We look at why you should consider low pressure tanks vs high pressure tanks. The differences between these popular scuba tanks. www.divers-sup... Why choose one over the other and are there factors I need to know about.
Why not just use water volume of tanks and bar? Much simpler to deal with something like "I need a 15L tank filled to 230 bar" or "I'm using 2x12 twinsets filled to 300 bar"
Both means of measurement have their advantages. I'm used to working in litres/bar but knowing how much air you have in cubic feet is advantageous. It's very very easy to quickly work out how long your air will last. 1cu ft = 1 min (depending on your fitness). A 12L 232 bar = 100cu ft or 100mins at the surface, 50mins at 10m etc. It's a conservative figure but it's also very quick for a novice to grasp and plan dives. 10L 232 is 80cu ft, it's not an exact crossover conversion but it's pretty close. If you look you may notice that your cylinder isn't a 12L, it's a 12.4L and your 10L is 10.3L, these convert to cubic feet 😉
@@autoculto7629 It's easier to do these calculations with Bar and Liters than PSI and CuFt. With the Imperial measurement system you have to know the fill pressure of the tank to figure out how many CuFt of gas it actually has instead of looking at the tank's rated CuFt. With the metric system, you see that the tank (e.g. using a 15L) water volume and look at the SPG for how many bars of gas it contains. If you know your consumption rate (e.g. 15L/min for an average experienced diver), that's 1 bar/min at surface, 2 bar per min at 10m, 3 bar per min at 20m, etc. to figure out how long the tank could potentially last you if everything goes smoothly. If the tank is of a different water capacity, 10L tank or 12L tank or an 18L tank, and your consumption rate is 15L/min, it's a simple straight forward calculation. No need to do any roundabout calculations of trying to figure out how much gas the tank holds by looking at rated CuFt and then PSI and doing a complex calculation. Metric system: tank water capacity X pressure in bar in SPG = amount of gas inside tank in liters (all you need to know are 2 numbers) Imperial system is something like this I think: (filled pressure in PSI / rated pressure of tank in PSI) X size of tank expressed in CuFt = amount of gas inside tank in CuFt (you need to know 3 numbers and do both division and multiplication)
I'm well aware of the facts n figures and how easy it can be providing that you know your actual air consumption. 15L per min is very frugal, I'm around 22L per min now but I'm not as young and fit as I used to be lol. Getting a novice to understand and be able to do these calculations without even thinking about it ain't quite as easy. They have higher and irregular air consumption due to poor bouyancy control and breathing techniques. So if a cylinder is full you know that it's classed as an 80cu ft, one cubic foot per min consumption is 28L which is more than enough for a novice even when they don't know what their actual consumption is. If you need to work it out exactly then I totally agree that litres and bar is definitely the way to get it right, but for a very quick ball park conservative figure that leaves spare, 1cuft consumption per min is super quick for as novice to understand
@@autoculto7629 15l/min SAC is very generous. Normally I'm between 8 and 12. Also depends on the activity. If you're doing actual physical labour under water, it will rise quickly. Diving computers also show the current SAC and the remaining gas time at current depth.
A video to explain the difference on PSI vs air volume. I see some smaller tanks with the same PSI value as bigger tanks and don't understand how some small tanks would have more air than bigger tanks.
Think of it this way. A small car with 6 people in it have about the same space between them as a big bus with 80 people in it. 6cft tank and a 80 cft tank both at 3k psi... it takes longer to get those 80 people out of one door than 6. Hope this helps Regards Bob C
Pro valves are ideal for dive centers and if you've got yoke regulators and one day may switch to DIN. If you've got DIN regulators you might as well go for high pressure cylinders with 300bar DIN valves. You're not going to go back to yoke, and there is no benefit to buying pro valves for your cylinders.
Advantage; So an 85 LP Steel is full at 2400psi and an 80 Alum is full at 3Kpsi... does the compressor work harder to fill the Alum or Steel to give you aprox 80cft. If it's my compressor I'd want less wear and tear on it. If it's a shop compressor don't buy an 85... buy a 100 .. you're spending, within a few bucks, the same money. Enjoy the extra dive time without carrying a bigger dimensioned cyl.
@@DiversSupplyYT LP85 25.98" tall, 7" around, 31.2lb no valve. HP100 25.5" tall, 7.25" diameter and weigh 34lb. The LP85 will give 77cuft at 2400 which is what you're going to get on an LP tank after the first hydro unless you live in central fl. The HP100 will give you 87cuft @ 3000psi, when you get short filled which will be most south flordia dive shops, and 75cuft if you want to only fill it 2600psi. There really isn't any reason to buy a lp85 over an hp100 any more.
