Double manifold repair?

[OldNSalty]

I noticed I have a leak on the right post coming from under the knob. I have never taken one of these apart but I am guessing it is an o-ring? If I shut the isolator valve and drain the right tank should I be able to remove the knob and replace the o-ring or is this a case of having to take the entire manifold off to work on it?

 

[tbone1004]

if it is only leaking when the valve is open, there is no need to drain the tank. Remove knob, leave the seat in place, replace the o-ring and reassemble. O-ring #17 in that picture. Can't remember what size it is. If it is not a thermo, it is still the same component, most valves are basically the same

 

[OldNSalty]

Awesome. Thanks! Yes, it only leaks when I open it so I'll replace it tonight. Appreciate the help!

 

[Sevenrider860]

For Thermo it is a 010. To get to it you need to remove the bonnet nut. I will always replace the copper crush washer and retorque if I remove the bonnet nut.

 

[2airishuman]

You have to be careful not to turn the stem when you remove the bonnet nut.

There are two designs in widespread use. The thermo valves use a copper crush ring inside the threads. That design is a carryover from industrial gas valves, and has the benefit (for applications involving corrosive or high-purity gases) that the threads are not exposed to the gas. DGX and Dive Rite manifolds use an O-ring to seal the bonnet, which is outside the threads, so that the threads aren't exposed to salt water.

As for your leak, replacing the o-ring may clear it up. There's also a teflon washer that may need replacement, or the valve stem may be scratched. All of these are available as service parts from multiple sources. It is helpful to use a very light coating of a suitable lubricant during reassembly. Like most divers, I use an oxygen safe lubricant (Tribolube).

 

[Caveeagle]

For Thermo it is a 010. To get to it you need to remove the bonnet nut. I will always replace the copper crush washer and retorque if I remove the bonnet nut.

I would assume a D90 on that o-ring holding high pressure.

Anyone want to confirm that?

 

[Sevenrider860]

90-duro is what I use.

 

[Caveeagle]

90-duro is what I use.

I think that's an important point. Just slapping an 010 in there from the save a dive kit might not be the safest fix for a leaking manifold. I think it's also worth pointing out that the other two valves probably are due for attention, if this one has give up on life.

 

[2airishuman]

I think it's also worth pointing out that the other two valves probably are due for attention, if this one has give up on life.

The whole manifold should be disassembled, cleaned, and serviced from time to time. It is not uncommon to do that at hydro time. On my manifolds I do that sort of work outside of the dive season.

 

[halocline]

If you're using this manifold for tech dives I would rebuild it soon. There is a design flaw in these in that the isolator seat only really protects one tank; the other could leak out the isolator valve stem just like the leak you have. I remember being really surprised about this when I first learned it.