TDI Valve Drill sequence?

[Mark Powell]

TDI don't mandate a particular sequence for the shutdown.

If a candidate has already practiced and is familliar with a particular shutdown style, whether it is isolate first or the GUE style right post first, then as long as it is safe I am happy for them to continue to use this style. I don't want to make someone change a shutdown style they are happy with and have practiced as this is more likely to confuse them and get them doing a mixture of both.

This is common at the more advanced levels where someone has already been diving twins for some time, has repeatedly practiced a shutdown and have built up muscle memory.

For some of the earlier courses, where candidates haven't learnt a shutdown drill I will discuss the main options and let people try both and decide which they prefer.

If someone asks me which I prefer then I will describe the isolate first procedure. The reasons for this are;
- By isolating you save half your gas
- The fault identification part of the drill lets you determine where the problem is and fix it if possible
- You are never left without breathable gas in your mouth
- The drill and the actions to be taken in a real situation are the same, this reinforces muscle memory

[Paul r h]

Originally Posted by Mal Bridgeman

I would follow the advice of choose a method and stick with it. If you think one day you might do GUE training then I would go for that method.

When I did my initial TDI training with Mark the sequence and technique was different.

1. Close Isolator
2. Close RH post (don't breathe down)
3. switch to backup
4. Clip off primary
5. Open RH post
6. Close left hand post (don't breathe down)
7. Unclip Primary
8. Switch to primary
9. Open left post
10. Open Manifold
    
11. Flow check

The GUE one is well described on the Team Foxturd pages and as I understand it the primary difference, other than sequence, is that GUE will attempt to fix a faulty 1st stage so the dive can continue, whereas the TDI method seemed aimed at training you to secure at least half your gas to perform your ascent.


HTH
Mal

Nice to see someone has pointed out(dont breathe down) keep it pressurised,no point in running the risk of getting water into the first stage.
Why is it people are of the opinion they have to breath a reg down when they shut down the post?I have heard a few people say this is what they do, i cant see any posative reason for doing so,am i missing something

Paul.

[ardhill]

Originally Posted by Paul r h

Why is it people are of the opinion they have to breath a reg down when they shut down the post?I have heard a few people say this is what they do, i cant see any posative reason for doing so, am i missing something

My understanding is that it is to identify where the problem is.

If you do not breath a reg down then gas will still escape from the fault area till it is depressurised, meaning that you cannot be sure you have shut the right bits down, or maybe you have closed the manifold when you didn't need to.

This could be wrong and the bubbles may stop just as soon as you stop breathing it, thankfully I have never actually had a 'real' situation to know.

If someone tells me that the bubbles will stop as soon as you shut down and stop breathing, then I am happy to switch regs ASAP and not wait till it is breathed down.

[String]

I was taught right post first with my TDI course although the instructor did mention there were other ways but he preferred that one but there was no right or wrong. Same with other aspects on the course related to kit config and so on - TDI seemed to have a work with what you've got rather than just tell you things must be done with this and that way etc.

The theory being if you know for certain where its coming from (reg in gob freeflowing, right post, reg under neck freeflowing, left post, anything else or unsure then isolate and work it) you can save more than half the gas.
Others obviously disagree.

I did it his way as it was the first way i was taught. I reserve the right to reconsider and possibly change my mind at any time though

[Paul r h]

Originally Posted by String

I was taught right post first with my TDI course although the instructor did mention there were other ways but he preferred that one but there was no right or wrong. Same with other aspects on the course related to kit config and so on - TDI seemed to have a work with what you've got rather than just tell you things must be done with this and that way etc.

The theory being if you know for certain where its coming from (reg in gob freeflowing, right post, reg under neck freeflowing, left post, anything else or unsure then isolate and work it) you can save more than half the gas.
Others obviously disagree.

I did it his way as it was the first way i was taught. I reserve the right to reconsider and possibly change my mind at any time though

Agreed works for me.
When i did my TDI stuff the instructor held up flash cards with various scenarios ie first stage problem on primary ,back up second stage problem.I found this worked a lot better than performing a standard drill as it put the emphasis on dealing with the problem directly as appose to going through unnecessary shutting down of unaffected components.As String said,if you are not sure as to where the problem lies,Isolate and figure it out.

[String]

Originally Posted by Paul r h

When i did my TDI stuff the instructor held up flash cards with various scenarios ie first stage problem on primary

Probably against standards (i have no idea) but i did my course abroad and wont say where in case instructor gets into trouble. No flash cards. Things just happened (shallow water, no deco obligation obviously). Masks vanished off heads, regs suddenly stopped giving gas, things started freeflowing and so on. The drill i was taught worked in those situations at least.

I can see logic in the isolate first for sure but i can also see value in the opposite method.

[ardhill]

Post Deleted

Ignore me, I should learn to read better.

[Mark Chase]

Originally Posted by ardhill

Does the TDI have a particular sequence for their shut down drill or do you just faff around till you have cover all the knobs in your own way?

I mean do you have to do say:

- Main Reg off
- Isolator off
- Breath reg down
- Switch reg to back up
- main reg on
- back up reg off
- Breath it down
- switch to main
- Isolator on
- back up reg on

Or similar or does it not matter too much in what order it is done?

Thanks
.

This sequence of events is crap and nearley killed me. I wouldent use it again.

NEVER breath down a reg, its a stupid bulshit idea from the old GUE training days. I beleive they changed it before they sucessfulley killed someone.

ATB

Mark Chase

[GLOC]

Originally Posted by Mark Chase

This sequence of events is crap and nearley killed me. I wouldent use it again.

NEVER breath down a reg, its a stupid bulshit idea from the old GUE training days. I beleive they changed it before they sucessfulley killed someone.

ATB

Mark Chase

Mark, the primary is still breathed down as part of the valve drill but you do not breathe down the secondary, this is purged whilst the primary is in the mouth.

Edit: The process in your quote is not the old GUE one either as you never closed the isolator when a post was shut down.

Whenever I put a reg back in my mouth, primary, secondary or stage reg, I give it a quick purge to ensure that there is no water in the mouth piece. Haven't had an issue yet, and hopefully never will. However, I do remember that in Stoney I did get a small mussel stuck in the backup diaphram and it breathed very wet. Signalled to buddy that there was an issue and was breathing from their long hose while I took the plate off

Regards

[milldog]

Originally Posted by Mark Chase

This sequence of events is crap and nearley killed me. I wouldent use it again.

NEVER breath down a reg, its a stupid bulshit idea from the old GUE training days. I beleive they changed it before they sucessfulley killed someone.

ATB

Mark Chase

I think and i may be wrong here that they teach breathing down the reg because the team look to fix the problem and by doing this they take the pressure off the 1st stage enabling you to tighten or remove and replace the stage.

However i could be talking balls and some GUE/DIR diver will put me straight

Graham