Old ScubaPro R109 2nd stage

[halocline]

The unbalanced poppet is for the G200 and usually is not very hard to find. I see them on ebay for about $10 fairly frequently. The advantage of leaving them unbalanced is that subsequent rebuilds involve a few standard o-rings and a standard puck seat at a total cost of a few pennies. I do find that my balanced ones tend to be more stable than the unbalanced, and they do last longer between rebuilds because there's less pressure on the seat during storage. (You can store them in a way that takes pressure off the seat) Overall ease of breathing is very close between the two. Quite honestly, I've ended up deciding which ones to convert to balanced based on which poppet I happen to have lying around. The toughest part to find is the G250 spring; I usually get that one at a dealer.

 

[Zung]

awap:
Have you been able to use the old spring with the newer duro poppet?

Slightly off-topic:
There's a single o-ring poppet in one of my older G250's; any pro's & con's when compared to the current 2 o-rings ones?

 

[Zung]

If all else fail, you can try DA's secret receipe here

 

[redacted]

awap:
Have you been able to use the old spring with the newer duro poppet?

Slightly off-topic:
There's a single o-ring poppet in one of my older G250's; any pro's & con's when compared to the current 2 o-rings ones?

The spring is the same with the duro poppet.

The single o-ring 1-piece plastic poppet was around for the first year or so and then they went to the double o-ring S-wing poppet. Besides the addition of another o-ring to protect the inner o-ring that makes the balance chamber seal. the contact surfaces between the poppet and the wall of the barrel is changed a bit. Probably a little less friction. But I doubt if the difference is even discernible by a diver. I'd use it until it becomes a problem.

 

[Packhorse]

The toughest part to find is the G250 spring; I usually get that one at a dealer.

Its the same as a R190 spring ( which surprised me)

 

[Texfrazer]

Its the same as a R190 spring ( which surprised me)

Really? I thought that the unbalanced R190 spring was a lot stiffer (for lack of the appropriate spring terminology) than the balanced springs, ala G250.

 

[halocline]

Its the same as a R190 spring ( which surprised me)

I've heard that, so I just checked and it is the same part number. Thanks for reminding me. That makes it a little easier to find at SP dealers.

Tex, I bet you're thinking of the difference between the G250 and 109 spring, not 190. The 190 is also an unbalanced reg, but it's not a barrel poppet design, so the spring is compressed much more tightly. That's why the balanced barrel poppet spring works in it.

 

[Texfrazer]

Tex, I bet you're thinking of the difference between the G250 and 109 spring, not 190. The 190 is also an unbalanced reg, but it's not a barrel poppet design, so the spring is compressed much more tightly. That's why the balanced barrel poppet spring works in it.

Doh! That's what I get for not verifying! Thanks!

Also, that's some good info to know!

 

[Packhorse]

Yes, the 109 spring is a different beast,

This surprises me as the 190 has the spring doing a different job in a different place to a G250/156 ( well in a different place at least).

 

[redacted]

Really? I thought that the unbalanced R190 spring was a lot stiffer (for lack of the appropriate spring terminology) than the balanced springs, ala G250.

It is the same spring and it is a lot stiffer. With the 190 design which uses the same orifice as the G250 (and most SP 2nds) that spring has to hold back all the downstream force of the IP while it only holds back about 50% of the force in a balanced design. This is accomplished by compressing the spring quite a bit more in the 190 than in the 250. Unbalanced SP barrel poppet designs (109, G200, M-50, Polar) use a noticeably heavier (and longer) spring but does not compress it as much as is done in the 190.