"Overfilling" faber lp 85,95

[DA Aquamaster]

Well...since HH's engineering and ethics lesson had no effect, how about a simple cost benefit analysis.

1) Benefit of overfilling a tank to get several more cu ft stuffed into it = a few more minutes bottom time.

Potential cost of overfilling a tank if it blows up in your face = a lot less bottom time because you are dead or maimed.

2) Benefit of using a larger tank in the first place = a few more minutes bottom time.

Cost of using a large tank in the first place = a bit more money in some cases and a bit more weight to carry to and from the boat.

Which case makes more sense to you?

What kills me is that some of the same people that go on and on waxing poetic about "potential failure points", "accident analysis", etc, etc, and prostelatize about their superior training and philosophy and the benefits they have on reducing the risks of technical diving to an absolute minimum are often the same divers who go on an on about the benefits of "cave fills", overfills, etc. and recommend that LP tanks be pushed to illegal and potentially hazardous limits.

They apparently see no contradiction in pushing safety to the extreme regarding skills, equipment and configuration on one hand and being the diving equivalent of a crash test dummy on the other by condoning and engaging in the practice of filling a tank with a 2400 psi service pressure to at or near it's hydro test limit.

Can anybody spell H-Y-P-O-C-R-I-T?

 

[mech]

So I guess asking legitmate questions that are yet to be answered makes me a hypocrit?
Ok...that's a reach I admit it .
I did see the chart.
I do have an engineering background with NDT and DT in it.
What I didn't see was some one posting proven facts,which is not to much to ask for.
I also said I find it wise to error on the safety side.
The last thing I like to do is argue or snipe so please don't take this reply in a negative manner.
Good day.
Andy

 

[Leadking]

The main issue seems to be that no one seems to understand that from the ground up European cylinders and U.S. cylinders are not the same cylinder with different stampings. The best place to go is to Faber's website www.divefaber and look at the manufacturing specifications for cylinders in different regulatory enviroments. What seems from the outward appearance, the same, is not the same. I don't want to wear a dry hydro on my back hoping everything will hold together. Dive safe!

 

[COVCI]

The main issue seems to be that no one seems to understand that from the ground up European cylinders and U.S. cylinders are not the same cylinder with different stampings. The best place to go is to Faber's website www.divefaber and look at the manufacturing specifications for cylinders in different regulatory enviroments. What seems from the outward appearance, the same, is not the same. I don't want to wear a dry hydro on my back hoping everything will hold together. Dive safe!

No matter how many times you tell them....

My final response is: "If you want to fill them like you "think" they do in Europe...move to Europe!"

Chris

 

[mempilot]

I'll be the devils advocate here. The US DOT standards are quite a bit more conservative than the European counterpart. How many Faber tanks are exploding every decade, let alone every year? I've done a search and can't find any. What I can find are AL80's and AL40's that have exploded. That being said, the Faber tanks made for European sale and the tanks sold to OMS are the same in property. The tanks are certified under slightly different conditions which shows up in the slightly different volume ratings. The requirements are also slightly different.

An OMS 98 rated at 2640 psi that is filled to 3000 psi is overfilled by 13.5%. The tank is hydro tested to 4000 psi after 5 years. At hydro, the tank is overfilled by 52%. I wouldn't condone overfilling the tank after the first hydro, but you guys are really overreacting about overfilling within the first hydro. If there was a huge risk of these tanks blowing with a 13.5% overfill, then I doubt the DOT would allow burst disks that exceed the 'risk' pressure, let alone hydro pressure.

I also wouldn't condone fast filling a 98 steel to 3000. Steel is quite a bit more accepting of expansion than an aluminum tank. I would never overfill an AL tank.

Anyway, find some statistics that back up your theory of being unsafe. Otherwise, it's just an opinion which we are all entitled to have. As for being responsible for what happens with the tank 3-4 owner from now is ridiculous. If you ran your Jeep through it's paces hauling your gear back through the trails every weekend to get to the best sink hole, are you responsible for the 3rd owner that drives it 80 mph down the highway when the steering linkage breaks and it kills him? Come on.

 

[Tom Winters]

Wow - none of you guys want to ever get on my boat when we have it loaded with jacked-up LP steels. I guess any day now I'm going to create a new deep water trench off Boca Raton.
For the record, I LOVE those LP 85's - with a cooled 3500 psi fill, you have 113 cubic feet in there. But I just can't seem to give up my LP 121's with 160 cubic feet at 3500psi. Maybe I'll have to start wearing a titanium toe tag when I'm near the bombs.
So now I have dived through the years where the steel 72 were the standard tank until they were eased aside in favor of the aluminum 80 and now we're back to steel again. I know guys who routinely overpumped their aluminum 80's to a standard 4000 psi, but I was never comfortable with that practice after seeing too many 80's fail their annual VIP's due to internal corrosion. I guess they were good about VIP'ing their tanks every few months because after 20 years of doing it, they still have not blown up Oahu. Or maybe they did and the government covered it up.
These discussions of overpumping remind me of the computer boards where people go on about overclocking their CPU's.
Maybe I should redesignate the boat as a B-52 carrying a full payload?
It's a good thing that there are NO dive shops down here who overpump tanks. It's a terrible, reprehensible practice, and I'm glad they protect the world from maniacs like me.

