Single Cylinder - two complete regulators?

[Mo2vation]

OK - me again. The public humiliation continues...

BP is in. Fundamentals book will be in Monday - so if all of this is in the book and I'm jumping the gun, smack me later.

I see a lot of gear pix where the single cylinder on a BP&W has what looks like a manifold with two separate first stages and second stages (long hose and necklace) on a "T" type manifold assembly.

Is there a benefit to this (two first stages, as opposed to two hoses off one first stage) or are these doubles divers just using a single with their doubles manifold?

Clueless in So Cal.

(Ken)

 

[AzAtty]

The valve you're seeing is most likely a "H" valve. It allows the attachment of two independent regulators and has two independent shutoffs. The idea is redundancy on a single cylinder. If you have a catastrophic failure of the primary regulator (or even a bad freeflow situation), you can cut the gas flow to the primary and breathe off your backup. It's the same concept as diving a set of doubles, but modified for a single tank.

 

[O-ring]

Mo2vation once bubbled...
OK - me again. The public humiliation continues...

BP is in. Fundamentals book will be in Monday - so if all of this is in the book and I'm jumping the gun, smack me later.

I see a lot of gear pix where the single cylinder on a BP&W has what looks like a manifold with two separate first stages and second stages (long hose and necklace) on a "T" type manifold assembly.

Is there a benefit to this (two first stages, as opposed to two hoses off one first stage) or are these doubles divers just using a single with their doubles manifold?

Clueless in So Cal.

(Ken)

...what you are describing is an H valve. It basically allows a single cylinder to have redundant first stages. Needless to say, in the case of tank neck o-ring failure you are still SOL, but it is a redundancy improvement over a standard single cylinder setup with one first stage.

Some divers who dive doubles will do a single with an H valve for their second dive because it allows regulators set up for doubles to be attached directly to the tank without modification (switching hoses over and attaching seconds to one first, etc.).

 

[metridium]

I dive my 104s either as doubles or as H-valve singles for the reasons AzAtty and Oring mentioned.

 

[Mo2vation]

first off - woah. You guys are johnny-on-the-spot.... I mean, the pixels hadn't changed color yet and *boom* you reply

This board rules.

I got it. So it serves as a redundancy issue as well as an ease of set-up issue. Very cool. If I was a doubles guy, I'd love the quick change from explorere to Pioneer, peel off a cylinder and I'm ready to join the Kelp Kickers...

Seeing as I'm 100% single cylinder, I'll stick with my Atomic B1. I need to get another second stage (for the BP&W trial rig I'm building) cuz I'm not going to transfer over the Airsource to the wing. I can't see me needing an H valve or anything.

Thanks -

Ken

 

[WJL]

It's not a problem to use a single first stage with the BP/wing setup. If you're going to buy a new one for your setup, just make sure the first stage has enough ports to supply everything you need: primary second stage, backup second stage, SPG, inflator hose, and drysuit inflator (if you have a drysuit).

 

[metridium]

Mo2vation wrote...
I can't see me needing an H valve or anything.

Probably not....unless you're a beginning cave student (with some of the agencies), solo diver, or you've had a first stage fail before.

I fall into category #3.

and maybe #2.

 

[Mo2vation]

Tha's a scary thought - my understanding is I have a better chance of the Cap't going Hazlewood on the breakwater and tossing us all in the drink on the way to the dive site than I do of a catastrophic failure of my 1st stage during my guppy OW diving.

Youre giving me the heebe jeebies...

k

 

[metridium]

Mo2vation wrote...
Youre giving me the heebe jeebies...

k

No worries, most likely.

Just stay close to a reliable buddy, observe Rock Bottom protocol, and a failure shouldn't make a difference. It will curtail your diving until you can get a replacement or repair, though.

BTW, this was on a guppy dive....well, a rec dive anyway.

Now you've given me a disturbing thought...I have had a first stage failure...does that mean I'm up for a Hazelwood experience?

 

[Diver0001]

metridium once bubbled...
Probably not....unless you're a beginning cave student (with some of the agencies), solo diver, or you've had a first stage fail before.

I fall into category #3.

and maybe #2.

I fall into #2 from time to time but I actually use redundant 1sts because I often dive in near freezing water. In the event that I need to offer my buddy a reg I want the load spread across 2x 1st stages to avoid a freeze-up.

R..