Shutdowns on twins.

[daz]

<font color='#000080'>Can someone give me a step by step shutdown procedure for manifolded twins. &nbsp; Anything I can use for practice drills would be much appreciated.

Daz

[And]

<font color='#0000FF'>Hi

1. Signal to buddy to watch you.
2. Check backup reg with a little push of the purge button
3. Close Right post (Right hand) and then breathe it down
4. Swop to backup reg, clip off primary long hose
5. Open right post (important, this is a common error!!)
6. Close and then open isolator
7. Check primary reg with a little push of the purge button
8. Unclip Primary Reg, Close Left post and breathe it down
9. Swop to primary reg, check backup hose with a little push of the purge button
10. Signal to buddy that you're OK

Congratulate yourself on a job well done

Also at the buddy check and during the dive do a flow check

1. Right post open and can close
2. Isolator Open and can close
3. Left post open and can close
4. Stages closed and can open

Hope that Helps

WL

[Dominic]

Why exactly do you want to breathe all the air out when you've shut down a valve?
Water can enter the system if there's no air, and O-rings are most likely to blow when you pressurise the system..

[And]

<font color='#0000FF'>Well...

A valve drill is a simulation. Usually you would just do a flow check during a dive and so you wouldn't normally do it.

However in a real situation such as a freeflowing right post (most common situation as this is the post doing the work) you would shut down and change regs. After you shutdown you would have no air and so it becomes natural when you have experience of breathing a shut down reg.

It also ensures that you have opened the valve properly because you check each reg after you have opened it by tapping the purge. If there was air still in the system then you would not know that it was fully operational and this could cause a major event, I did point out that a common error is to shut the right post and then go straight onto the manifold which is what I did the very first time I did a valve drill, luckily my buddy pointed it out before it became a problem.

The left post is most likely to get rolled off during a dive and so the same logic applies.

Kindest Regards

WL

PS Sorry forgot to say that a valve drill is done at a safe depth like 6 mtr just in case an oring goes like dominic suggested.

[Gavin Yates]

<font color='#000F22'>I would say that it's a folly to clip off the primary reg.

What happens if someone needs your air? The come belting in and grab the reg to find it connected to a d-ring.

IMHO - just leave the reg around your neck whilst you breathe the secondary. Also I would not advise using the purge buttons at all.

There are three main senarios to consider.

1. Primary is free-flowing/bolloxed - action &nbsp;- swap to secondary and shut down primary. Then re-open primary.
2. Secondary is freeflowing/bolloxed - action - as above in reverse.
3. Your SPG hasn't moved - check secondary - could be that manifold is closed? - open manifold - check SPG again - and bollock yourself for being a tw*t.

I agree it well worth while making sure that everything is in order - valves open etc on the 6m check. Don't dive a manifold with isolator if you can't reach it.

[And]

<font color='#0000FF'>Hi

Gavin, we are talking about a valve drill, which should mean that your buddy would have his ducks in a row and won't need your air for the few seconds it is clipped off. If so you are diving with the wrong buddy!! Clipping off the long hose is good housekeeping so it is there when you want it and not dangling behind you or causing a nuisance. You would clip it off when using a stage or when you are out of the water so it makes sense to get used to clipping it off whenever it is not in use. Its part of the 'muscle memory'.

Just like tapping the purge button of the reg you are swopping to BEFORE you close the valve prevents you from closing a valve and then finding out that your left post has rolled off or that you forgot to turn it on before your dive.

There are actually 9 possible faults that can occur with a manifold aside from poor diving skills. A diagram can be seen on Howards site which is adapted from GUE's tech1 course http://www.bitz.fsnet.co.uk/bitzmani...iluremodes.htm

But anyhow its up to you the way you do it, I just gave my opinion. Perhaps you can go through your better technique and we can all pick holes in that or adopt it in our diving

Kindest Regards

WL

[Gavin Yates]

<font color='#000F22'>Hey Lettuce - It's only my opinion.

