[Garf]

Hi Graham, some good questions there. I will answer them but remember I am answering from my own perspective, rather than any "official" DIr position. Additionally, there is nothing "wrong" with however a valves drill is done, there are always different ways to remove the skin of a domesticated feline. As always, all I am trying to achieve is to disperse the myth that DIr information is secret handshake stuff, and explain why WE choose to do something in a particular manner.

I understand that you shut the right post down first as this is regarded as the primary post and most likely to fail. But i have had the valves leak behind my head in the shit and i couldn't tell which valve it was, in that case wouldn't it be better to isolate the manifold first and then the right post and so on.

Yes, 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.

also with a valve problem signalling to the team and getting them in position would waste time and loss gas, i know this drill has been discussed on the DIRx forum with quiet a few positive suggestions.

Well, I would reiterate this is a drill. In a real siutation, it is handled differently. Scootering around Stoney a couple of weeks ago my backup freeflowed. I signalled to the team and went into the process of resolving the situation. by the time I had shut down the left post both Gareth and Howard had dropped their scooters and got into position ready to assist. the valve drill in DIR, as with all DIR drills, is not something an individual does, as in a TDI valve drill, it is a team drill. All the valve drill does is build muscle memory to enable you to go through the process quickly, calmly and without undue panic or stress. All drills do that, so any drill that helps you build that memory is a good thing, whichever particular flavour of valve drill you adhere to.