Overfilling HP100 tanks

[fire_diver]

So I have scanned the forum and done all the searched and still want to ask. I have a HP100 and a compressor that will do 6000 psi. With the common practice of overfilling LP bottles to 3800 and over I ask why not HP? At a 10% overfill thats still only 3800.

As I understand it there is a different metal composition? And its more stress on regs but the same reg is used for LP overfilling so is anyone else pushing this envelope? My reg is a DIN Mk17

Look at the hydrostatic test pressures for tanks. Tanks are designed to withstand a minimum of 10,000 fills to test pressure. Do you really think put a few hundred over a standard fill is going to hurt it?

As for pumping an LP tank to 3800, I'll leave that up to the individual tnak owners but I wouldn't do it. Personal opinion. Some have been doing it for decades and never had a problem.

 

[climbr1]

Personally I dont think it would hurt, but I wanted someone to help me justify my reasoning
I am not an engineer

 

[N2DeepInAz]

My disclaimer: Just because you can, doesn't mean you should.

I have seen HP100's filled to 3800 after they've cooled down, in the winter time here in Az.

In the summer time here, there's no way would I fill a tank much beyond the service pressure simply due to the rapid expansion of the air due to the heat of our summers.

But people do questionable things...

 

[rjack321]

Personally I dont think it would hurt, but I wanted someone to help me justify my reasoning
I am not an engineer

6000psi is "gonna hurt"

hydro test pressure is only 5250, and exemption series tanks often struggle to pass that (unlike 2400psi 3aa tanks which almost never fail since they are quite overbuilt relative to their 4000psi test pressure)

 

[dtownsend2000]

Put the tank in a large bucket of cold water to get a good effective fill in the summer. As long as you keep them out of direct sunlight, 10% shouldn't hurt.

 

[fire_diver]

As far as usable gas while diving, it doesn't matter what the pressure is on the surface. If you "cold fill" a tank and then it heats up in the sun, (increasing the PSI) you then lose all that "gain" as soon as you get in the water and the tank cools down again.

 

[CAVDVR93538]

Also, how long do you want things to last? If you continually fill the tank beyond the rated capacity, the metal is getting compromised, the burst disc (ok you put in a stiffer one or doubled up) is going to be stressed and the hp seat in your regulator is going to suffer as well. All of these things are going to be affected by over pressuring your tank. The stress has to go somewhere and the weakest point will suffer the most.
I have seen hydro tanks with born dates in the 60's & 70's and still pass hydro. I've seen tank fail hydro with born dates in the 90's.
I agree with just because you can, doesn't mean you should. When good ole murphy decides to pay you a visit, it might not be at YOUR convience. 10% not so bad the HP tank is probably 3442 psi, so 10% would be around 3800 psi.
Why tempt fate? Stay within safety guide lines and your equipment and perhaps your life will be here for years to come!
My 2 cents!

 

[ajtoady]

Seems to me it is a foolish move for a few extra minutes. It is only a matter of time before the wrong tank gets overfilled. If it is an aluminum tank the results are usually serious for the wearer or filler. Ie: an aluminum tank at overfilled pressure tipping over onto a hard sharp edge, concrete curb, could cause a catastrophic failure in the vessel itself. That in itself could be the start of a bad day.

 

[ajtoady]

That being said, I will stick to my HP 117 Steelies and not be too worried about it.

 

[fire_diver]

an aluminum tank at overfilled pressure tipping over onto a hard sharp edge, concrete curb, could cause a catastrophic failure in the vessel itself. That in itself could be the start of a bad day.

They aren't balloons. A little common sense and rational thinking needs to be employed here.