What's the deal with H-Valves?

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Some dive boats discourage divers from bringing doubles on rec-only trips, as they take up space. So that leaves relying on a buddy, a pony tank or, I suppose, an H-valve to address the redundancy issue.
 
On a recent cold deep dive, 5 of 10 people in the water had free flows. 2 of those 5 were caused by the extra load on the 1st stage from buddy breathing. The problem resolved above the thermocline. My preferred solution on these dives is a 40CF pony.
Wouldn't a better solution be to use a first stage which isn't prone to free-flowing in cold water? Like, say, a good quality diaphragm 1st?

I've had my share of 2nd stage freeflows during winter diving. All of them at the surface, BTW. Never experienced, never seen a 1st stage freeflow. But then I and all my mates may just have been exceptionally lucky...
 
Wouldn't a better solution be to use a first stage which isn't prone to free-flowing in cold water? Like, say, a good quality diaphragm 1st?

I'd vote for a qualified travel agent booking a trip to places with water / air temps several degrees above 0 C :)

Here's a link to the beuchat Y valves. I'd guess they are 25mm, but it looks like they may be made to order.

Beuchat 2 Outlets Valve with SAS [Safety Air System]

Tobin
 
Some dive boats discourage divers from bringing doubles on rec-only trips, as they take up space. So that leaves relying on a buddy, a pony tank or, I suppose, an H-valve to address the redundancy issue.
that's when you ask them how they take up more space than a pair of tanks and a pony bottle....
 
that's when you ask them how they take up more space than a pair of tanks and a pony bottle....
They take more space on the set up benches where space is usually at a premium. Usually lots of other spots to store the second tank and pony.
 
Ponies do seem to take up space on a boat, though not as much as doubles. That's one (minor) reason I'm not keen on ponies. Of the various options for redundancy, I have chosen the philosophy that my buddy provides my redundancy.
 
I'd vote for a qualified travel agent booking a trip to places with water / air temps several degrees above 0 C :)
Some folks can afford that. Others can't, dive at home and use suitable gear for that
 
Wouldn't a better solution be to use a first stage which isn't prone to free-flowing in cold water? Like, say, a good quality diaphragm 1st?

I've had my share of 2nd stage freeflows during winter diving. All of them at the surface, BTW. Never experienced, never seen a 1st stage freeflow. But then I and all my mates may just have been exceptionally lucky...
I use Apeks regs and have (knock on wood) never had a free flow, diving down to 3.3C, my coldest dive. DS4 with ATX 40's and DST with TX 50's. I believe all of those that had free flows were using ScubaPro regs, not sure of the flavours. But I don't believe it was an equipment problem. As I said earlier, it was largely complacency. This is not a regular occurrence with these folks, quite unusual in fact. I know one, at least, made the simple mistake of adding air to her drysuit while breathing in @130 FFW, 4C. Her buddy free flowed when she went on his second and took several deep quick breaths, by the time that happened they were about 90 FFW, it resolved when he hit 70 FFW.

The real solution is to not let it happen in the first place. If it does, I still contend a pony creates less risk for the team than sharing air off of the same 1st stage.
 
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I'd vote for a qualified travel agent booking a trip to places with water / air temps several degrees above 0 C :)
Tobin

We have a winner!!!!!!!!!!!!!!! :cheers::cheers::cheers:
 
I'd vote for a qualified travel agent booking a trip to places with water / air temps several degrees above 0 C :)
Tobin
By doing that I would have missed some of my favourite dives. Off to Greenland on Saturday, no hurricanes there.
 
https://www.shearwater.com/products/swift/

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