Re-using old balance chambers

[Six2Life]

I have two SP balanced 2nd stages that currently have the old metal stemmed blue poppet installed that needs replacing. One is a G250 that I know has seen very little total use. (maybe 10 dives) The other is a BA that I am unsure of the history on but looks to be well used and maybe not rinsed extremely well.

Will there likely be any problems with re-using the balance chambers with new s-wing poppets? I'm thinking the G250 should be ok but maybe not the BA. Didn't SP include a new balance chamber in the service kits when the s-wing was introduced due to wear issues from the metal stem in the balance chamber? I'm just trying to decide if I should replace the poppets now or wait until I scare up a couple of new balance chambers.

 

[Zung]

You can test it. DA Aquamaster described a method where you hold the poppet in one hand and use a finger to block the hole in the seat; and with the other hand you push the balance chamber in and out. If you feel a resistance, it means the rings are sealing and you should be OK.

Theoretically, the older stem used a single 2.5 x 1 mm o-ring that MAY wear the chamber a bit more than the current double 2.2 x 1 mm o-rings. But I've re-use a couple of the old chambers with the current poppets and dived them without any dire consequence that I know of.

Edit: DA's piece is here.

 

[Couv]

The older balance chambers can still be used if they pass the test Brother Zung mentioned. The difference is that the new balance chamber is a bit longer to accommodate the 2 o-ring stem configuration on the S-wing poppet. Two o-rings are used-one as a wiper, one to actually seal; but they work together to act as a small lubricant reservoir.

Having said that, the single seal poppet/chamber combination was used for decades with no issues.

Couv

 

[Zung]

... the new balance chamber is a bit longer to accommodate the 2 o-ring stem configuration on the S-wing poppet...

Very good point, Bro.
I'm pretty sure I only have a couple of the long chambers out of a dozen BA's/G250's, and most of my G250's have the dual o-rings poppets from stock.
I may have fitted the short chambers to the dual o-ring poppets in the pass; I'll have to take my gears apart to check. Until then, can any guru confirm the (in-) compatibility of this combination?

 

[redacted]

I do not believe there is any incompatibility. I went through my stash and found 2 different "new" style balance chambers that came in kits with the S-wing poppet. One is much longer as couv pictured. The other is a white balance chamber that is less than 1mm longer and that difference is accounted for in a taper to facilitate the installation of the poppet.

 

[Couv]

Yeah, I think I have 1 or 2 s-wing poppets matched with the short balance chamber and no problems. Remember, the o-ring that goes deepest into the chamber is the sealing o-ring and the other is a wiper. The old blue poppets only had one o-ring in the chamber.

 

[Zung]

Thanks to both of you, you're truely Great Masters. Saves me a lot of work taking my stuff apart.
Here's the "match":

 

[Six2Life]

Short balance chamber with s-wing poppet

I recently received this info on the balance chamber compatability issue. It is right along the lines of what awap mentioned:


"The photos below are a 109 cutaway air barrel that can actually be adjusted with full intermediate pressure.
I installed a c-clip through the air barrel to control the maximum retraction of the adjusting knob. Photo
#1 & #2 show the air barrel adjusted with air on and is leak tight. Look closely at the poppet stem where it
enters the balanced chamber. There is no o’ring visible. In photo #3, I removed the c-clip and retracted the
adjusting knob 2 full turns and the o’ring is now visible. In photo #4 the knob is positioned at 1 1/2 turns out
and the beginning of the o’ring groove is just barely visible. In my opinion, both of the stem o’rings are engaged
in the balance chamber with the air barrel in adjustment. I hope this sheds new light on the balance chamber
length issue. I would not hesitate to dive this set up. A longer balance chamber will not seal any better than this one."