The 'tricks of the trade' column...

[A. Berk]

Originally Posted by Divingchef

Hullo Berko

First of all, thanks for starting this thread, its very informative.

As I'm a mere "sports" diver and therefore dont know any better !!

How does the neck dam work on a hard lid ??

I am assuming its some sort of inverted neck seal,,,,

Cheers

Chris

Chris, you are correct, the seal on the neck is exactly the same as a suits and should (as far as Kirby Morgan's go) be laid upward toward the head in case of the unlikely (?) event that you lose gas through an umbilical rupture and the helmets non-return valve fails. In such an instance (in theory) the 'inverted' neck-dam would allow the helmet to flood rather than suck your eyeballs out . The attachment of the neck-dam to helmet may be either a 'cam' action clamp or 'O' ring seal dependent on helmet type.

With regard to the non-return valve remember that they may sometimes get some shitty gas and moisture pass through them and residue can clog the valve. Therefore one should always give a 'blow and suck' test on it to prove its function before fitting the umbilical to the hat. If you can suck the mearest amount through the NR valve - change it out!

All the best,

Berko

[Divingchef]

Cheers for that always wonderd how the hard hat works.
It seems so alien not to have a reg in mouth !!

Chris