Scubapro balanced adjustable second stage freeflowing

[MarkH]

Just found this for some Scubapro manuals:Index of /Public/Scubapro
All relevant 1st stages state 125-145 psi IP.

 

[lexvil]

First, IP, if you are between 130 and 150 psi you’re good so long as it locks up in that range.
Second the lever height look good enough for you to screw the orifice in to stop the flow, if you have or can get the newer longer balance chamber that should help overall but unlikely to have anything to do with this issue.

Third there have been some massive improvements in regulators in the 40+ years since these were at the top of the game…

 

[axxel57]

Okay, an upgraded SP109. With the old Membrane cover it could be easily from the early 70ties.
So the original components like the threads in the barrel could be worn and have some little play from earlier cleanings.
And yes, it's not a matter of the IP in this case.
Unfortunately one cannot see the marks on the LP Seat really, but for me ( I could be wrong) the marks on the left side of the seat seem to be a bit deeper than on the other side.
That would correspondent with my impression that the spring is slightly bend on the right side (pic) and not completely straight.
I still think that a new spring and maybe a new orifice can improve the performance significally ( of course you need then a new LP Seat too).
Probably the problem is caused by a mix of different factors. These 50+ years old stages can be difficult to adjust to a reasonable performance and often it is neccessary to change almost all mechanical components.
And even then some worn out holes for the lever feets can make you crazy if you don't realize them.
Anyway, try first a new spring.....

 

[MarkH]

First, IP, if you are between 130 and 150 psi you’re good so long as it locks up in that range.
Second the lever height look good enough for you to screw the orifice in to stop the flow, if you have or can get the newer longer balance chamber that should help overall but unlikely to have anything to do with this issue.

Third there have been some massive improvements in regulators in the 40+ years since these were at the top of the game…

Even with the orifice screwed in all the way, it still freeflows unless I screw in the adjusting knob almost all the way in. I'll keep trying things later today after work. The reason I wanted to experiment with switching out my Conshelf 14 second stage with this one is because I assume it would breathe slightly better. Recently I bought a used dive computer and it came with 2 full sets of free dive gear, including 2 Oceanic FDX10 regulators. Unfortunately the second stages are plastic and when I picked them up, the diaphragm covers crumbled into little pieces in my hands. I bought a service kit and a new cover and rebuilt one of them and tried it out and it seems to breathe noticeable better than my Conshelf 14 (which have been my regular regs over the last 25 years). Sometimes when swimming semi-hard at depths below 80 or 100', I felt a bit of lightheadedness from slightly over-breathing the reg I assume. With the Oceanic I didn't feel any of that. It's a balanced adjustable second stage so it can be tuned on the fly to almost slightly freeflow. I was hoping the Scubapro Balanced Adjustable could be tuned to have less breathing resistance and cracking pressure than the unadjustable Conshelf. Plus I have a thing for metal second stages (except for the Poseidon Cyclon 300, which had too high of a cracking pressure for me to feel like it breathed naturally and the soft aluminum housing was always getting bent or crushed slightly out-of-round).

 

[MarkH]

Okay, an upgraded SP109. With the old Membrane cover it could be easily from the early 70ties.
So the original components like the threads in the barrel could be worn and have some little play from earlier cleanings.

Ah, that's what I was wondering, if this was an actual Balanced Adjustable housing or an upgraded 109. The metal diaphragm cover says "Balanced Adjustable" on it, but I assume that could have been part of the conversion kit. Maybe I'll try adding the components from the upgrade kit to my other 109 and see if there's a difference.

 

[lexvil]

Even with the orifice screwed in all the way, it still freeflows unless I screw in the adjusting knob almost all the way in. I'll keep trying things later today after work. The reason I wanted to experiment with switching out my Conshelf 14 second stage with this one is because I assume it would breathe slightly better. Recently I bought a used dive computer and it came with 2 full sets of free dive gear, including 2 Oceanic FDX10 regulators. Unfortunately the second stages are plastic and when I picked them up, the diaphragm covers crumbled into little pieces in my hands. I bought a service kit and a new cover and rebuilt one of them and tried it out and it seems to breathe noticeable better than my Conshelf 14 (which have been my regular regs over the last 25 years). Sometimes when swimming semi-hard at depths below 80 or 100', I felt a bit of lightheadedness from slightly over-breathing the reg I assume. With the Oceanic I didn't feel any of that. It's a balanced adjustable second stage so it can be tuned on the fly to almost slightly freeflow. I was hoping the Scubapro Balanced Adjustable could be tuned to have less breathing resistance and cracking pressure than the unadjustable Conshelf. Plus I have a thing for metal second stages (except for the Poseidon Cyclon 300, which had too high of a cracking pressure for me to feel like it breathed naturally and the soft aluminum housing was always getting bent or crushed slightly out-of-round).

