THANK YOU SO MUCH FOR SAYING THAT. I have faber lp95's and lp120. from what I can find they are filled to 4k over seas. the only difference in the tank is the valve and it weighs 1-1.5 lbs more than the valve used in the us. It does not concern me at all filling to 3000 to 3300. i have 3k valves on mine. I wont store with that psi but i do fill to that for imediate use. BTW the tank weights in tank tables assume the heavy faber valve. That is why most have trouble with the bouyancy fweights listed.
LP vrs HP Tanks
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THANK YOU SO MUCH FOR SAYING THAT. I have faber lp95's and lp120. from what I can find they are filled to 4k over seas. the only difference in the tank is the valve and it weighs 1-1.5 lbs more than the valve used in the us. It does not concern me at all filling to 3000 to 3300. i have 3k valves on mine. I wont store with that psi but i do fill to that for imediate use. BTW the tank weights in tank tables assume the heavy faber valve. That is why most have trouble with the bouyancy fweights listed.
lamont
Contributor
The metallurgy is different. Don't fool yourself into thinking that 3500 or 4000 psi tanks are the same steel and its all just a difference of government regulations.
At the same time 2400 psi tanks are tested to failure by filling repeatedly to their bust disc pressure and must last for more than 10,000 cycles and must fail in leak before burst, and steel cracks very slowly. There also does not seem to be any cases of steel tanks exploding other than highly mistreated tanks (rusted out, massive overpressure without having a burst disc, etc). The practice of overfilling steel LP tanks to 3,500 psi does appear to be safe, but the HP tanks and the Europeans aren't using the same steel. You're participating in a large distributed metallurgy experiment every time you get a cave fill...
kanonfodr
Contributor
LP vs HP tanks...this debate again.
Speaking as someone who owns both (single HP120 and a set of PST HP100 doubles, single sets of LP85s and LP95s), they both have their pros and cons. LP tanks are bigger and heavier per capacity at rated pressure. I can handle my HP100 doubles with little drama, it's going to be a long time before I double up my LP95s.
The big thing, IMO, is how well the tanks trim out for you. A friend of mine who normally dives her HP100s in sidemount tried my LP85s and she really liked them, because they are long and thin, she can trim them out really well. For singles use I love my LP95s, they fit me so perfectly and the extra amount of gas I get really is nice.
Also, don't get more tank than you can handle on land. I hear about folks diving doubled LP104s and LP120s and cringe, my back would be screaming bloody murder. Also, depending on your regular diving and gas consumption rate, a smaller tank is perfectly acceptable. Many of my regular dive buddies dive LP72s and they come back with more pressure than I do, with an extra 20-30 cubes of gas
.
The basics of the argument come down to:
If you can get regular overfills (3000 psi +) in your LP tanks, go with LP tanks.
If you can't get good HP fills, get similar volume LP tanks.
There's a lot more to it, but before getting hung up on gas capacity vs tank weight or other figures, go out and dive as many different types of tanks as possible and see what works for you. Pay attention to your trim and how easy it is for you to hold trim while hovering. Then see how long the tank actually lasts you. Also, larger capacity LP tanks are generally much larger than their similarly sized HP counterparts. It can make a difference in your ability to swim the tank, and the extra resistance could negate the larger gas capacity the tank may offer.
But I re-iterate my earlier-stated point: trim is king, see what tanks make you feel the best and go get yourself a pair (or more).
Peace,
Greg
Speaking as someone who owns both (single HP120 and a set of PST HP100 doubles, single sets of LP85s and LP95s), they both have their pros and cons. LP tanks are bigger and heavier per capacity at rated pressure. I can handle my HP100 doubles with little drama, it's going to be a long time before I double up my LP95s.
The big thing, IMO, is how well the tanks trim out for you. A friend of mine who normally dives her HP100s in sidemount tried my LP85s and she really liked them, because they are long and thin, she can trim them out really well. For singles use I love my LP95s, they fit me so perfectly and the extra amount of gas I get really is nice.
Also, don't get more tank than you can handle on land. I hear about folks diving doubled LP104s and LP120s and cringe, my back would be screaming bloody murder. Also, depending on your regular diving and gas consumption rate, a smaller tank is perfectly acceptable. Many of my regular dive buddies dive LP72s and they come back with more pressure than I do, with an extra 20-30 cubes of gas
.The basics of the argument come down to:
If you can get regular overfills (3000 psi +) in your LP tanks, go with LP tanks.
If you can't get good HP fills, get similar volume LP tanks.
There's a lot more to it, but before getting hung up on gas capacity vs tank weight or other figures, go out and dive as many different types of tanks as possible and see what works for you. Pay attention to your trim and how easy it is for you to hold trim while hovering. Then see how long the tank actually lasts you. Also, larger capacity LP tanks are generally much larger than their similarly sized HP counterparts. It can make a difference in your ability to swim the tank, and the extra resistance could negate the larger gas capacity the tank may offer.
But I re-iterate my earlier-stated point: trim is king, see what tanks make you feel the best and go get yourself a pair (or more).
Peace,
Greg
GO to fabers website, look up the drawings and specs for a LP95 and a HP120.....Then try to convince me they are differant tanks, with different metals, or that we dont use the same metals that they use in europe(since Faber is made in Italy).
sillyness
The faber lp95 and hp117 look nearly identical, BUT they weigh considerably different. I own both and can immediately tell the difference by picking them up the 117 is nearly as heavy empty as the 95 is full.
on_two_wheels
Contributor
Lamont: Are you referring to the initial testing before production?
The hydro of most scuba tanks consists of filling the tank to the brim with water. Then pressurizing the tank to 5/3's it's rated pressure. A graduated cylinder measures the change in the water column as the tank is increased in pressure. After you drain the pressure in the tank the volume in the graduated cylinder must be within 10 percent of its original volume.
Basically what we are doing here is stretching the steel. Then measuring to see how close that steel comes back to it's original shape. If the change is more than 10% the tank fails.
Agreed! Double 95s are beasts (she says, having hauled them around for a week during Cave 2).
I'm with the OP, in general. If you have a shop that can give you good fills on HP tanks, they're nicer to live with.
lamont
Contributor
yeah, i'm talking about the initial testing before production, not a standard hydro.
the standard hydro does test how much the tank has cracked and how much the metal will flex under pressure, so if overfilling a steel tank does lead to more cracking it should be caught by the 5-year hydro.
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