is there a rule of thumb for air consumption?

[rexwang]

i was just wondering if there is a rule of thumb for air consumption that relates to a AL80.

i ask because on a AL80 i can dive for ~30-40 mins if im just cruising around, but if im hunting i get ~20-30mins. so im considering a steel hp120. it has better weight characteristics as well as more bottom time. but im wondering how much bottom time i can get.

thanks for the help.

 

[wrybosome]

There is a thread on how to calculate your air consumption here. Once you know the volume of air per time you're consuming, you can use that figure to calculate how long you'll get out of a different size tank.

SB user NWGratefulDiver wrote an excellent article about this which can found NWGratefulDiver.com. It's a great explanation of basic facts about Scuba air management.

 

[Teamcasa]

Welcome to ScubaBoard rexwang. The is no rule of thumb, just a method of measuring your SAC.

An HP120 will improve your bottom-time but only because it holds more air.

 

[XTX95]

No, there is no rule of thumb. Everyone breathes a little bit differently, hence why you should monitor your dive buddies' amount of air left as much as possible.

 

[dumpsterDiver]

Rule of Thumb: a 120 cu-ft tank will give you about 50% more time than an 80 cu-ft tank, all things being equal.

 

[a22shady]

As others stated calculate your sac rate and what your looking to get out of a dive and base it off that. Other thing to keep in mind when shopping for a tank is where you live. I have heard from others that have HP tanks that can not get a good fill. Me personally never had this happen here in NJ. Also the size of the Tank 120's are long tanks if your shorter person the tank may not fit right. also if you thinking bout doubles down the road calculate that into it. For me the best tanks were the Hp100 best overall weight/size characteristics for me and once IM ready to double them up will be easier to handle

 

[rexwang]

thanks for the welcoming, its nice to see a forum that still "welcomes" people.

my sac while cruising is ~28 and hunting is ~40

i know i know, i breathe alot. i cant help it, i love air. and i dont dive enough to be super duper calm, im always excited to be down there. the article looks really good but ill read it when im not at work.

im not overly concerned about the size of the 120 because its not crazy big, but i am concerned about getting more bottom time. my gf has a sac of ~30 while hunting, so im always the deciding factor of our dive times. i am always very aware of my air consumption and have passed on some huge fish with 600#s left at only 40ft. its just not worth it to me, i wanna keep diving not make it my last.

 

[Kern]

i was just wondering if there is a rule of thumb for air consumption that relates to a AL80.

i ask because on a AL80 i can dive for ~30-40 mins if im just cruising around, but if im hunting i get ~20-30mins. so im considering a steel hp120. it has better weight characteristics as well as more bottom time. but im wondering how much bottom time i can get.

thanks for the help.

This doesn't tell us much without a depth to relate it too. Big difference if you're getting these figures at 100' to 30'.

my sac while cruising is ~28 and hunting is ~40

.

What do the units represent; litres, cft, pressure per time?

 

[Kevrumbo]

My cold water SCR (Surface Consumption Rate) is 22 litres/min*ATA.

An AL80's single tank metric tank rating is 11 litres/bar.

22 divided-by 11 equals Two bar/min*ATA Surface Consumption Rate (SCR) in pressure units, for the AL80 single tank.

That's my rule of thumb applicable to me for my physiology and fitness level, using the Metric System --if it applies to y'all as well . . .sweet!

 

[rexwang]

This doesn't tell us much without a depth to relate it too. Big difference if you're getting these figures at 100' to 30'.



What do the units represent; litres, cft, pressure per time?

good point, the depths were the same thats why i didnt reference it. around 40' deep for both.

and my units for sac are psi/minute.