Help, 100 cf Aluminum tank???

[outlawaggie]

I'm an air hog. On standard AL80's I am always first out of air. I was looking at a 100cf Aluminum tank. How much "more" air does this equate to? Do 100's present any issues over 80's.

Does anyone else have a better solution? I am working on my air consumption but that does help right now.

 

[scubatoad]

Assuming that you use all the air in your tanks (although we never do) you would have 25% more air/time with the 100cf tank. The useable air ratio should remain about the same.

Similar thinking would give you 50% more air with a 120 tank (over an 80cf tank)

 

[TwoTanks]

A 100 CF tank has 25% more air than an 80. If you were getting 40 minutes of bottom time with an 80 you will get 50 min. with a 100 CF tank. Im not familiar with 100 CF aluminiums but if it is high pressure than you may need to have a din valve. You should be aware of the valve type and keep in mind that your weighting will be a little different.
The best way to improve your air consumption is to dive, dive and dive. Your air consumption will go down as your experience increases.
As you breathing does improve, the added bottom time from the 100 CF will allow you to get into a deco dive if you aren't careful, so be sure to watch out for that.

Enjoy

 

[outlawaggie]

Assuming that you use all the air in your tanks (although we never do) you would have 25% more air/time with the 100cf tank. The useable air ratio should remain about the same.

Similar thinking would give you 50% more air with a 120 tank (over an 80cf tank)

They don't make a 120 Aluminum do they??

 

[ShakaZulu]

Look at steel, not sure how much, but I imagine you'll have much more positive bouyency with a AL120. Really gonne messup your weighing.

 

[outlawaggie]

Look at steel, not sure how much, but I imagine you'll have much more positive bouyency with a AL120. Really gonne messup your weighing.

OK but can yoiu explain the whole Low Pressure/High Pressure thing to me. I have always used regular AL80 at 3000psi. My understanding is that a Low pressure tank has the same "amount"of air but at a lower pressure so the tank is a little bigger. Is that right? Or is it less air?

 

[Otter]

The AL100s are BIG so if you aren't prepared to haul around that much size/weight, go steel. As ShakaZulu said, the buoyancy characteristics are much more favorable. When I switched to an steel HP100 (PST E-Series) from an AL-80, I dropped 5 lbs of lead. The E-Series also have the advantage of working with either a Yoke or DIN regulator so you won't have to change your 1st stage.

Personally, I'd advise against the 120 at this point. Assuming you're a new diver, you should see a significant improvement in air consumption the more you dive. Now if you tell me you are 6-8 and 300lbs, I might change my recommendation.

Good luck.

 

[redacted]

I'd estimate you should get about 1/3 more bottom time. Assuming you keep 500 psi in reserve on that Al80, that amounts to about 13 cu ft. That Al80 is really about 77 cu ft so you would be using 64 cu ft on a dive. If an Al 100 is really 100 cu ft and you keep the same 13 cu ft in reserve, that give you 87 cu ft to use. And 87 is 38% more than 64 so 1/3 longer dive seems about right for a planning factor.

 

[matt_unique]

OK but can yoiu explain the whole Low Pressure/High Pressure thing to me. I have always used regular AL80 at 3000psi. My understanding is that a Low pressure tank has the same "amount"of air but at a lower pressure so the tank is a little bigger. Is that right? Or is it less air?

The pressure difference is the pressure required to fill the tank to its rated capacity. A LP 100CF tank has the same amount of air as a HP 100CF tank The AL's have some nutty buoyancy characteristics. When full an AL 80 is approx. 4 pounds negative and goes to 2 pounds positive when empty (or vice versa - brain cramp - but the change in buoyancy is 6 pounds from full to empty). An alum 120 would be a big tank. I have only seen AL 100's personally and those are tall.

--Matt

 

[mech]

You are going to see some improvement as you do more dives.
I believe that steel tanks actually help you conserve air due to requiring less weight on you belt.The thing with them large aluminum tanks (and I don't know if they even make them that big) is that they are going to be vary bouyant at the end of the dive and will need more lead to counter that.
This conserving air thing probably has at least a dozen variables to it like cardio health, breathing pattern,being comfy with your gear and so on.
each time you successfully apply/complete one of the variables it adds up.