tank size and pressure

[W W Meixner]

Its not 150% over WP, its 50% over WP.

It is 150% OF the WP however, but thats a big difference and its not what you said.

Noted...thank you...correction made...

 

[BRT]

Victor...

Hydro/re-hydro is a practise/process/procedure which is manufacturer acceptable...conducted by trained professionals...using specialized equipment with built-in safety factors...for very short periods of time...filling a LP cylinder to 200% of its WP and diving with it is not acceptable by any scuba cylinder or scuba cylinder valve manufacturer...there is a difference between a service ''test''...and daily practical application...

Accident case history has already been provided on SB regarding this subject...suggest looking through the archives...

W...

Ha ha. Accident case history! One video of a tank that was nearly rusted in two exploding and not hurting anyone. It was assumed to be in hydro and vis because "they wouldn't fill it if it wasn't". Got anything real?

 

[victorzamora]

No can do. I can, however, calculate and post the amount of gas predicted by the van der Waals equation.

Fair enough!

Good thing I've been geeking out with a spreadsheet earlier, since that saved me about a ton of time. Using the most recent values for the van der Waals constants that I have available (CRC Handbook of Chemistry and Physics, 63rd Edition, 1982-1983) I get:

Now, @tbone1004 's post with the compressibility numbers made me a little concerned. Because although he'd gotten them from Wikipedia, Wikipedia had lifted those numbers from Perry's Handbook of Chemical Engineering which is sort of the bible for data like that.

It's interesting how different the two sets of values are. For example, EANx at 242bar (the most relevant to me) shows 4032L vs 3870L. That's a difference of ~4.2%, which is pretty huge.

 

[W W Meixner]

Ha ha. Accident case history! One video of a tank that was nearly rusted in two exploding and not hurting anyone. It was assumed to be in hydro and vis because "they wouldn't fill it if it wasn't". Got anything real?

BRT...

There's more than that...we went through this less than a year ago...check PSI's web site...as a primary cylinder service trainer...they have the most complete reported accident registry...how accurate it is is anybodys guess...

Unfortunately...most incidents are never reported unless there are injuries and/or fatalities...and like so many investigations relating to ''scuba''...and who is actually conducting the investigation...wrong conclusions are more common than correct conclusions...as lack of industry knowledge...fails to detect ''root causes''...

Did the cylinder fail because...it was over-filled...it was not O2 cleaned...it was no longer serviceable...the fill station operator was not trained...or any combination of these or others...???

W...

 

[BRT]

BRT...

There's more than that...we went through this less than a year ago...check PSI's web site...as a primary cylinder service trainer...they have the most complete reported accident registry...how accurate it is is anybodys guess...

Unfortunately...most incidents are never reported unless there are injuries and/or fatalities...and like so many investigations relating to ''scuba''...and who is actually conducting the investigation...wrong conclusions are more common than correct conclusions...as lack of industry knowledge...fails to detect ''root causes''...

Did the cylinder fail because...it was over-filled...it was not O2 cleaned...it was no longer serviceable...the fill station operator was not trained...or any combination of these or others...???

W...

Post some examples, if you can.

 

[dead dog]

Believe me, you can afford flowers for all the people who ever died from exploding steel scuba tanks that were in hydro and vis.

Yes, I can. It only takes one to die to make my point. Live on.

 

[BRT]

Is this where I send the flowers?

You are slow too. Steel cylinder, in hydro and vis. Send the whole flower shop to anybody killed by one. It isn't going to cost you anything.

 

[NAM001]

Firstly, 3600psi is not 200% of the Working Pressure, it's 136%-150% depending on your tilt.

Secondly, I'm not talking about "safe during hydro", I'm talking about representatives from Faber saying that it's fine to cave fill their LP85s, LP108s, and LP121s, among others.

I know of no reps of faber, or any maker, that will say its OK to over fill. Further I dont know of any one that will say that faber said it was OK. No one who is subject to professional liability would.

What is being said is that there is an abundance of over protection regarding this issue.. Not only is this an opinion it is one that has been over the years been proven safe to do after thousands of over fills have been done with out incident. Not every thing labeled bad is really bad. I dont know if my tanks have really ever seen a legit fill. the LP's I use are always filled to min 3000. or at least cool to 3000. They have always passed hydro with the same results of a new tank.when it comes to recovery specs. Its very much like driving 70 in a 60 zone. Our social safety structure has been for a long time been based on the worst case situations. Those situations seldom exist. If that were not true superman costumes would not have a warning tag on it that says this costume does not allow the wearer to fly. All our kids would be kid napped if mothers did not drive them to school and pick them up.

Let me ask you a question regarding your car tiers.. how full do you fill them. per the psi on the tire or the psi on the car frame or the psi in the owners manual. And then what do you do when you replace the tires with a brand that is not the original issue? Why would a car maker say use a tire that has a 36 psi stamp on it and then say fill to 32 psi. It certainly is not for safety, Its probably for smoothness of ride. Quite often the rear tires are at one inflation and the front are at another. And that probably has more to do with tire wear for a given weight load than safety. Although you can over inflate your tires and get better millage but as a wear cost.

 

[W W Meixner]

You may think it is beat to death but still you appear to fill tanks to not exceed stamped WP. AND IT IS ALLOWED TO BE DONE. Your proceedure is the shops policy and not based on actual regulation either. If that is not understood then further converstaon is moot. So long as a tank at 70 degrees F is 3000 or less it is not over filled. Granted that has little to do with the over all topic but it does to yoru comment. You also refer to slow fills as a means to avoid this issue. I have yet to find a shop that has any tank fill demand that does that. they can not afford to. So you water bath them to cool them down so as not to be filling a 130F sun heated tank and instead filling a 80F tank. To many tanks get 2 minute fills and they are out the door using the if you cant wait you get what you get ligic. They hit the 70F water and the psi drops to something far below WP. Lets see 5psi per degree adn a 120 degree tank filled and heated by the fill to 160 is 90 degrees over base temp and that is 450 psi. That 160F tank can be filled to 3450 and not violate any rules regarding the WP 3000 psi aspect. Ill repeat ,,,, a 3450 fill in those conditions is not an over fill.

KWS...

I thought we were done...nothing at all to do with individual shop policy...

''AND IT IS ALLOWED TO BE DONE''...your words...please post the documents...

I've shown you mine...please show me yours...

W...

 

[tursiops]

It is considerably more dangerous for me to drive to the dive shop to get my steel cylinder overfilled, than it is for me to overfill that cylinder.