Older OMS Manifold Manual

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rob.mwpropane

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Good day all. I searched here and all over the internets for a manual. I'm rebuilding this as I kept getting leaks. I can't tell if these allen heads are reverse threads or not, maybe they have loctite on them, and maybe it could be some salt in there? You can see the outer o rings were really shot.

I'm just asking for some guidance before I move forward so I don't bust anything. Any thoughts?

Also, I might just say the hell with it and replace the outer o rings and call it a day. I don't think the inner parts were leaking at all and I know the outer rings are just regular din o rings.
 

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Anybody? I mean, I can probably figure it out unless it needs something special when putting back together (like loctite).
 
Ok, so replying to my own thread in case anyone ever searches. I was able to source a rebuild kit from John @ North East Scuba Supply (someone on here pointed me in the right direction).

The allen threads inside the isolation the isolation manifold are reverse threads. No one anywhere knew for sure if they were or not. Man they were really in there. Cold ultrasonic, then hot, then cold again with 40/60 vinegar / water and they finally cracked loose in a vice with a hammer. A little this way and then that way.

No loctite residue, so I didn't use any putting it back together.

John's kit came with everything I needed. I also got new burst disks because why not.

Plus side is the valves glide super easy in either direction. They weren't hard before, but there's definitely a difference. I can see why these manifolds aren't as nice as the newer valves with the o rings in the barrel. As you can see in the 1st picture up top a lot easier to gum up the o rings sealing on the face than the newer style.

Another thing is my manifold didn't have any copper crush washers in it. I'm not really sure if they're needed but they have them now.

20220326_121937.jpg
 
I have a few of these manifolds
I don't really mind then to much,
The difference is the bands need to be accurate...

I use PVC spacers on the threaded rod to keep the tanks parallel. Custom made for the specific tanks.
Lay tanks down,
tight up manifold.
Cut and fit PVC pipe till its perfect,
Assemble, now there is no strain on the manifold...
 
Yeah, idk.. this was on my 1st set of doubles I bought and I really just didn't know and different. They do not have any spacer but the tanks (with the manifold still tight) unscrewed fairly easily out of the manifold with the bands just barely loosened. Nothing looks like it's been strained or was.

The bands are 3", not sure by who.
 
So this is my home made SS steel 72 bands
And I make custom spacers to match the specific tanks.
I have found the threads not to be totally parallel to the outside of the tanks,
So it can be a 1/8inch narrower at the bottom band. And that's to much stress on the manifold for me...
Its the machinist /fabricator in me I guess..

I don't think spacers are very common,
At least from what I have seen.

20220326_182550.jpg
 
So this is my home made SS steel 72 bands
And I make custom spacers to match the specific tanks.
I have found the threads not to be totally parallel to the outside of the tanks,
So it can be a 1/8inch narrower at the bottom band. And that's to much stress on the manifold for me...
Its the machinist in me I guess..
View attachment 714519

Do the spacers end up being the same width? I would imagine so.. I mean I'll throw a set in there.. anything to help stop them from moving / leaking.
 
Depends on the tanks,

I mount the valves,
Lay the tanks on a flat work bench,
Then install the cross bar,
Let the tanks lay naturally with the cross bar tight,
You kinda need to know where the lower tank band will be,
Measure with a set of calipers between the tanks,
Cut a PC of 1inch PVC pipe that size so it just fits
(I use a lathe to square up the ends,)
Snug up the lower band,
Now you can then make the top spacer because the manifold has the spacing set,
Really the lower spacer is the most important.

I generally find the bottom spacer is smaller than the top,,,

If you break up the set, make sure you mark the valves to the tanks, so your not messing around to get it assembled
 
Those ratty orings says to me the the cross bar was loose and had gap for the oring to extrude through,,,
 
Those ratty orings says to me the the cross bar was loose and had gap for the oring to extrude through,,,

It worked fine and then one day it leaked. I had pumped to 3600 and when I got to the boat it was down to 2000.. thankfully shallow dive. I tried tightening and it did stop, but it came back. That's when I decided to rebuild them.

The right post wasn't leaking, but the o ring was pretty messed up.

I will try some PVC and see how that looks / feels. Thanks for all the tips.
 
https://www.shearwater.com/products/teric/

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