All about H-valves and Y-valves

[globaldiver]

I actually ended up purchasing two PST E8-130s, and a Halcyon manifold.

I still have an OMS H-valve on a Faber HP 120, but I rarely use it today since I try to dive with my doubles as much as possible (training DIR exercises from my DIR-F class)

Sincerely

Anders

 

[Chris P. D.]

I was wondering if someone could explain to me what's the purpose of an H-Valve? Except for having two 1st stage and 2nd stage regulators going off one tank what's the point especially if you have a blow out in the O-ring going to your primary first stage? It's not like you can isolate it from your primary or can you? I've only seen pictures of one and not actually used one so that's why i'm asking.

 

[drbill]

An H-valve is considered a backup if your reg should malfunction. You are absolutely correct (IMHO) that it will not help in the event of a tank-related problem. For example, my tank valve had a debris clog last year and all air flow from the tank ceased. An H-valve would leave me dead in the water under those circumstances. That is why I prefer a totally redundant system (twins or pony) instead.

Dr. Bill

 

[Chris P. D.]

Thanks for the help. Chris

 

[Uncle Pug]

if you have a blow out in the O-ring going to your primary first stage? It's not like you can isolate it from your primary or can you?

... you don't isolate (that term refers to isolating double tanks) but rather shut down the post with the blown first stage o-ring.

An H valve uses one side of a doubles manifold but instead of a crossover another post is installed in the crossover port.

You then have two valve handles each of which controls it's own first stage.

(The crossover port is open to tank pressure and must have either an H-valve, crossover or plug in it.)

Here is a picture.

 

[Mo2vation]

... you don't isolate (that term refers to isolating double tanks) but rather shut down the post with the blown first stage o-ring.

An H valve uses one side of a doubles manifold but instead of a crossover another post is installed in the crossover port.

You then have two valve handles each of which controls it's own first stage.

(The crossover port is open to tank pressure and must have either an H-valve, crossover or plug in it.)

Here is a picture.

In the pic. If I shut down the black knob, only gas flow to the left side (facing the pic) of the valve is shut down, or is gas to both sides shut down?

Clearly closing the gray knob only closed the right side (facing the pic)

Thanks -

K

 

[Uncle Pug]

black knob shuts down only the main post (does not affect the crossover port.)

Gray knob shuts down only the post below it (does not affect the main post.)

 

[theskull]

And buy your second tank with the H-valve going off in the opposite direction. Then when you're ready to twin them up, all you need is the isolator manifold and a set of bands.

theskull

 

[Chris P. D.]

Okay now you guys are starting to confuse me. Let me make sure i have this correct. If i get an H-valve for one of my tanks, according to the picture above, if i was to shut down the black knob it would only shut down the air flow to that 1st stage regulator and continue to flow to your second first stage reg? So the black knob isn't the tank shut off knob but actually just to that reg?

 

[Uncle Pug]

That is correct... it only shuts off flow to that post... flow is still open to the cross-over port (always) and that is the port where the H-valve is installed (the one with the gray knob.)

Note: the knobs are not always different colors but in this illustration help us in talking about it.

In order to use an H-valve your tank must have one half of a manifold valve set. The main tank valve pictured is not an ordinary K-valve it is the right post valve of a manifold set. If you were using doubles you would use that one in the right tank and a mirror image one in the left tank. Where the H-valve is in the picture there would be a cross-over connecting both tanks so that they were essentially open to one another. This cross-over may or may not have a valve in it. If it does that is called and isolation manifold and when closed isolates the tanks from each other. When open it allows either first stage to access all of the gas in both tanks.

A manfold set with isolator is shown here.