Cylinder type and proper weighting (SPLIT FROM 'Pull Dumps - Lose them')

[rongoodman]

If your the right weight at the start of a dive you cant possibly be to heavy at the end of it, unless your refusing to let go of that porthole your carrying.

That assumes you finish the dive with your tank(s) empty. Otherwise, you still have the weight of the unused gas which must be compensated for in some way.

 

[Celt]

Some aluminum tanks are negative empty and some steel tanks are buoyant empty. I don't see *any* AL80 tanks in this table that are buoyant when full; in fact, I see only one in the entire table, the 14CF Luxfer:

http://www.indianvalleyscuba.com/services page/Tank Inspection/information/CYLINDER SPECIFICATIONS.pdf

Dry weight varies, too.

Do you have a reference that disagrees this this one?

Well ill put it this way, none of my steel tanks are buoyant empty, and all the aluminium tanks i have come across have been buoyant on the surface even when full, if manufacturers build extra weight into a cylinder, such as the new luxfer 80 obviously they are going to be heavier but there dry weight will also be heavier which the luxfer is, 35 pound, im talking about my experience with various diving tanks, if you wish to talk about your experience with different tanks then great but I've no intention of trawling through the internet for a load of useless information

 

[Celt]

That assumes you finish the dive with your tank(s) empty. Otherwise, you still have the weight of the unused gas which must be compensated for in some way.

no it doesn't, you cant finish a dive heavier than when you started. where is the extra weight coming from?

 

[TrimixToo]

no i meant full, the average aluminium 80 is buoyant when full, the new luxfer 80 is advertised as neutral but luxfer built 5 pounds weight into it giving it a dry weight of 35 pounds empty, when you check the specs from luxfer you get 4.1 pound positive empty and 1.4 pound negative when full don't know whats going on there. If you can sink a full 3mm wetsuit and an al80 with no lead you must be all muscle and bone and have a huge negative body bouyancy. what do you mean by if they are properly weighted?

Luxfer disagrees with you:

L6X® aluminium SCUBA cylinders

(Edit) So does Catalina:

https://www.catalinacylinders.com/wp-content/uploads/2017/03/SCUBA-.-SCBA-.-Spec.2-11-15color.pdf

 

[Celt]

You mean if you place an AL80 tank full with 3000 psig air in a pool, it will still float?

the new luxfer won't but the average al80 will, salt water.

 

[Celt]

Luxfer disagrees with you:

L6X® aluminium SCUBA cylinders

Like i said in other posts if a manufacturer builds extra weight into a cylinder obviously it will be heavier, but the dry weight will also be heavier 35 pound empty in the case of the luxfer.

 

[oldschoolto]

Gas has weight.. if you have full tanks when you start your dive you MUST be negative to end the dive being able to hold a deco stop..

Jim....

 

[TrimixToo]

Like i said in other posts if a manufacturer builds extra weight into a cylinder obviously it will be heavier, but the dry weight will also be heavier 35 pound empty in the case of the luxfer.

One of us is confused. You asserted (twice) that full AL80s float. I do not agree. I cited references. Find me a manufacturer's spec that says an AL80 floats when full. Luxfer, Catalina, and Metal Impact all say theirs do not float when full. I have never seen an AL80 that floated when full, I've owned them from the two largest manufacturers, and when I started diving aluminum cylinders were pretty new on the market. Even my old AL72, which is terribly floaty when empty, is still negative when full.

What am I missing (scratching head)? (Edit) Am I missing that it's 1 April? Hmmm.....

 

[divad]

My neighbors dogs are barking and are barking too loud and too much....what should I do?

 

[Steelyeyes]

AP Diving still makes BCDs (Buddy and Commando) to which you can connect a small air bottle topped up from a tank. The bottles valve design looks like either a yoke or DIN regulator connector so it matches perfectly to be topped up from the tank. They have been making these for decades.

A much greener solution than disposable CO2 cartridges.

The idea behind the CO2 cartridge is for emergencies only. They're light, they are simple and require minimal other gear, they work, and a little bit of CO2 you may release once in your life won't be more the the stuff you'll breathe out from the time you survive the issue until you die of something else, hopefully far later in life.