Air Hog

[ages]

Never NEVer NEVER (I can do this because I am an old lady and a Mommy) hold your breath while diving. You do not want to experience trauma to your lungs. And none of us want to pull your sorry carcuss out of the water!! Rescue skills are not a pleasure to practice!!

I had an old divemaster tell me to concentrate on my breathing. To calmly breathe in for 10 seconds then breathe out for 10 seconds. When you can do this, you will only breathe 3 times a minute. I haven't made it to the full 10 seconds yet...but I can easily do six or seven. That has helped me the most. I started practicing in the pool. Putting my gear on and just swimming in the dive shops pool and practice breathing (didn't make it to 10 seconds in the pool either)!!

Then, I recommend purchasing some HP tanks. You can get HP 80's or 100's or 120's. The 120's are really big. I think you'll find 100's would be perfect.

Just my long winded $.25!! ages

 

[Warhammer]

Get the whole family involved. The best part is it will also help you to avoid Aquatic Induced Divorce Syndrome.

 

[DiverInAk]

Everyone has nailed this well, and I have but one more thing to add. Just relax and enjoy the dive. I think if you get too caught up on how much air you're using, you tend to raise your consumption even more.

Use the time out of the water to increase your lung capacity and aerobic activity. Concentrate on relaxation, and may I suggest YOGA? Yoga, besides the stretching portion of it, is all about breathing. You MUST breath DEEPLY in order to get the benifit of the various positions.

The calmer you are in the water, the easier it will be for you to control that breathing.

Oh, congratulations on getting a diving family together. I am looking forward to getting my two kids certified in April. After that, a family that dives together, ........... Well it just makes for more expensive vacations now that I think about it.

Just kidding.

 

[turnerjd]

Originally posted by Iguana Don

2) if bigger is not possible, go for a higher pressure - I use 300 Bar (4500 PSI) rather than the 232 Bar (3000 PSI) standard tank.

Jon, If I am reading this correct you are suggesting he get a HP tank over a LP tank.

The pressure rating of a tank has no bearing of the volume of air it holds.

80cu ft is 80cu ft whether it is in a LP or HP tank.

This is a common mistake made by lots of people including myself until I saw the light.

ID

ID,

Unfortunately, this is where Europe and the US are different. We measure tanks by their internal water volume (ie how many litres of water to fill a tank). Tanks are usually 10, 12, or 15 L internal volume.

Then, as well as by internal volume, we sell then by different working pressure, either 232 Bar, or 300Bar.

So, you can go and buy two tanks of the same internal size (eg 12 L internal water volume), but of different working pressure. Now, using the ideal gas law

P1 V1 = P2 V2

Take the low P tank, fill it up, then expand that air to 1 atmosphere, we have

232 x 12 = 1 x V2

V2 = 2784 L

(ie 2782 L of air from the atmosphere have been squashed into our 12L tank)

Now repeat for the HP tank

300 x 12 = 1 x V2

V2 = 3600 L.

In the US you sell tanks by the ammount of atmospheric air in them, which would be the same number as V2 above, just converted to cuft.

What I was suggesting, and sorry for any confusion by my using european measurements, was that he buys a tank of the same physical size, but at a higher working pressure as in the example above.

The only problem with the ideal gas law as used above, is that air isn't an ideal gas, and unfortunately in the 300 Bar tank you dont get 3600/2786 times as much air in the HP tank as in the LP tank.

HTH

Jon T

 

[Iguana Don]

Jon,
Several months back, I asked Rainreg, the difference in HP/LP tanks and he said there is a measurable difference in
the amount of useable air in a H/P tank. Is this what he had refrence to?

ID

 

[turnerjd]

Iguana,

Yes, I would assume he meant for any particular fixed internal size (water volume) a higher pressure tank has more air 'squashed it'.

Jon T

 

[Rick Murchison]

IG asks about the "measurable difference" in usable air.
The usable air in a tank is all the air that can be evacuated from the tank due to the pressure in the tank - in other words, all but the air left in the tank when the tank reaches ambient pressure.
Lets compare theoretical 100 CF tanks, a very low pressure and a very high pressure - tank "A" is full at 2000 psi and tank "B" is full at 4000 psi. The interior volume of tank "A" will be 100/(2000/14.7) while the interior volume of tank "B" will be 100/(4000/14.7) - or .74 CF for tank "A" and .37 CF for tank "B", and the usable air at the surface for tank "A" is 100-.74 = 99.26 CF while for tank "B" it's 100 - .37 = 99.63 CF, a "measurable difference" of .37 CF. At a depth of 100' that "mesurable difference" becomes 1.48CF. In either case, that's nearly a full minute of breathable air for most folks, so it is "measurable."
------------------
But..... now, let's look at the other side of the coin. If you were to breathe both tanks dry at 100' (and you'd exhaust tank "A" a minute before tank "B"), you'd have 4 X .74 = 2.96 CF trapped in tank "A" and only 1.48 CF trapped in tank "B". In an emergency ascent to the surface tank "A" could be expected to free up 3 X .74 = 2.22 CF of breathable air, while tank "B" would only free up 1.11 CF.
So, would you rather have the low pressure tank that runs out sooner, or the high pressure tank that frees up less on an emergency ascent?
Personally, I'd rather watch my air, in which case the "measurable differences" become irrelevant.
Rick

 

[Marine801]

Sounds like everyone's got you covered with gear other equipment suggestions. It is so true that there is no substitute for experience. I'll make one suggestion though that might help. When you breath through your reg do you close off your nasal passage? I mean are you using your soft palate to isolate your nasal airway because you're breathing through your mouth? If you are try relaxing your soft palate and opening your nasal passage. Don't worry its not like your mask is gonna fly off or your gonna suck that water that's always in the nasal part of your mask skirt in through your nose. When you deliberately breath through your mouth and block your nasal airway your breathing is going to be very different than if your airway is relaxed. You've interrupted a reflexive activity and are now trying to consciously control it. Its never as efficient as if you let your body manage everything on its own. Give it a try. Your breathing rate should slow and you'll generally feel more relaxed. Good luck.

 

[turnerjd]

Rick,

Aah, that explains it.

Obviously, as we measure and sell tanks by internal water volume, this question does not arise as there is the same amount of air left in an empty european tank irrespective of operating pressure, because they have the same internal volume.

As for which I prefer, by the european definition, I prefer a HP tank of the same internal (water) volume, as it has 30+% more air in total.

(P1 V1 = P2 V2 again, a LP 12L = 2760 L air, HP 12L = 3600L air, however, this is like comparing a US LP80 with a HP120, which I think will both have approximately the same internal water volume)

Jon T

 

[kyleterry]

Hey Guys,

Thanks for the info you gave Kyle. He has been practicing in the bathtub. It works great!

His Wife