Breaking in 2nd-stage 'seats' by leaving adjustment knobs fully closed for awhile ?

[scubafanatic]

I recently had a dozen Scubapro 109/156's serviced, and to break in the seats, all were shipped to me with 2nd stage knobs in the fully closed/cranked down position, and they remained in that position for about 5 days (as I was instructed to leave them in that position 'for a few days' to break in the seats, so I guessed a few days = 5 days, including the shipping days).

I tested 2 'seconds' so far, both are freelowing, one stops freeflowing if 2nd stage adjustment knob is at least 1/2 cranked down, the other won't stop even if fully cranked down (although I can almost stop the air leak).

I have not yet tested the rest of the 2nd-stages (as if 2 randomly chose units, and are both leaking, it's likely some/all the rest will have the same issue.)

I know I can do orifice adjustments (I'm awaiting a tools order from Scubatools.com to arrive next week) although I've never done orifice adjustments before.

Did we follow an acceptable practice in breaking in all my seats, or have we damaged/destroyed the seats, requiring replacement ?

Or is it a simple orifice adjustment and I'm probably OK ?

Thanks in advance,

Karl

 

[lemke]

What did the shop say that serviced and sent them to you?

 

[redacted]

It is almost surely a simple orifice adjustment. The tool just makes it a bit faster. It would probably be good (and almost as easy) to do it without the tool so you will be able to see the difference that tool makes.

 

[scubafanatic]

What did the shop say that serviced and sent them to you?

I only heard about this as maybe being a possible 'issue' this afternoon (directly from the 'servicer' = couv) so I haven't gotten a response from him yet. He suggested I start posting such questions here in the DIY section for wider readership and helpful responses, so I started a new thread here and tossed it into the SB pool to see if the usual helpful DIY suspects would respond.

---------- Post added August 3rd, 2014 at 06:46 PM ----------

It is almost surely a simple orifice adjustment. The tool just makes it a bit faster. It would probably be good (and almost as easy) to do it without the tool so you will be able to see the difference that tool makes.

Hi awap, OK, I feel a bit better now. For the time being, we'll assume it's just that simple adjustment that's needed. I've got tools from Scubatools.com on the way (shipped out to me late last week) and assorted reg components (LP hoses/ SPG's) arriving from Scubatoys tomorrow. Hopefully starting next weekend I can test/adjust the 2 complete reg sets I've already assembled, and then get started on assembling two more reg sets once this weeks supplies arrive.

Thanks again, Karl

 

[halocline]

Did we follow an acceptable practice in breaking in all my seats, or have we damaged/destroyed the seats, requiring replacement ?

Karl

I'm sure the seats are fine but I don't understand why couv would ship them that way. You would want any 'break in' the seats to happen before doing the final orifice adjustment, not after. I would definitely back off the adjustment knob all the way out, and leave it there until you're ready to adjust the orifice. It's pretty common to need to adjust those a bit as the seat wears anyway, especially if they're tuned for maximum performance.

If you only got 2nd stages from couv, it's also possible that he adjusted them with a first stage that has lower IP than yours. You really need to do the final orifice adjustment with the 1st stage that you're planning on using, and if it's a piston 1st, with a full tank. Even the balanced MK5/10 drops IP several PSI throughout the supply range.

 

[NotSure]

You say that the regulators were Scubapro 109/156's. The 109 and 156 use a different poppet and spring with the 156 having a much lighter spring. This means that the 156 probably exerts less force on the seat with the knob cranked all of the way in then the 109 does with the knob all of the way out. You need to check your IP to make sure it is within acceptable limits as previously suggested.

 

[scubafanatic]

I'm sure the seats are fine but I don't understand why couv would ship them that way. You would want any 'break in' the seats to happen before doing the final orifice adjustment, not after. I would definitely back off the adjustment knob all the way out, and leave it there until you're ready to adjust the orifice. It's pretty common to need to adjust those a bit as the seat wears anyway, especially if they're tuned for maximum performance.

If you only got 2nd stages from couv, it's also possible that he adjusted them with a first stage that has lower IP than yours. You really need to do the final orifice adjustment with the 1st stage that you're planning on using, and if it's a piston 1st, with a full tank. Even the balanced MK5/10 drops IP several PSI throughout the supply range.