Go borrow a G260, S600/620, an Atomic (any) and when your head clears from a reliable supply of oxygen you’ll these “metal” seconds are just curiosities from a time when we didn’t possess the technology for doing things right.

These old regs can be a great distraction and time killer but there are far better options for breathing underwater.

 

[scrane]

The old metal ScubaPro's should work just fine as long as they're not damaged. They worked 30 years ago and nothing's really changed.
Again, the variables are: IP, orifice condition and position, seat condition and position, and spring + balance chamber counterpressure.
Did you try it out before the rebuild? Did it work OK? Who knows what the previous owner did or what parts he might have used.
Does it seem the balance chamber is bottoming out when, as you say, the adjuster is screwed all the way in? Weak spring?
Are all the parts present, correct and assembled correctly? Take it back to start. Look REALLY carefully at the orifice. Run your thumbnail around the sharp edge and feel for roughness. Is the o-ring OK?
If its not the orifice I'd suspect its the spring. Check all the ballpoint pens in your house for a temporary substitute or shim the one you have to increase tension.
There's not a lot of variables. You'll figure it out!

 

[MarkH]

The old metal ScubaPro's should work just fine as long as they're not damaged. They worked 30 years ago and nothing's really changed.
Again, the variables are: IP, orifice condition and position, seat condition and position, and spring + balance chamber counterpressure.
Did you try it out before the rebuild? Did it work OK? Who knows what the previous owner did or what parts he might have used.
Does it seem the balance chamber is bottoming out when, as you say, the adjuster is screwed all the way in? Weak spring?
Are all the parts present, correct and assembled correctly? Take it back to start. Look REALLY carefully at the orifice. Run your thumbnail around the sharp edge and feel for roughness. Is the o-ring OK?
If its not the orifice I'd suspect its the spring. Check all the ballpoint pens in your house for a temporary substitute or shim the one you have to increase tension.
There's not a lot of variables. You'll figure it out!

Unfortunately I didn't hook the reg up to a tank before disassembly. I might try it with the old poppet re-installed. Looking at the orifice again up close with a lens, there seems to be a small brass-looking area at one part of the knife edge. I assume these are chromed bronze. So it might be the orifice. I'll try the one from my 109, which is a known good one, but I'd expect tiny damage to the orifice or seat to result in a tiny hiss, not a louder freeflow. The culprit does seem to me to be spring related, or something not providing enough force to counteract the IP, but the original owner (my neighbor) used it fine and then put it away for over 10 years so the spring was correct at least back then and it doesn't look damaged now.

 

[MarkH]

So I may have made some diagnostic progress. I swapped out the orifice from the known good one from my 109. Still the same. Still free flowing. Then I decided to check the IP of the 1st stage that this Balanced Adjustable came from. The 1st stage is a Conshelf SE2. The IP was only 125 psi. I'm pretty sure that it should be the same as my Conshelf 14 = 140 psi. This means that that IP was deliberately lowered significantly. I assume it was a cold water anti freezing thing. This lowered IP makes me think that the Balanced Adjustable might have been assembled with a weaker spring than the original. I put the Balanced Adjustable on the SE2 1st stage that it came with and I was able to sort-of set it up to breathe with the adjustment knob turned half-way in. I should probably give up on this reg, but I'm stubborn so I'll probably try and order a proper spring somewhere and try that.

 

[Nemrod]

The 109 BA is a G250/G260 without a variable Venturi and with the too small 26mm exhaust valve and restrictive exhaust tee. Set up and adjustment are essentially the same as a G250 otherwise.

Performance wise, the 109 is not equal to a G250/G260 because it has a less effective Venturi and the smaller 26mm exhaust valve and tee and a few other things. It should be entirely adequate for recreational scuba diving.

The most likely culprit is a bad orifice or that the new seat has been cut by not retracting the poppet when turning the orifice. Or the diaphragm and/or cover have become hard and are pressing the lever (does the regulator free flow with the diaphragm removed?). Or your parts stack up is incorrect or there is a compatibility issue (lever and poppet).