 

[babar]

Bottom line:
Is there a real difference between a PST LP-95 and an E8-119? No attacks, please. I just ordered the 119's and am not looking to overfill them. I would just like to know.

Babar

 

[Bobby]

Wow - none of you guys want to ever get on my boat when we have it loaded with jacked-up LP steels. I guess any day now I'm going to create a new deep water trench off Boca Raton.
For the record, I LOVE those LP 85's - with a cooled 3500 psi fill, you have 113 cubic feet in there. But I just can't seem to give up my LP 121's with 160 cubic feet at 3500psi. Maybe I'll have to start wearing a titanium toe tag when I'm near the bombs.
So now I have dived through the years where the steel 72 were the standard tank until they were eased aside in favor of the aluminum 80 and now we're back to steel again. I know guys who routinely overpumped their aluminum 80's to a standard 4000 psi, but I was never comfortable with that practice after seeing too many 80's fail their annual VIP's due to internal corrosion. I guess they were good about VIP'ing their tanks every few months because after 20 years of doing it, they still have not blown up Oahu. Or maybe they did and the government covered it up.
These discussions of overpumping remind me of the computer boards where people go on about overclocking their CPU's.
Maybe I should redesignate the boat as a B-52 carrying a full payload?
It's a good thing that there are NO dive shops down here who overpump tanks. It's a terrible, reprehensible practice, and I'm glad they protect the world from maniacs like me.

Tom,
Dinosaurs like us that are time bombs waiting to blow should not influence the youngins. Just cause we lived through the 72's & I agree with you on the Al 80's just proves we have no idea what is going on. Where you at in Boca I might have to stop by & add to your explosive arrsonal some time

Bobby

 

[jonnythan]

I'll ask a question I thought I asked but guess I didn't.

Does anyone have any links to any stories of PST or Faber LP tanks blowing up, whether due to overfilling or otherwise? The only tanks I've seen articles about were Al80's with the old alloy or really really old small steel tanks in very bad shape that would have failed a visual years before.

 

[DA Aquamaster]

An OMS 98 rated at 2640 psi that is filled to 3000 psi is overfilled by 13.5%. The tank is hydro tested to 4000 psi after 5 years. At hydro, the tank is overfilled by 52%.

The service pressure for an OMS 98 is 2400 psi, not 2640 psi. 2640 psi represents a 10% overfill. So a 3000 psi fill is a 25% overfill, not a 13.5% overfill and divers who are considering or suggesting 3500 psi are considering a 46% overfill.

The hydro test pressure is 5/3rds of the service pressure, or a 60% "overfill" at 4000 psi. The critical difference being that the "fill" is done with water with no heating involved and the pressure is only maintained for a few seconds.

I wouldn't condone overfilling the tank after the first hydro, but you guys are really overreacting about overfilling within the first hydro. If there was a huge risk of these tanks blowing with a 13.5% overfill, then I doubt the DOT would allow burst disks that exceed the 'risk' pressure, let alone hydro pressure.

Asked and answered but to reinterate, we are talking about a 25% overfill not a 13.5% overfill. I guess it bothers me that you are pushing an argument that may be read by other divers and taken as fact when you don't even have the basic facts straight to begin with.

Burst disc assemblies are commonly available with ratings up to 5000psi, but that does not mean it's ok to use a burst disc with the wrong capacity in your valve. It's common, or at least used to be common in the pre-cave fill era, to use a burst disc capacity of approx 133% of the service pressure to ensure the tank would vent before exploding in a fire and to ensure things vented well before the hydro test pressure. Now it is all too common to use a burst disc with an excessive capacity or to stack two burst discs. Neither practice is safe nor legal.

Anyway, find some statistics that back up your theory of being unsafe. Otherwise, it's just an opinion which we are all entitled to have.

Everybody has an opinion, but it is a logical fallacy to assume that an opinion is right just because everyone has one or because that opinion is commonly held. At the risk of again offending someone who may think I am talking specifically about them when I'm not, if you came from a certain training orientation and had a dive buddy with unsafe practices or equipment, the conventional wisdom would be to avoid them as they present a safety hazard by violating commonly accepted standards.

The same argument can and should be made about divers with illegal overfills. Those overfills violate not only the law but the accepted industry standards and are perceived to pose a threat of elevated risk to everyone with in range of the exploding tank (ie: everyone on the boat or in the dive shop.)

You can have and express any opinion you want, but your right to put that opinion into action stops the moment your action potentially infringes on the rights of others. The burden of proof is consequently not on adherants to accepted standards to prove that a threat exists if those standards are violated, but rather on the person violating those standards to show that an increase in risk to others does not exist. Adhering to rules and respecting the rights of others is just a matter of social contract - if you want to live in and be accepted by a society, it's just part of the deal.