Popping sensation in 109 and 250 style regulators

[Aloha Joe]

@stuartv mentioned experiencing this on his Halcyon regs so now I know it’s not just me or my particular reg. I’m wondering if anyone else experienced this?

I have a 109 that has a ‘popping’ sensation when the valve opens: it’s like a step change in air delivery when the poppet reaches a certain point. I ‘believe’ it did this with the original, non-balanced poppet. I bought a complete new set of BA parts (latest poppet and lever, etc.) and upgraded the reg. At first it wasn’t noticeable, but about halfway through the dive it stated to come back, albeit much more subtle than before the upgrade. I did not change the (clear) diaphragm and will try swapping with my 250 to see if that changes anything.

I should mention that I also tried gently inhaling on un-pressurized regs and still notice the popping only on the one upgraded 109. It’s much more pronounced that way but obviously the forces are really different.

If the problem persists across poppets, chambers, levers and springs, then I’m thinking it’s either the diaphragm or the "lever hole" in the air tube? The popping reminds me of pushing on the lid of a cookie can or altoid tin, where it starts to deflect quietly and evenly with pressure, then pops into a different position at some point. So maybe it’s the way the diaphragm collapses under pressure? Or, maybe an edge of the lever is getting hung up on a burr in the air tube?


Any thoughts or similar experiences?

 

[lexvil]

While not running any experiments on the idea, I think it’s probably a condition brought on by a mis match of the lever/poppet/ air tube.

 

[Aloha Joe]

You may be right. I thought I ordered a set that was known to work together, but here's a post about a similar issue using the newest 'curly foot' lever:

?? Scubapro 109/150 lever version

I understand that older Scubapro adjustable metal 2nds may not work correctly with the new poppets and older levers. Can someone explain the symptoms and cause of the problem. I have a number of these older metal 2nds and all seem to be working fine with their original levers. I picked up...

scubaboard.com

 

[Open Ocean Diver]

Venturi effect.

 

[Angelo Farina]

No, the problem is a small ridge or indent in the surface against which the lever feet work, inside what you call the "air tube".
That is usually called the "barrell".
You must carefully smooth flat that surface using a very thin grane file.
One of my oldest 109 also develeped that problem.
It is caused by many years of work of the old lever with feet having a sharp edge.
The new lever with curvy feet does not cause the indent/ridge to develop, as during its action it "rolls" over the brass surface, instead of just rotating on the sharp edge as the old lever was doing.

 

[buddhasummer]

No, the problem is a small ridge or indent in the surface against which the lever feet work, inside what you call the "air tube".
That is usually called the "barrell".
You must carefully smooth flat that surface using a very thin grane file.
One of my oldest 109 also develeped that problem.
It is caused by many years of work of the old lever with feet having a sharp edge.
The new lever with curvy feet does not cause the indent/ridge to develop, as during its action it "rolls" over the brass surface, instead of just rotating on the sharp edge as the old lever was doing.

FWIW I agree.

 

[Aloha Joe]

Thanks guys. It does make sense, since switching to curly foot seemed to have reduced but not eliminated it. It’s a tough spot to inspect and work on. But I’ll take a look after I get my other reg set up and running.

 

[buddhasummer]

On a 109/156 yes, very hard to get into both sides. On G250s I use a tiny diamond (?) file.

 

[stuartv]

I don't know how I missed seeing this thread before...

I am dubious that this problem is any of the stuff y'all have said. At least, on my Halcyon Halos...

The reason I am dubious is that, first, mine do not have very many hours on them.

And second, because after servicing them, the problem seems to go away and then gradually come back after not too long. If it was a ridge or something in the air barrel, it seems like the problem would not go away and then gradually come back.

And third, it's obviously not mismatched parts, as my Halos did it from not too long after new and only have original OEM parts.

Mine are at my shop right now for someone more knowledgeable than me to work on them. I think Halcyon is also supposed to have sent some new parts, too, but I don't know details on that.

Lastly, I have 2 Halos on my single tank reg set. They both do it. The one I use as my primary does it worse.

 

[buddhasummer]

Interestingly my new C370 exhibits same behaviour. I'm going to pull it apart.