Thanks for the post Garf, very informative.
Garf you know me well enough not to take the following the wrong way, but I still have some problems about the logic involved in the drill, and would be genuinely grateful if someone could clarify ....
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| Originally Posted by Garf we shut down the right post as that is the most likely to fail. And agreed sometimes you cannot tell where the bubbles are coming from.
But to some extent we are playing the numbers. We know that gas is leaking from somewhere. If we shut down the isolator and it is the isolator that has failed, then the gas is going to continue to leak out and we have gained nothing. We shut down the right post becuase that IS the most likely to fail and if we shut it down we will limit the amount of lost gas. Its down to a difference in how you approach the problem. The "isolate first" school of thought basically involves reserving half the remaining gas. The DIR school of thought is more to do with diagnosing the problem, and closing the isolator first gives us no feedback about the nature of the problem if the bubbles do not stop. If we agree that the failure can be either one of the posts. It's almost certainly not going to be the left post, as that is sitting around your neck not under stress, and a left post failure is usually obvious from the location of the bubbles. that means its likely to be the isolator or the right post. If the isolator has failed you are going to lose all of your gas anyway. So you might as well go for the one that is most likely to have failed, and already start learninig about where the failurer has occurred. |
Crystal clear, if the source of the problem isn't known...shut the post most likely to have caused the problem. Now you know if it is the problem, reopen if it isn't, OK...
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| Originally Posted by Garf We have already disgnosed that the right post is not the cause of the problem. that leaves the junctions between the manifold and left and right posts, the isolator, and the left post. |
With you so far...
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| Originally Posted by Garf If we isolate at this point, we limit the escaping gas if it is either side of the manifold. closing the isolator will keep the gas in either side of the set, whichever side has failed. |
Whilst this is true, it was also true at step 1. For the same logic you applied in chosing to shut down the RHS first rather than isolate, I think you should shut the LHS post next. Indeed, I think you already know this.....
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| Originally Posted by Garf The isolator itself we can do nothing about if it has failed.The gas is going to go. |
So why waste time shutting it? If it wasn't the RH post, the left is the only thing you can do anything about so surely this should be shut next?
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| Originally Posted by Garf that then leaves us free to diagnose the left post. |
Whoa, back up there. You shut the RH post = lets say its not the problem. You've already said that leaves the manifold which you can do nothing about or the LH post - You have already diagnosed this just by shutting the RH post..... or did I miss something??
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| Originally Posted by Garf Remember this is a drill. would I open the isolator immediately after closing it. No. This is a drill to build muscle memory, not to replace the thought process of diagnosing a problem. |
I know it is a drill, but drills do more than just build muscle memory - they aid in calming a dangerous situation because you just F'n do it - you know its the right thing to do and you do not have to engage the brain. I personally go all weak kneed at the sight of blood, but I have treated some gory first aid incidents by reverting to drill.
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| Originally Posted by Garf The GUE approach is completely different, more about diagnosis and understanding. If I can't save the gas it's no biggie anyway. everyone else in the team has enough gas to get them and me to the next gas source. |
Now I am confused. If I follow this last piece of logic, why do you use twins with all those extra failure points? If the team has enough gas anyway??