Gas planning

[Kelly Jessop]

1 minute 30 seconds. That is how long it takes for a 3300psi 120 cuft tank to empty with a blown burst disk.

[Capt Tom McMillan]

Kelly,

I think that Kurt Bowen did a very good study on catastropic gas failures, just give him an email and he will let you know his findings. I don't know if he did those big gorilla tanks or not but I am sure you can extrapolate his findings to correlate to your big tanks.

By the way, did you have a burst disk fail????????

[aw]

All the more reason to double the damn things and not worry about it. ; )

[Gary]

Curt Bowen posted these failure test results in Febuary over on The Deco Stop:

Very interesting:



Here is a little test I did at Eagles Nest cave on Feb 12th for a small article to be placed in issue 17 of Advanced Diver Magazine.

The question I wanted to answer was:

How much time would it take to empty a full aluminum 80 cuft cylinder from 3000 psi to 0 for the following situations and would depth affect the times.

1. Failed Burst Disk
2. Failed HP Hose
3. Failed LP Hose
4. Free Flow high performance regulator 2nd stage.

I completed the test on the surface (0 feet) with 4 aluminum 80’s and a Zeagle D50 regulator.

Here are the results

1. Failed Burst Disk = 72 seconds
2. Failed HP Hose = 22 minutes
3. Failed LP Hose = 83 seconds
4. Free Flow High Performance Regulator = 255 seconds


I then repeated the test at 4 atm’s / 99ft

1. Failed Burst Disk = Same within a second or 2
2. Failed HP Hose = Same within a minute
3. Failed LP Hose = Same within a second or 2
4. Free Flow High Performance Regulator = 155 seconds

I then repeated the test at 8 atm’s / 231ft

1. Failed Burst Disk = Same within a second or 2
2. Failed HP Hose = did not complete due to time restraints but would assume it would be with a minute difference
3. Failed LP Hose = Same within a second or 2
4. Free Flow High Performance Regulator = 91 seconds

[Kelly Jessop]

All the more reason to double the damn things and not worry about it. ; )
Makes you think though. If a single 120 takes 1min 30 seconds,then a manifolded set of 104's with open isolator will be under 3 minutes. Lets say a burst disk blows with partially full tanks. By the time you overcome the surprise of the event,figure out what the problem is,and shut down the isolator;just think how much gas you lost in each tank,considering one tank will be completely exhausted.

[MikeH]

Makes you think though. If a single 120 takes 1min 30 seconds,then a manifolded set of 104's with open isolator will be under 3 minutes. Lets say a burst disk blows with partially full tanks. By the time you overcome the surprise of the event,figure out what the problem is,and shut down the isolator;just think how much gas you lost in each tank,considering one tank will be completely exhausted.

That's one of the reasons I dive sidemount....no single failure can cripple me. This also alleviates my dependence on others to get me safely out of the cave should something like this(or a manifold failure) occur right at thirds/max penetration. Not likely...but possible.

Mike

By the time you overcome the surprise of the event,figure out what the problem is,and shut down the isolator;just think how much gas you lost in each tank,considering one tank will be completely exhausted.

Going back to my first cavern class, isn't this why my buddy reserves one-third of his/her gas for me?

Russell

[John L.]

You should practice valve shutdowns on all your dives during deco. A good buddy should'nt have to ask for a reg.