15l tanks

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They are Catalina 100 aluminum.
 
As a standard Meridiano 87 fills ALL aluminum tanks to 3000 PS. If you got 3145 that was an accident, but even then it is not 100cf. There is a good reason that Aldora pays 3 times as much for Steel HP 120 tanks, with lots more for maintenance--and has their own fill station.

In addition, THE Steel HP 120s have ideal buoyancy characteristics compared to any other tank.


Bear in mind that there is a huge difference between high pressure steel 120s and Low pressure 120s.

Dig into the above charts and others,and you will see that when full the hp 120s have more weight to get down easy, then never positive at the safety stop. For example, depending on brand the aluminum 100 may be as much as +7.8 pounds buoyant. When diving HP 120s most divers take 4 lbs off the weight belt when compared to Aluminum 80s. Aluminum 100s better add 4 lbs.

One more thing, the bulk of the Aluminum 100 or low pressure steel 120s is difficult to dive with. In fact it is my belief that dealing with the bulk of them may cause more divers to use up any extra air to be found in the tank.


Dave Dillehay

Not my money but I could debate this forever.

I especally agree with "the bulk of the Aluminum 100 or low pressure steel 120s is difficult to dive with. In fact it is my belief that dealing with the bulk of them may cause more divers to use up any extra air to be found in the tank." Those things are huge 'missile silos' both above and below the water and often result in 'one step forward, two steps back' with respect to manageability.
 
I especally agree with "the bulk of the Aluminum 100 or low pressure steel 120s is difficult to dive with. In fact it is my belief that dealing with the bulk of them may cause more divers to use up any extra air to be found in the tank." Those things are huge 'missile silos' both above and below the water and often result in 'one step forward, two steps back' with respect to manageability.
I think if you happen to get the standard 3000# fill on the LP120 you will have enough air to overcome any additional bulk.
 
As a standard Meridiano 87 fills ALL aluminum tanks to 3000 PS. If you got 3145 that was an accident, but even then it is not 100cf.

For example, depending on brand the aluminum 100 may be as much as +7.8 pounds buoyant. When diving HP 120s most divers take 4 lbs off the weight belt when compared to Aluminum 80s. Aluminum 100s better add 4 lbs.

One more thing, the bulk of the Aluminum 100 or low pressure steel 120s is difficult to dive with. In fact it is my belief that dealing with the bulk of them may cause more divers to use up any extra air to be found in the tank.


Dave Dillehay

Not my money but I could debate this forever.

Hi Dave,
Per my dive logs, all fills for the 10 dives using the 100AL's were over 3100 psi. It should be noted that it is not uncommon for me to get 80AL tanks that are 2700 - 2950 psi. I will reject any tank below 2900. I honestly didn't notice any buoyancy issues during any part of my dives. Good buoyancy has never been an issue for me though, regardless of what gear I am using. I am a bit of a gas hog and I have to focus on good breathing techniques when using 80's. With the 100's I did get longer bottom times and even though I still focused on good breathing techniques, I was always last to surface with the DM. I have wanted to try the steel 120's and perhaps I will on my next Coz trip this April.
 
Hi Dave,
Per my dive logs, all fills for the 10 dives using the 100AL's were over 3100 psi. It should be noted that it is not uncommon for me to get 80AL tanks that are 2700 - 2950 psi. I will reject any tank below 2900. I honestly didn't notice any buoyancy issues during any part of my dives. Good buoyancy has never been an issue for me though, regardless of what gear I am using. I am a bit of a gas hog and I have to focus on good breathing techniques when using 80's. With the 100's I did get longer bottom times and even though I still focused on good breathing techniques, I was always last to surface with the DM. I have wanted to try the steel 120's and perhaps I will on my next Coz trip this April.

Im glad to hear that some of your Aluminum 100s were up to 3100 PSI. Perhaps Meridiano 87 has gotten some message but at 3100 you are still not near 100cf. As for the HP 120s you can get while diving with Aldora which has its own fill station which happened after repeated short fills. Liquid Blue also has HP120s but I don't know how they fill their tanks.

Dave Dillehay

Again NO financial interest in Aldora Divers
 
What is the max psi for an aluminum 100/15L? I'm paying $15 a tank for this privilege, and I better get decent fills.
 
What is the max psi for an aluminum 100/15L? I'm paying $15 a tank for this privilege, and I better get decent fills.
Generally (I think probably always) the service pressure is 3300 PSI.

So you understand why it may not be as simple as one might think to get that fill:

Tanks at all but the smallest operations are probably not filled one at a time, with someone monitoring the PSI. There are banks of multiple fill whips attached to rows of tanks, and a regulator in the line that is set to stop the fill at a certain pressure, probably 3000. With the regulators that I am familiar with, even temporarily adjusting that regulator up to a higher (or lower) pressure is not as simple as turning the dial to a preset position. It takes a little more effort to zero in on the desired set, and then the same effort to return it where it was.

Now, even if you have a fill station that makes that effort, or does enough 3300 fills to have a separate line with a regulator set for that pressure, you will also have an issue with the PSI falling a bit as the warm/hot tank fill cools down. Again, is the operation taking the time to go back and top off, or just leaving it at a "close enough" value? While I am sure many operations overfill in anticipation of the tanking cooling down to about where it should be, topping it off is the "by the book" method and no one should be faulted for following it.
 
What is the max psi for an aluminum 100/15L? I'm paying $15 a tank for this privilege, and I better get decent fills.

Well, perhaps my math is fuzzy, but I think you should consider going the Aldora route. If you're shelling out $30 extra per trip for AL 100s (meaning you'll get anywhere from 90-100 cu ft) vs 120 cu ft. If I understand correctly, the 120ies are included in Aldora's price. One would have to get a heck of a deal to make up the difference. Even then, you're short 20 cu ft.

I too find steel tanks more comfortable in the water than Al. In fact, I would take a good old 72 (71.2 cu ft @ 2475 psi) over an Al 80 any day-I know to others it does not seem to matter.
 
Yea, but nitrox is included so it's a wash.
 
Yea, but nitrox is included so it's a wash.
Again my math might be a bit fuzzy, but if IRCC Aldora only charges about $10 for nitrox so your Al 100 for $30 vs steel 120ies for $20 doesn't seem a wash to me. Not to mention, if your "100s" are filled to:
psi-----cu ft
3000 = 90
3100 = 93
3300 = 100
 
https://www.shearwater.com/products/swift/

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