"Small" leak on 300 Bar DIN valve

[JohnN]

I'm testing a recently purchased used DIN regulator (HOG D1) to see how well it holds its IP, and when it is fully seated into a 300 Bar valve, I hear a small leak through a bleed hole in the body of the valve. I can't easily submerge the tank/1st stage, but it sounds like one of those "tiny bubbles, no troubles" types of leak

I've replaced the "O" ring and can still hear that slight hiss. . .

Putting my finger over the hole stops the hiss and I don't notice any particular pressure release when my finger is removed.

I don't recall ever seeing something like this on 240 Bar valves, and my other tanks (with 300 Bar valves) are getting a hydro so I can't compare to them.

So two questions:

1. Should I keep chasing that leak (and replacing that O-ring) to hope to find a magical combination?
   
   
2. Why is that bleed hole there in the first place

 

[2airishuman]

I'm testing a recently purchased used DIN regulator (HOG D1) to see how well it holds its IP, and when it is fully seated into a 300 Bar valve, I hear a small leak through a bleed hole in the body of the valve. I can't easily submerge the tank/1st stage, but it sounds like one of those "tiny bubbles, no troubles" types of leak

I've replaced the "O" ring and can still hear that slight hiss. . .

Putting my finger over the hole stops the hiss and I don't notice any particular pressure release when my finger is removed.

I don't recall ever seeing something like this on 240 Bar valves, and my other tanks (with 300 Bar valves) are getting a hydro so I can't compare to them.

So two questions:

1. Should I keep chasing that leak (and replacing that O-ring) to hope to find a magical combination

I would. You may find that there is dirt or other contamination on the sealing surface for the O-ring, possibly on either the valve or the regulator. Or there may be a nick in the seating surface. Or it may be that the threads don't seat all the way.

1. Why is that bleed hole there in the first place

They release, in a more or less controlled and predictable manner, the high-pressure gas that is trapped in the event that the valve is opened (or leaks) while a port plug is installed. When this happens, the O-ring will follow the port plug up the threads. Absent a bleed hole, it will vent through the threads at some unpredictable point, and could in theory discharge the port plug under pressure.

 

[Caveeagle]

Swap out the DIN seal o-ring. It would be nice to just move the reg to a different tank, or put a different reg on that valve to isolate if the problem is more-or-less with the tank/valve or the reg.

I have several 200bar and 300 bar DIN valves. Some have the hole, and some don't.

The hole makes a leaking DIN o-ring obvious. Without the hole, the bubbles would escape from behind the DIN reg wheel and it would be hard to tell if you had a bad DIN o-ring seal, or a leak coming from the reg first stage body.

 

[PfcAJ]

I hate those little bleed holes.

 

[tbone1004]

I hate those little bleed holes.

they're basically required if you have the metal valve plugs without a bleed built in though....

@JohnN you should have them on your 200bar convertible valves, but it's likely something on the seating face in the valve

 

[PfcAJ]

they're basically required if you have the metal valve plugs without a bleed built in though....

@JohnN you should have them on your 200bar convertible valves, but it's likely something on the seating face in the valve

Nah back off the plug enough with a BFW and itl'l leak. Promise.

 

[tbone1004]

Nah back off the plug enough with a BFW and itl'l leak. Promise.

super super slowly though and it still puts a lot of back pressure as the gas has to escape through the threads. I guess it depends on the tolerances of the threads on the valve and plug, but it's going to mostly seal. I'd much rather have that little hole to allow pressure to bleed off. Just means you have to care of the o-ring and seating face...

 

[RainPilot]

I believe the bleed is a safety factor for someone putting a 5 thread 200 bar DIN on a 7 thread 300 bar valve. The idea is that the excess will bleed out there since the reg threads haven't covered it, preventing a blown first stage.

 

[PfcAJ]

super super slowly though and it still puts a lot of back pressure as the gas has to escape through the threads. I guess it depends on the tolerances of the threads on the valve and plug, but it's going to mostly seal. I'd much rather have that little hole to allow pressure to bleed off. Just means you have to care of the o-ring and seating face...

I do it all the time man. It's not slow. Takes a turn of the plug and it's good to go.

 

[Trace Malinowski]

The O-ring on the back of the DIN screw is the next place I look once the front O-ring is replaced.