Let's Talk About Cylinders | Deep Dive 

Chapters [1:23] Size [5:37] Pressure [7:16] Material [8:27] Markings [10:32] Valves [15:14] Bottom [15:57] Colours [17:16] Finish [19:26] Testing [22:08] Care [25:14] Twins [27:25] Buying Tanks [30:15] Stickers [33:03] Fill [36:52] Travel [42:03] Inverted

Common US tank sizes and common purposes for them. Aluminum: Anything below 20 cuft: Shallow bailout/pony, argon, rebreather bottles 30: Mostly bailout/pony 40: Deco bottles, and bailout for anyone that realistically calculates their SAC/RMV 63: Smaller primary tank, mostly for women and children 80: The gold standard, what you will get if you rent a tank. Also used a stage bottles for tech divers, and as BM doubles for warm water. 100: Uncommon, but are still available often when an operator says that they have larger tanks it is one of these. Steel: High Pressure (3,442psi/232bar) 15 and 23: CCR tanks, often labeled by their metric water capacity, 2L and 3L respectively. 80: Smaller tank used by smaller people, about the size of an AL63. These are often only personally owned. 100: Pretty much the standard steel tank, about the same size as an AL80. When an operator says they have steel tanks it will probably be these. As very commonly used a backmounted doubles. Everything else: Less common, but still available Low Pressure (2,640psi/180bar) Low pressure steels are pretty uncommon, most people buy HP steels due to capacity vs size/weight. The are most commonly seen in Northwest Florida, Cave Country, where they are given cave fills to around 4,000psi. These are sold mostly as painted tanks, as the galvanized tanks are heavier. 27: CCR tank, sold as a 4L tank. 50: Becoming more common, great smaller tanks for shorter dives used both sidemount and BM doubles. A buddy used them as bailouts for his CCR. 85: Pretty much the standard sidemount tank, sometimes used as doubles for smaller divers. 95: Sometimes used as sidemount tanks, but isn't that common anymore. In the past they were popular BM tanks. 108: Pretty much the standard backmounted doubles tanks. And if anyone is wondering how to do dissimilar gas matching (ie making sure that we have enough reserves for everyone) we use "tank factors" to quickly convert from pressure to capacity. It works pretty much similar to metric. So I know that my LP85s will have 6.4cuft for every 100psi of pressure. So if I have a 3,600psi fill, I have a 1,200 third. So I have a 76cuft third, I hand that to my buddy running 108s. He takes that and divides that by his tank factor (which for all LP10Xs we use 8), so he only has 900 psi to work with to ensure that he never uses more than my reserve third. So his turn pressure if he starts with 3,600psi is 2,700psi.

Here in the US we like to make tanks sizes as confusing as possible.

Thanks Mark, this a brilliant comprehensive explanation. I have been searching for such an explanation in my research prior to buying tanks. In the end I went with 15 litre steel 230 Bar tank for exactly the reasons you mentioned. Great to have that confirmation. Thanks as always great to see you back in the blue shirt!

Great deep dive! So much information that went way beyond what I was expecting. If you're a new diver don't worry about getting overwhelmed. Mark did a great job at breaking down the most important tank features in the order presented in the video.

Just getting back into diving after a long break. You’re videos are amazing, my go to for current info, and really useful for in-scene opinion. Fully subscribed!!!

Very informative, filled in some very useful knowledge gaps I didn't know I had. Thank you!

Thank you man I'm going to start suba diving next year so this helps alot.

Another newbie getting an awesome heads up! Thank you and carry on please.

Great comprehensive video! Thank you!

Thanks enjoy watching your vids relatively it helped a lot new to diving and slowly purchasing my gear. I’m looking at the faber 18l 232bar (x2 for double boat dives) as my next purchase I tend to use up my air quickly on the 12l tank and with a 5 hour drive to the coast each time would prefer to make the dive last as long as possible.

Great thanks for the info it’s been awhile since thinking about this stuff so a few pennies have dropped in my head again cheers

Thanks for the info, exactly what I needed!

Man amazing video even though I am not done with it. No WAY you did this in one sitting. Amazing job

Woah didnt realize you guys were back, haven't been getting notifications.

Watched it all! Very informative. Thank you :-)

Just excellent. Well done and thank you.

As Always, Good Info 👍🏼 I just purchased a HP Steel 149CF (19L) Cylinder It's big, but I'm a bigger guy (6'-3" 250lbs / 189cm 113kg) I've suited up in it and the weight isn't an issue for me. I'll test it in the water this weekend. The Buoyancy Swing is a bit high -9 / +2, but I'll see how to compensate for that. I think the Cylinder fits my Physique the way an 80CF fits an average size person. I tried to find videos of people using a 149CF (19L) Cylinder but I couldn't find any.

The situation with plugs you mentioned is called dissimilar metal corrosion. If you want to use a metal plug make sure its as close to type of metal the valve is made out of. If your unsure of what metals will have the least effect google the galvanic scale. The closer they are on there the safer you are.

galvanic corrosion is what fuses dissimilar metals, like brass and and steel, say for instance in a 20 year old chevy brake line.

NEVER have an alloy cylinder powder coated. It's a lovely hard wearing finish that looks good for a long time BUT the powder coat oven is set above the alloy's tempering temperature and the alloy becomes very weak. Someone tried this at my Uni dive club at great expense.

Very informative. Thanks much!