I was told that all my 109/156 2nds were tuned to a SP 1st stage running an IP @ 135 psi, which is also exactly where couv set all my newly serviced MK 5s, per my request. The break in process involved the sheer number of stages I shipped to him. ( 12 2nds, 6 1sts ) There wasn't time/air enough for him to break everything in, so I was to do my own break in of all the stages, I was directed to assemble reg sets and, once assembled, leave each reg set pressurized overnite to complete 'break in'. I never made it to that point as I aborted the process once my 1st set was found to be free flowing. All 2nds were shipped to me with 2nd stage knobs fully cranked in, to help break in the seats, after a total of a 'few' days elapsed I was instructed to fully open the 2nd stage adjustment knobs, so all 2nd stages have been sitting in the fully open state after being in a fully closed state for 5 days.

So fortunately all 2nds have remained in the fully opened state ever since the 5 day interval elapsed, awaiting tools to arrive.

---------- Post added August 3rd, 2014 at 10:57 PM ----------

You say that the regulators were Scubapro 109/156's. The 109 and 156 use a different poppet and spring with the 156 having a much lighter spring. This means that the 156 probably exerts less force on the seat with the knob cranked all of the way in then the 109 does with the knob all of the way out. You need to check your IP to make sure it is within acceptable limits as previously suggested.

It was an assortment of both 109's and 156's (mostly 109's) ALL units were fully upgraded/modernized to current Balanced Adjustable 156 'standard' (using a bunch of parts sourced from VDH and E-bay). I have not as of yet confirmed the IP on the MK 5 1st's, I do have an IP gauge, but was more focused on the 1st's initially. Next weekend I may just attach an odd Aqualung 2nd stage 'spare' onto a MK 5 and confirm the IP is in range. I appreciate the suggestions, keep 'em coming!

Thanks, Karl

 

[rsingler]

You'll find when you start adjusting the orifice yourself, that the difference between seal and freeflow is about 1/24th of a turn (a half hour on the clock). Translating that into distance moved with Scubapro threads, we're talking about .05mm depression of the seat to make a seal at 135 psi.

If your servicer ships your reg to you with a new (flat) seat that is very lightly sealed (low cracking effort), it will almost surely freeflow as the seat takes a set and the ring depression from the orifice becomes permanent. That is why it is a very common practice to "de-tune" the regulator by adding 1/12 turn after reaching the desired seal. That translates into a cracking effort that is about 0.2" higher than desired, with it dropping as the seat takes a set.

Once the orifice is set, adding spring pressure by screwing in the adjustment knob is a VERY subtle change on the poppet. Theoretically, the poppet shouldn't move at all, because it is already resting against the lugs of the lever. In practice, it shifts slightly. What changes is the force required to OPEN the seal.

So, there's nothing wrong with couv's practice. And your freeflow is no big deal. In fact, Sherwood recommends a freeflow when its knob is fully out, and only seals with it in 1/2 turn. Your reg that won't seal at all just needs a little further adjustment.

Don't wait for your tools. Just take a screwdriver (or a shaved clothespin if you don't want to scratch the inside of the barrel) and screw in the orifice 1/24th turn with the purge button depressed. Reconnect your hose and pressurize. If the freeflow stopped, check your cracking effort in the sink. See if the reg hisses with the diaphragm submerged 1 to 1 1/2 inches. Boom, you're done.

If not, screw in/out 1/24th turn at a time until you get your freeflow fixed and your cracking effort where you want it.
Yes, the magnehelic and inline adjustment tools will make what I've just described a three minute effort instead of a half hour, but the end result is the same.

Cheers!

 

[Zung]

If you have the blue Trident aftermarket seats, they're very tough, and break-in is optional.

I scored a couple of transparent G250's in March, couldn't find anything wrong inside except the original seats were deeply marked, do I replaced them with the blue seats, did the stop flow + 1 hour trick, and they both cracked "naturally" at 22mm/.9" as measured with my $2 manometer.

They went in the closet until July when I tested them again, no change, still 22mm/.9". They were stored with the knob fully out.

With the 109/156, there's no need to go for the lowest possible cracking pressure. Anything lower than 1" and they'll free flow (slightly) in a head down position because of their geometry.

 

[halocline]

Once the orifice is set, adding spring pressure by screwing in the adjustment knob is a VERY subtle change on the poppet. Theoretically, the poppet shouldn't move at all, because it is already resting against the lugs of the lever. In practice, it shifts slightly. What changes is the force required to OPEN the seal.

Not exactly, I believe that setting the orifice pushes the poppet back a bit, this is why the lever drops a small amount. So the spring pressure is actually pushing the soft seat against the orifice edge. The poppet movement is restricted by the lever lugs only when it is at it's highest point possible and the lugs are 'flat' against the side of the holes in the barrel.