Questions on air at depth........

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Hi, may some experienced divers here, help with some questions?

1. As we decend to depth of 10 metres, so at 2 ATM. The compressed-air is one-half,
so "WHAT" is the other one-half in the scuba tank?

2. At a depth of 40 metres, and the remaining air in the tank is 50 Bar. Is the air enough for a safe ascend to the surface, and how many deco-stops or safety-stops are needed, at what depth and the duration needed at every stops? :06:

Thanks.
kit.
 
1: no you still have exactly the same volume in the tank. The air inside the tank is already compressed. The only way it could compress more would be if the tank itself were to start to compress. Once the air comes out of your regulator, then it is compressed to half its surface volume.

2: That's all predicated upon the profile of your dive. What is the psi equivalent of 50 bar? If you haven't exceeded no decompression limits on your dive, then a deco stop is not warranted. Safety stops at 15'/5m are generally recommended for shallower/shorter dives and strongly recommended when dives are deeper and closer to NDL limits.

the K
 
kityip:
Hi, may some experienced divers here, help with some questions?

1. As we decend to depth of 10 metres, so at 2 ATM. The compressed-air is one-half,
so "WHAT" is the other one-half in the scuba tank?

2. At a depth of 40 metres, and the remaining air in the tank is 50 Bar. Is the air enough for a safe ascend to the surface, and how many deco-stops or safety-stops are needed, at what depth and the duration needed at every stops? :06:

Thanks.
kit.


You're missing a detail. The internal volume of a *fixed* (or rigid) container (one that does not compress, like a scuba tank) will not be affected by external ambient pressure (unless that pressure is enough to crush it). A *flexible* container like a balloon, your lungs or your BCD is affected by external ambient pressure.

Make any sense?

R..
 
The tables I have has 42m. You can stay at that depth for 6min withouth a need for stop. if you stay for 10 min then you have to make a 1 min stop at 3m. if 15min 1 min at 6 and 4 min at 3m....
 
kityip:
Hi, may some experienced divers here, help with some questions?

1. As we decend to depth of 10 metres, so at 2 ATM. The compressed-air is one-half,
so "WHAT" is the other one-half in the scuba tank?

2. At a depth of 40 metres, and the remaining air in the tank is 50 Bar. Is the air enough for a safe ascend to the surface, and how many deco-stops or safety-stops are needed, at what depth and the duration needed at every stops? :06:

Thanks.
kit.

Well, look at the bright side. If your gauge will read 1/2 tank of air left at 2 ATM, when you ascend back to the surface it will be full.
 
This must be what they are talking about when they mention "ideal gases".

LOL!
 
kityip:
2. At a depth of 40 metres, and the remaining air in the tank is 50 Bar. Is the air enough for a safe ascend to the surface, and how many deco-stops or safety-stops are needed, at what depth and the duration needed at every stops? :06:

Thanks.
kit.

Need more info - what about the rest of the dive profile (depth/time)? And what kind of tanks being used? How quickly do the divers suck down gas?

50 bar is about 735 PSI. I don't think it's a good idea to plan on breathing a tank down to that at 130 feet. You'd probably exceed the NDL, and... I'm not trained for deco diving, so I won't even try to give advice on the deco stops.

For safe dive planning, lots of people suggest the rule of thirds: 1/3 of the tank to get down and look around, 1/3 of the tank for reversing course & ascent, 1/3 of the tank for emergencies. Now, I don't always follow that, but then most of my dives are in less than 60 ft (18m) of water. For a dive to 100+ ft, I would definitely use the rule of thirds in planning. Even assuming you're using a LP steel tank, 750 PSI is less than 1/3 of the full tank pressure, so you've used waaaaay too much gas to still be sitting at 130 feet.

I personally wouldn't do a dive to more than 110 ft - beyond my skill level. The fact that you have to ask about the necessary decompression for the dive (without other information like the rest of the dive profile, and the breathing rate of the divers involved) leads me to think that you should not be planning a dive to 130ft (40m).
 
kityip:
1. As we decend to depth of 10 metres, so at 2 ATM. The compressed-air is one-half,
so "WHAT" is the other one-half in the scuba tank?
It's kinda like this:

If you pack in a bunch of foam rubber into a tank until it's full, then stuff the same amount again into the tank, as you later remove the foam rubber, the remaining foam expands, keeping the tank full of foam rubber even when it's half filled.

So for now on, if you complain to you're LDS that you didn't get a full fill, he can say, "Yes you did. What else is the tank full of?"
 
kityip:
Hi, may some experienced divers here, help with some questions?

1. As we decend to depth of 10 metres, so at 2 ATM. The compressed-air is one-half,
so "WHAT" is the other one-half in the scuba tank?

Thanks.
kit.

No Kit, Thank You! I needed a good laugh and that was just it.
 
Rick Inman:
It's kinda like this:

If you pack in a bunch of foam rubber into a tank until it's full, then stuff the same amount again into the tank, as you later remove the foam rubber, the remaining foam expands, keeping the tank full of foam rubber even when it's half filled.

So for now on, if you complain to you're LDS that you didn't get a full fill, he can say, "Yes you did. What else is the tank full of?"


Well there went that mouthfull of wine all over the keyboard !!!:D
 
https://www.shearwater.com/products/perdix-ai/

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