Non-isolation yoke manifolds

[KD8NPB]

I'm just curious.

I'm looking to purchase a doublehose within the next year or so...The VDH Phoenix conversions are quite sexy pieces of equipment!

There's a guy nearby with 2 x J-valve LP72s for $50. They're out of hydro, but still have air in them. I'm going to take a peak and see if they're rusty at all. If they're in good condition, I'll pick them up. I was thinking of ditching the J-valves, in favor of a non-isolating manifold...I already dive with a BP+W and have a Hog 32 single + 38 double

There are the two types of these manifolds though : orifice on top, or orifice on bottom.

My question is, are the bottom-orifice top-knob non-isolating manifolds still comfortable with a doublehose?

In the mean time, I'm using a Conshelf 14 set. I imagine ~140 CF of gas to be quite nice for bottom time.

 

[herman]

I see 2 possible problems with what you have in mind.
First off, it is very likely that the BP will not allow proper placement of the DH reg. For optimal performance a DH reg must be located low on the back, ideally between the shoulder blades and as close as possible to your back, most BPs will not allow the cans of the reg to be placed low enough. When diving singles with a BP that has a STA, it moves the tank away from the back so a BP with a STA is not acceptable either. This is the reason Luis and Bryan spent so much time and effort to develop a BP just for DH regs.
For a DH reg, you will want the outlet of the manifold to be on the bottom, again, so the reg can be placed as low as possible. Many of the old 3 piece manifolds could be assembled such that the outlet was up or down and I have seen photos of some where the outlet was simply loosened and turned up....works Ok for single hose reg but it puts the J valve on the wrong side.
My best suggestion is to find an old BP that was intended to be used with DH regs (the thin ones, not the molded plastic ones that are 3/4 of an inches thick) and spend some time diving the DH with single 72s until you have some experience with them. I highly recommend you find someone in your area who routinely dives a DH reg (not someone who “dove them in the day&#8221 and spend some time with them learning the proper way to dive a DH reg. You can dive a DH improperly and it will work but odds are you will not like it. To get the best out of them, you really have to dive them correctly and a large part of that is proper placement.

 

[elan]

It will not work well with the regular plate. The reg will breath really hard.

 

[Ed Palma]

One of these days, I'm going to put my 72s back together and use a cheater bar and try it out with the aluminum plate I cut out for single tank use before:

Of course, when the VDH backplate came out, my modified plate got pushed to the side.

(Now THAT's sexy!)

Maybe its time to revive my Al BP for doubles!

 

[Sam Miller III]

DOC ED,
The VDH back plate is no new! It is a some what warmed up version and a very close copy of the 1950s single tank SeaQuest Back Plate. It was developed and marketed in the double hose era for double hose regulators...

sdm

 

[herman]

Ed's photos are a good example of why a modern BP will not work (well). Notice the cutout at the top of the VDH one that allows the cans to be placed a lot lower on the BP, Eds modern plate has been modified with a cutout, normally it would be straight across. Also note the lack of the ridge up the center of the VDH BP (and the fairly pronounced on the modern BP). That ridge will lift the tank and your reg off your back by an inch or so. That does not sound like much but that will have a considerable effect on the performance of a DH reg. By lifting it 1 inch off your back, you will increase the cracking pressure of a reg by about 1 inch of water column (which are the units a regs cracking pressure is measured in). Increasing the cracking pressure of a reg by 1 IWC may not sound like much but in reality it turns a great breathing reg into a dog, that little bit of difference in placement is very important when diving a DH reg. On the other hand, it has no effect at all.....well none that you could feel....on a single hose reg. The accumulative effects of raising the tank off your back and moving it high on your shoulder will make a great breathing DH reg breath like crap. The uneducated DH diver tends to blame the reg....and one of the reason you hear so many stories of how bad DH regs are (and to be fair, some are bad). In reality, a properly worn and tuned Royal AM or Phoenix with the modern parts can hold it's own with most mid to high end modern regs, even more so with the release of the new second stage.

 

[simonbeans]

I'm just curious.

I'm looking to purchase a doublehose within the next year or so...The VDH Phoenix conversions are quite sexy pieces of equipment!

There's a guy nearby with 2 x J-valve LP72s for $50. They're out of hydro, but still have air in them. I'm going to take a peak and see if they're rusty at all. If they're in good condition, I'll pick them up. I was thinking of ditching the J-valves, in favor of a non-isolating manifold...I already dive with a BP+W and have a Hog 32 single + 38 double

There are the two types of these manifolds though : orifice on top, or orifice on bottom.

My question is, are the bottom-orifice top-knob non-isolating manifolds still comfortable with a doublehose?

In the mean time, I'm using a Conshelf 14 set. I imagine ~140 CF of gas to be quite nice for bottom time.

Sorry, but everytime someone asks to put a DH on some BP+W (what ever that is) and is a Hog or DIR type this thought comes to mind:

(But I guess if they had them, they would have used them. Amazing how diving ever made it to the 21st century with just a reg, tank and harness)