knobs on knobs off .....

[liamm]

I've learnt a few knob related things recently, mostly by things going a bit wrong. The discussion on knobs open or turned back prompted me to drivle this.

Up until recently I’d been diving with my manifold shut, and then opening every once and a while to balance the cylinders. I’d been warned that this could cause a free flow as the pressures balanced.
Whilst on the shot line in on a dive in December on I looked at the spg and was a bit worried that it was down to 70 bar (twin 12s 30 for 20min). I realised that id not equalised cylinders. So i reached round and twiddled with my knob and both regs free flowed - it was an easy fix as they stopped once id closed and reopened each post. So from now on i keep the manifold open.

Regarding the valve a bit closed option that cropped up on another thread. I've only been badly narked twice, once I panicked because I thought my comp said I had 14 mins of deco to do when it was really saying I had 14mins of no stop time, an easy panic that I got over and then was a bit freaked about. A more difficult problem arose recently when I was at 30ish meters on air and a bit foggy. I thought that I was having problems drawing an easy breath so reckoned that my valves weren’t fully open, (up to this point id been opening them and then turning them back a half turn) i reached around and checked the valves and both seemed to be only open a crack so I opened them the rest of the way. Well I though I did, in fact id closed them. One breath later I nearly turned myself inside out trying to draw a breath. Again this was quickly sorted but it made me think a bit.

So…. What I’ve learned …… leave the manifold open, its easy for me to shut down (inverts) and is actually less task loading. Open valves fully and leave them open fully.
What helped me in both incidents was that id signalled to a buddy to watch me as something was wrong. The buddy had a long hose and this made sorting it out easier. It also allowed him to point and give me a tosser sign when he realised that id turned off my own air.

Any way, there you go something I’ve learned from and twenty mins of time wasted when I should have been marking homework.

[Peter M]

Originally Posted by liamm

So…. What I’ve learned …… leave the manifold open, Open valves fully and leave them open fully

Sounds like a plan to me !

[Garf]

The problems you described were not caused by a failure in a process, they were caused by a failure in your brain - narcosis.

What I'd learn from this is that narcosis is a dangerous thing, and can hit at suprising shallow depths.

[Twinsetmad]

I was a Chepstow...sitting one out as my buddy went in with the AI to do his depth progression... and along came a gang of guys with an instructor to do a Trimix/ deco course....

The instructor told the guys to do there buddy checks ... all were on twins but one guy on a single...

As part of their buddy checks they made sure their cylinder valves were fully open... I watched in disbelief as the guy with a single fully turned off the right hand post on his buddies twinset....I watched for a few minuites to see if he'd spot it, but had to go and sort them out.. I realise that the guys were probably all excited and a bit destracted.... but it could have been a problem...

[Madfish]

Originally Posted by Twinsetmad

I was a Chepstow...sitting one out as my buddy went in with the AI to do his depth progression... and along came a gang of guys with an instructor to do a Trimix/ deco course....

The instructor told the guys to do there buddy checks ... all were on twins but one guy on a single...

As part of their buddy checks they made sure their cylinder valves were fully open... I watched in disbelief as the guy with a single fully turned off the right hand post on his buddies twinset....I watched for a few minuites to see if he'd spot it, but had to go and sort them out.. I realise that the guys were probably all excited and a bit destracted.... but it could have been a problem...

Thats confusing - where on earth does it say that a buddy touches or otherwise interferes with his buddies kit on a buddy check? Unless specifically requested by the kit owner to do so? And more worryingly at that level, the divers should be more than capable of manipulating their own valves...........

Di

[liamm]

Originally Posted by Garf

The problems you described were not caused by a failure in a process, they were caused by a failure in your brain - narcosis.

What I'd learn from this is that narcosis is a dangerous thing, and can hit at suprising shallow depths.

in the case where i misread my computer and panicked i think the narcosis was heavily influenced by overexertion / CO2 buildup as id had to fin hard to deal with a current and then descended like a brick.