@@ChrisShaferKTM Can't disagree, the 100 steel is THE #1 tank we sell... my favorite, EXCEPT for folks that are vertically challenged, then the HP80 steel is my recommendation... That's for your comments
there is basically no advantage of buying a low pressure tank. a few real life considerations: - low pressure tanks can be filled with a low pressure compressor without adapter. (for a high pressure tank, you'll need one if you connect it to a 200bar line) - if you want aluminium (e.g. seawater consideration), you basically only get low pressure tanks. - with the 50bar reserve, a high pressure tank gives you significantly more airtime (250bar vs. 150bar - up to 66% more usable air) - if you're in a hurry, the high pressure tank won't be filled to capacity (mostly around 270 bar) I always buy high pressure (300 Bar). Most divers here in Switzerland buy low pressure tanks, for reasons I don't understand.
This completely misses the point. An under filled high pressure tank is a heavy tank with less gas. You could bring the same amount of gas with a much lighter LP tank filled to it's rated pressure. In general the weight/ft3 ratio is the same for both HP and LP filled to their rated pressure. The benefit of LP tanks is you never get an under fill. Not to mention over filling an LP tank is less dangerous than your drive to the dive shop.
Don’t really think major buoyancy difference can be defined in just 4 lbs from just the tank, most folks tend to dive over weighted without realizing they are doing it.
At 0:58 you define high pressure as greater than 3400 psi. Then you define low pressure tank as being between 2400 - 2600 psi. When you define these in terms of PSI, does that mean the amount of pressure that is in the tank, or does that mean the maximum pressure rating for the tank?
Hi B-Dogs, Thanks for your question. There are tanks that "most" divers call Low, Normal and/or High. Some divers call tanks "Bottles" vs tanks or cylinders. Certain terminologies have been used and/or abused over the years, just like the pressure rating of tanks of various tanks ratings. I speak to the 2400psi's I call Low pressure (actually that tank has a lot of pressure in it) . A 3k tank is the norm for the group of tanks mostly used in scuba diving today. The 3442 and above tanks I tend to address as High pressure. This is me based on my experience over the past 53 years of diving. Regards Bob C
Ya so ultimately for everyone watching, the answer is it doesn't really matter. HP tanks are harder to fill. Harder to find fill stations capable of filling a HP tank depending on where in the world you are. Some places who can fill it don't want to or they skimp you on a low fill. HP tanks hold more air. Do you need it? If not, just go with Low Pressure tanks they come in varying sizes also.
A low pressure tank that has the same capacity as a high pressure tank is a massive tank. My LP108s are heavy mothers that I hate dealing with, while my HP100s weighs about the same as an AL80. And even if a fill shops skimps you and gives you a 3,000psi cold fill you have the same amount of air as a LP85 with a + 10% fill. To be honest the only reason to own low pressure steel tanks is if you live in cave country and are able to get cave fills, otherwise just get high pressure steel tanks. I own LP steel tanks, and outside of cave country I can count on one hand the number of shops that will give me a proper cave fill on them. So I just make sure to top them off before I leave cave country.
Not trying to be a Wise-a__ but what some people say is NOT always correct... Since I've only been diving for 50 years and I work in the industry 50+hrs a week, I may not known much but I dive weekly with a Yoke 1st stage and a number of HP 3442+psi tanks... Now the Tech types will normally po-po Yokes and perfer DIN and rightly so because... If you're in an enviro where you can't make a direct ascent to the surface or you're outside your NDL to be able to make a direct ascent without risking DSC then the DIN's design of capturing it's O-ring does offer extra protection from that happening. ...BUT the simple statement that "Yokes are not "compatible" with a HP fill is not exactly correct. AND there are those divers out there, and you known who you are, that abuse a tank's pressure rating by OVER-FILLING and doing other such non-sense... I always say, "there's only one butt connected to the tank you're wearing", guess who's that is and who will suffer the consequences of SWD (studity while diving)... I could go on but I'll stop here....
@@DiversSupplyYT it really depends on what your definition of an HP tank is. When I hear HP I think of actual HP, which have the 4350 psi rated valves on them. That’s exclusively DIN territory.
@@DiversSupplyYT I call them standard. I just ordered a HP tank. Luxfer Limited 106. If it ends up working out as a single, I may make a twin set from them. Good point about the filling. I’m committed to the cause, though and I’ll just buy my own compressor if I have to.
@@RB-xv4si Ok standard ... is that the 3k, 3,3K or 4,3K that's standard.... Compressor, sure they are available today through Amazon at about $3,600 plus tax.. That's 220v so make sure you have accommodations in your home wiring for that and don't forget Filters and if you dive Nitrox get your O2 source ready. A 106 with it is only about 35 minutes after that.. Cool go for it !
Now adays when you can buy carbon fiber tanks that has a burst presure over 800 bar, is it possible to find a first stage that can handle around 500 bar or more?
Problem is Joel, really nobody is selling those tanks. Most shop compressors are not friendly, VIP/Hydros are yearly. Past 3 years they have not been shown at DEMA even...
Thanks VP, The biggest reason folks buy LP began because small compressors reach 2400psi easier than 3442psi. Lots less wear and tear on these compressors you see on small boats. There's numerous follow on reasons.
@@DiversSupplyYT Why not just fill your high pressure tank to lower pressures when you fill it yourself then if you need more air, let a shop fill it to high pressure as required. Seems like there is no actual benefit to a low pressure tank.
