What the heck is a H valve?

[Matt P]

I've recently decided I'd like to start diving with a redundant air source. I always thought that meant 2 options: pony or doubles. Someone suggested that I could use an H valve instead.

So - what the heck is an H valve & what does it buy me? Is it a good alternative?

 

[Mo2vation]

I've recently decided I'd like to start diving with a redundant air source. I always thought that meant 2 options: pony or doubles. Someone suggested that I could use an H valve instead.

So - what the heck is an H valve & what does it buy me? Is it a good alternative?

It offers redundant First stages.

Imagine a doubles manifold run through a trash compactor so it would fit on a single tank.

You have 2 first stages. Like a doubles rig. But they're both on a single tank. No redundant gas supply - just redundant gas delivery equipment.

What are you doing that makes you want to dive a redundant gas source?

---
Ken

 

[Matt P]

Thanks for the reply and the picture.

It offers redundant First stages.

Imagine a doubles manifold run through a trash compactor so it would fit on a single tank.

You have 2 first stages. Like a doubles rig. But they're both on a single tank. No redundant gas supply - just redundant gas delivery equipment.

So that means that instead of an octo with 2 regs on it I have (essentially) 2 valves coming off a single tank? Is there an isolator to turn-off one of the regs?

Hmmm..it sounds like it doesn't really offer very much. I'm still in trouble if an O ring blows on my tank or I hit an OOA situation. Is there some benefit I'm missing?

What are you doing that makes you want to dive a redundant gas source?

I'm preparing for my first dive off of NJ.

 

[Mo2vation]

Thanks for the reply and the picture.



So that means that instead of an octo with 2 regs on it I have (essentially) 2 valves coming off a single tank? Is there an isolator to turn-off one of the regs?

Hmmm..it sounds like it doesn't really offer very much. I'm still in trouble if an O ring blows on my tank or I hit an OOA situation. Is there some benefit I'm missing?



I'm preparing for my first dive off of NJ.

My buddy is my redundant gas supply.

Personally, I don't see the benefit of adding an "H" valve. Others may.

To me, adding another first stage means just another machine to get between me and my gas, you know? I have hundreds and hundreds of dives on my one first stage (with two seconds) and its performed perfectly. Adding another first stage to the mix without adding a true redundant gas supply doesn't make sense to me.

But I'm an open water weenie.

---
Ken

 

[Tsalagi]

The real benefit is 2 first stages. Of course this implies that if a first stage does blow out or malfunction that you turn off the correct valve.

 

[Mo2vation]

The real benefit is 2 first stages. Of course this implies that if a first stage does blow out or malfunction that you turn off the correct valve.

I don't see the benefit of having two first stages, with only one tank. I mean maybe back when this technology was new and still a bit dodgy. But now? Who dives these things anymore? I've seen one pair diving this rig in the last 3 or 4 years.

---
Ken

 

[Matt P]

I don't see the benefit of having two first stages, with only one tank. I mean maybe back when this technology was new and still a bit dodgy. But now? Who dives these things anymore? I've seen one pair diving this rig in the last 3 or 4 years.
Ken

Yeah - that is what I'm thinking, too. I'm a newbie so maybe there's something I'm missing. Otherwise, I guess it's back to the ole pony vs doubles debate.

 

[BIGSAGE136]

Think deep & solo. Not only does an H valve give you a redundant 1st stage, it also allows to isolate either one.

 

[H2Andy]

the advantage of the h-valve over a regular valve is that you can have two independent first stages. that way, if one first stage blows on you, you can
switch to the other.

the disadvantage of the h-valve when compared to a double tank setup is that
if there's a problem with the burst disk(s) on an h-valve or if something goes wrong
with the seating of the insert itself, you lose both regulators. with a double set up,
you'd still have one tank functional if that happened.

 

[Tsalagi]

The only real benefit is the redundent first stages.

My cavern/'cave intro' class required either H valve or doubles with isolating manifold so you'd have 2 first stages. I agree though, for the most part there is no real benefit -- other than redundent first stages.