Reading through the comments it shows to me how training has changed. Back in 1984 one of the sections in the BSAC novice diver qualifications was the " Equipment lecture " which you had to get signed off and most of the time in that lecture was spent on tanks, types, inspections, markings, safe handling and everything else you covered. It surprises me that very obviously qualified divers in the comments show they have holes in their knowledge base, so in this respect you must be congratulated on a job well done :) .Sign of the times I guess but then I only moved up from an ABLJ to a BCD two years ago even though I have been advanced since 94 , loved my buddy arctic and twin 10's

Currently using Faber 15ltr steel cylinders as I’m still a gas guzzler and go through air as if my life depended on it. And how did Sean let you get away without the “tanks for watching”?

For florida in the US, visuals expire after 1 year, hydros are 5 years, the visual is marked by a sticker with dates and o2 clean status, hydros are stamped in the shoulder of the cylinder with a month special stamp in the middle of where it was hydro tested and then year Like: 5 ☆ 17

Excellent training.

Heya mark, a couple pictures would be useful for some of the topics. Cylinder markings in particular

I do have 12L 300bar and 10L 300bar steel tanks, i just top them off just before diving (got my own compressor) so they will be closer to the 300bar, i did buy 300bar cilinders because my gas consumption whas more than other divers but after taking more dives my consumption went down and i mostly still have a bunch of spair air in there now.

Bouyoncy gathered from used air (and a need to compensate by lead) is exactly the same for steel and aluminum tanks (if only volume of used air is the same).

Great episode Mark! I am in the US, and a bit of a gas hog- so I am currently diving with single steel 100, looking to go to doubles next year once i finish my AOW certification!

FYI. From USA. Went scuba diving in the Bahamas in 2014, (Intro to scuba, kinda thing, Stuart Coves ((Absolute Recommend)) LOVED IT!!!!!!!! I Didn't Equalize correctly on way down, when back on the boat, hocked a blood loogy the size of a baseball and had HORRIBLE headache for a day.... Still, LOVED IT!!!!!! I have some locals that train... $$$$ and Time is the issue. Thanks for this video and ALLLLLL of the other videos. I've got 5 hobbies.... and not enough money or time......

Very informative, thanks a lot! It would be nice though to visualise the information a bit more for beginners to understand it better

Havnt actually been on a dive for nearly 30 yrs. used to have alloy 88cf tanks and had a couple of 72 steel . In Australia

Interesting vid, thanks. Could have done with a few pictures to help with what you were talking about too.

everything you didnt know you needed to know about tanks.

Hi Mark, great video thank you. I currently deciding whether to buy steel or aluminium cylinders for deco. I currently dive twin 12 fabar, i know you touched breifing on there differences, however i wanted to know how much buoyant do aluminium cylinders get ie is it enough to create a rapid ascent? I will be using the deco cylinders for nitrox 50% any advice you may have would be greatly appreciated.

Hey Mark, thanks for the video. Why did you say that aluminum cylinders are better for stages/ sidemount? For me it’s quite annoying bringing more weight to compensate their buoyancy variation. I understand that in warm salty water they use aluminum cylinders to avoid corrosion, but in the rest of the cases it doesn’t make a lot of sense to me. Could you please elaborate more on this topic the next Q&A? Thanks a lot!

I have dumpy 12s. They're my favourite thing ever!

I am pretty sure that M25 is pretty much isolated to Europe, and countries where most of the tourists come from Europe (like the Red Sea). the 3/4" NPS is the most common tank threads I've seen around the world. There is an increasingly uncommon 7/8" UNF threading that was for true HP steel tanks (3,500psi or higher) in the US to ensure that you never put a lower pressure valve on it. Those valves were non-convertible to yoke and were 300bar DIN only. But with the adoption of the 3,442psi HP steel tank, those tanks are no longer made and they are becoming increasingly uncommon.

What is TOO FAST tank filling. How long should it take to fill a 15 l tank that is half full already. (WP 232)?

Thanks but it would really help to show us the tanks as you talk about them.

Great video. I'm just about to buy my second tank and your advice gonna help me a lot. Me and my regular buddy currently use 15l/300bar tanks, but it isn't the best solution for two reasons: 1) diving centers where we usually dive (in Croatia, Europe) can only fill up to 232bar, so we can't use the full potential of our tanks. 2) I always use somewhat more air than my buddy, so we usually end the dive with about 30bar difference. My solution would be to sell my 15l/300bar and buy 18l/232bar. Later, my buddy may sell his 15l/300bar and buy 15l/232bar. One important topic may be added to your great video - the tank weight. We need to carry these things around a lot before even entering water. By doing my own research, I discovered that 18l/232bar (steel) has almost the same weight as 15l/300bar (steel) - when you get Archimedes principle into account, 18l/232bar(steel) is even slightly more buoyant than 15l/300bar (steel), especially when on low pressure?

Tank: noun. A receptacle, container, or structure for holding a liquid *or gas.*

Have a 149 and 133 HP, not small, but we are diving deep in the states

I'm a beer tank. Lol 😆

Lmfao RU-vid seems to know I just bought a new tank too ! Lmao I got a purple anodized aluminum 80 for 120 bucks!

Important thing: 10l 300bar is NOT the same as 15l 200bar. About the colour: DON'T paint the tank red (reserved for fire extinguishers) or "deep blue" (reserved for propane).

The old American standard was 71 cu ft.

Does your shop not sell cylinders?

I thought tanks are used to invade poland

🤗

Just one correction: Steel cylinders are actually lighter than comparable aluminium tanks. Yes, in the water they are less buoyant due to thinner walls.

Ok, you start by telling us the different between tanks and cylinders and proceed calling them tanks ? Really.