's #24 or #36 line?

How many PSI above 3000psi per band?

It's important to remember when a tank "fails" hydro @xxxx psi, it isn't a catastrophic failure blowing up the place, it's swollen beyond specs. Safe to say I think those might have failed.

 

[victorzamora]

My question was what is the justification for recommending someone gets lp85s and overfills them instead of simply getting 100s.

...um, we would cave fill the 108s too. So comparing a CF 85 to a 2650 filled 108 doesn't make sense.

I guess I should've explained a little more, but: I was answering the question on why one would justify LP85s and cave-fills over an FX100. Well: LP85s hold 15% more gas and do better in SM for many/most people.

A frequent rebuttal I've heard is "Why not just carry bigger tanks?" Well, LP108s with a 2640psi fill hold less gas than a cave-filled LP85 and are inarguably larger. So if you want 110ish cubic feet per tank, LP85s with a cave fill make a lot of sense....certainly more than lp108s at 2640psi, imo.

I dive cave-filled steel mains exclusively, and don't see any reason to not get cave fills in steels. I was initially a little hesitant to pump LP tanks to 3600psi, but getting a look at the fleet of rental tanks cave shops have that get pumped up to 3600psi with WAY more frequency than I'd ever fill my own certainly settled that.​

 

[Charles2]

I might mention that on a chain or a rope the minimum breaking strength is only valid while the item is new. I have had someone I trust tell me that a steel 72 will take north of 7000#.

The DOT 3AL specification for an AL80 with a working pressure of 3000 psi requires a minimum burst pressure of 7500 psi.

 

[BRT]

Reckon that's #24 or #36 line?
View attachment 460861
How many PSI above 3000psi per band?
View attachment 460862

It's important to remember when a tank "fails" hydro @xxxx psi, it isn't a catastrophic failure blowing up the place, it's swollen beyond specs. Safe to say I think those might have failed.

That wooden pipe is amazing stuff. I have seen it over 50 years old, maybe 75 years, still working. The wood swells and seals and the bands hold the pressure.

I should measure and then fill an AL80 and an HP100. I'll bet they both swell measurably.

 

[Diving Dubai]

I love the hypocrisy from the cave/etc community. They’ll get bent out of shape about supposed “additional failure points” and additional d-rings, but are happy to blow their tanks up beyond specs because they know better.

I could go back to my text books and find the relevant graph and data but it would be pointless as full cave trumps a metallurgy degree

 

[Caveeagle]

I love the hypocrisy from the cave/etc community. They’ll get bent out of shape about supposed “additional failure points” and additional d-rings, but are happy to blow their tanks up beyond specs because they know better.

I could go back to my text books and find the relevant graph and data but it would be pointless as full cave trumps a metallurgy degree

Nice job of illustrating a straw man fallacy.

I started diving in caves in the early 90's and have never had anyone get "bent out of shape" over an extra D ring. Sure there are the GUE/DIR advocates that promote uniformity, but they are far from being up in anyone's grill about it. If you don't like the DIR groove, they are pretty easy to avoid.

The comparison you are trying to make does not hold water!

 

[Diving Dubai]

Nice job of illustrating a straw man fallacy.

The D-ring comment was me being sarcastic and factious - obviously lost on you.

 

[Caveeagle]

The D-ring comment was me being sarcastic and factious - obviously lost on you.

Not lost on me one bit, but it was your best example of why you label the entire "cave community" as hypocrites. ...or perhaps we should not take you seriously on that point either. ?

Did some cave diver make fun of your cave snorkel?

 

[PfcAJ]

I love the hypocrisy from the cave/etc community. They’ll get bent out of shape about supposed “additional failure points” and additional d-rings, but are happy to blow their tanks up beyond specs because they know better.

I could go back to my text books and find the relevant graph and data but it would be pointless as full cave trumps a metallurgy degree

Again, how many data points do you need before accepting that a 2640psi working pressure doesn’t reflect reality?

 

[Diver-Drex]

@Michael Guerrero - You’re just not correct here. The CFR does apply to SCUBA cylinders.
- 29 CFR 1910.1200 classifies all pressurized gasses as hazard substances.
- 39 CFR 183.115 specifies compressed air over 40psi to be a hazardous substance.
- 49 CFR 180.205 requires over pressure devices specifically for 3AA and 3AL cylinders.
- CGA Pam S-1.1 requires an over pressure device.
- 49 CFR 178, 37 covers specifications for 3AA cylinders and 47 covers 3AL cylinders. The service pressure marking is required, it is not a suggestion. It is the maximum pressure allowed in that cylinder at 70 degrees F.
- There are also OSHA regulations, 29 CFR 1910.10, around an employer’s responsibilities. These include visual inspection and the use of over pressure relief. An employer allowing, directing or exposing employees to improperly handled or stored cylinders is in violation. Filling beyond the service pressure is improper handling.
This goes on and on and on...
And to put this to rest...
- 49 CFR 173.302 specifies what is required for the maximum allowed 10% overfill of a steel cylinder. Along with the hydro test requirements it specifies a burst disk is required.

The legality isn’t up for debate. This is from a post I made back in February. I am not arguing that the law makes sense just that it exists.

So recommending someone get lo cylinders and over fill them is:
1. Bad advice if you don’t have a source for the fills.
2. Advice to do something that is illegal.

I have four lp85s and they are my preferred cylinders. If I need more gas then I have a set of 100s. I fully understand there are several of you doing dives that require a s$@t ton of gas. You are big boys and can make your own decisions.

@Caveeagle - I didn’t say cylinders were exploding. I said we don’t know when they will. Can we agree to not give the general diving community the green light to find out?