Yes, buddy should have &quot;ducks in a row&quot; but OOA situation can happen at any time and it might not be my buddy that comes screaming in for air it could be another member of the dive team.

Also - I would advocate not clipping off your primary when you've moved to your deco gas. You buddy could o2 tox and easy access non-deco gas could save his life.

If you're diving the long hose then it shouldn't be waving in the wind but under the right arm, round the neck and hanging in the triangle.

If you want to check that a post hasn't rolled then reach behind and feel for it. Purging is never a good idea in cold water unless you really need to. Also If the post has rolled and you tap the purge it'll flow and you'll think everything is fine - then you'll go to breathe of it and get diddly.

There are many failure possibilities - I was just outlining the most common ones.

All I would say is do whatever you're comfortable with but remember to check the back-up reg on the dive every now and then cos you don't want it failing when you need it. The easiest way to check is to breathe off it.

Again - just my views - not necessarily the right ones!

[And]

<font color='#0000FF'>Hi

I don't want to hijack the thread and I hope Daz has enough info to come up with a drill he can use. Let me clarify the circumstances in which you should IMHO, do a valve drill.

In my opinion a valve drill is planned as part of a training dive, done in the first stages at a shallow depth with no deco obligation. This means you can always do an ESA (Emergency Swimming Ascent) It is not done during a dive with other objectives. That just needs a flow check and checking your backup as Gav suggested. This negates the point about needing to donate air to anyone. If there is an emergency from someone other than your buddy then surely your buddy will handle it (question: where the f**k is their buddy ?!!). If your buddy can't help because they can't see them then you will have time to react because they are approaching from behind your buddy. I really think that its an issue that is not worth planning for as it is so unlikely. We are talking about a VALVE DRILL of which the sole aim is to determine that you are able to operate your valves in an emergency. We don't try and plan for donating air when we remove and replace our mask do we ? Then why do we have to make a valve drill so complicated.

This is a response regarding clipping off the long hose.

Regarding not clipping off during deco. Assuming you are on the same gasses and are at the proper depth then Ox Tox is unlikely because you would be toxing too. However I am sure that a toxing buddy will not be asking you to donate air but effectively having a fit right in front of you! The only reponse to this is to ensure their reg stays in their mouth (because they will spit it out) if you can and get up to the surface. Even if they stop convulsing at a shallower depth it is common for them to have a second convulsion. I seriously doubt that you will be able to donate in that situation as that might introduce water into their airway.

Again it is a case of overthinking and creating problems. You always donate what you are breathing and go to backup. It is that simple. Clip off your long hose when it is not in your mouth. It is that simple. When you make diving simple it makes it more enjoyable in my opinion.

Hope that helps

WL

PS I wasn't being nasty or anything Gav, its just that you said that what I recommended was 'Folly' so I thought I'd play a little.

[Gavin Yates]

<font color='#000F22'>Ok we agree to differ.

My view is always be ready for anything and other people's buddies do go missing so they might just come screaming into you for gas.

You say that if they're otoxing then you probably would be too. Not true - different people haven't different levels and again it might not be your buddy but someone else.

You don't plan to be able to donate whilst in mask off situation but you should be able to cope.

Anyway, having to spent the weekend having had various different OOA and mani failure drills thrust upon me I'll stick with my way and remain upclipped under the water. It was in my training to do do this and I still concur with that.

We all train for unlikely events - broken harness - complete failure of rig and emergency swim to buddy - hole in wing and drysuit - is it being over-complicated or planning for the worst case.

I agree with you that keeping it simple is the best thing one can do.

BTW I meant no offense by using the word &quot;folly&quot; it is very mild.

Keep well

[Mark]

<font color='#000080'>

Originally Posted by [b

Quote[/b] (wetlettuce @ April 29 2003,12:04)]Flow check

1. Right post open and can close
2. Isolator Open and can close
3. Left post open and can close
4. Stages closed and can open

3.5 Unclip SPG, check it then reclip.