Zeagle ZX 2nd stage question

[cdharris]

My Zeagle Flathead VI has a slight freeflow problem, and I'm interested in getting educated as to what might be up with it. The 2nd stage is balanced with a venturi switch and breathing resistance knob (BRK).

It was serviced by a very reputable shop late last year and worked fine for a few months of diving. Even with the knob set to minimum resistance, it breathed fine and did not free flow (and yes, I know how to use the venturi assist).

Then late this summer it began to have a slight free flow when the BKR was set to minimum resistance and I took a full, rapid breath. Now, I have to screw up the resistance more than one full rotation to stop the free flow and the venturi position doesn't really make any difference. When the BRK is turned in, say half a turn, it only free flows after a full breath and only very lightly. If unscrewed all the way, it free flows lightly all on its own. And yes, the IP is rock solid -- instantly -- at 135.

Interestingly, it also does not free flow at all until after I take my first breath. I can even put an IP gauge on it, open and then close the tank valve, and the IP is solid until I take a breath. Then it free flows continuously and the IP slowly falls until my SPG reads zero, but the IP is at about 100. Then it stops freeflowing.

Now what makes this especially interesting to me is that I went three years without servicing it the last time, and it was used and abused in every kind of diving conditions imaginable. No breathing problems -- ever. This time, after only (comparatively) light, gentle use, and no contact with saltwater whatsoever, it has developed this problem after only a few dozen dives.

So, I'm very hopeful to solicit speculation by learned tool-heads as to what has gone awry with this reg. Is this an LP seat problem? Maybe light scoring when it was serviced? Maybe a bad seat that had too low a durometer? Maybe a bad o-ring somewhere around the balance chamber? I am contemplating taking it apart and having a look see, but am leery about dissecting a balanced second what with the valve tube, balance chamber, and shuttle valve assembly complications. My experience is that these never allow "flipping the seat" anyway, and so I suspect I should get a 2nd stage overhaul kit before tearing it down.

Online photos of the overhaul kit (e.g. Part #345-2000, NE Scuba Supply), however, make it appear that there is a teflon seat included, but I can't find any confirmation for that. Likewise, while the web hosts a Zeagle reg repair manual of sorts, whoever scanned it failed to include the 2nd stage parts schematic, so I will be flying blind to some degree. If anyone would happen to know where I could source a schematic, I'd be very grateful.

I certainly am not averse to getting this reg serviced, but what I am really interested in is learning about what these symptoms suggest to experienced balanced 2nd repair techs and DIY'ers, and likewise learning more about the inner workings of B2's in the process. Yes, I've read Vance Harlow's SRMR and Peter Wolfinger's SRS, but I am still a novice at best. Finally, advice on what to look for, and maybe what to swap out would be greatly appreciated. If only Tom and Ray did regulators.

Thanks.

 

[LeadTurn_SD]

Since you've confirmed that your IP is correct (135 is "spec" for the Flathead VI) then the slight free flow you are describing is most likely a 2nd stage soft seat or orifice adjustment issue.

It is possible that the soft seat has "taken a set" (a groove has been engraved in the seat by the orifice). This does happen over time / dives. It is very possible that an orifice adjustment will stop the leak, and all will be good.... but if the groove is too deep then the seat just needs to be replaced.

The Zeagle 2nd stage service kit does come with a replacement seat.

I actually have two Zeagle ZX's I need to tear down and service.... they are doing the same thing yours is, but they are coming on 3 yrs since I last serviced them, so in my case it is just time to replace the seats, in your case it could possibly be a 2 minute job to adjust the orifice. I would do the orifice adjustment first (really just a 12 o'clock to 1 o'clock tightening of the orifice, just a slight turn) and see if this fixes it. If not, then you'll likely need to service it.

Good luck and let us know how it goes.

 

[cdharris]

... the slight free flow you are describing is most likely a 2nd stage soft seat or orifice adjustment issue. It is possible that the soft seat has "taken a set" ... this does happen over time / dives. It is very possible that an orifice adjustment will stop the leak, and all will be good.... but if the groove is too deep then the seat just needs to be replaced.

This is what I was thinking, but here is where I need/want to learn a bit more about how this operates. I am fairly habitual about backing off the BRK (although not perfect), and much more so since this last service. So I was thinking that this nearly took the hard seat out of contact with the soft seat, and so would help prevent premature "aging". Sort of like in the 70s when Scubapro put that nifty little piece of plastic on a "Chinese finger torture" cord -- so you could depress the purge and save the soft seat -- and included it with every regulator. What that did to the other parts I don't know, but at least hypothetically it delayed the need for service.

That's why I wondered if something else was up. Like I say though, I have not been THAT careful. But generally, I dive with it at almost full open anyway so a few dozens dives and less than a dozen months would mean this seat has taken a set WAY faster than my previous one. So is my thinking correct about backing off the BRK? I sure hope so or I don't know my reg basics nearly as well as I had thought.

I would do the orifice adjustment first (really just a 12 o'clock to 1 o'clock tightening of the orifice, just a slight turn) and see if this fixes it. If not, then you'll likely need to service it. The Zeagle 2nd stage service kit does come with a replacement seat.

This is very helpful info. Thanks. But it also raises another question or two. Essentially, adjusting the orifice is compensating for the seat taking a set. In other words, by adjusting the orifice I will be putting the hard seat to soft seat spacing -- when it is at full open -- about where it is now at, say, a full turn? Which will make me feel like I have done myself some good, but really it just moves the orifice closer to the soft seat, right? Which is likewise what the BRK does, but it is user adjustable "on the fly."

So this raises yet another question. At what point does adjusting the orifice no longer prevent free flow and why? Is it just limited by the thread depth of the orifice adjustment, or is there some other factor here I'm not seeing? I realize that if the soft seat is cut at some point, it is time for a new seat. Or if the "set" ceases to match the orifice, the seal is compromised. But is there any other factor that plays a role?

As the hard seat's depression (the "set") deepens, I assume the 2nd stage becomes less and less efficient at delivering air. That is, I suspect that this reduces (ever so slightly) the flow volume as the air flow path becomes more "tortuous" and turbulent thanks to the deeper depression in the soft seat. But I thought that teflon (and this seat is teflon, or some other "space age" plastic?) had better memory characteristics than the soft seats of the past. Which is why the behavior of this reg is so surprising to me.

In spite of the fact that I have tried to get educated about modern 2nd stage operation, my only overhaul experience is with non-balanced 2nds such as Conshelfs, Voits, and TUSA's from the 80s. As I'm sure you probably know, really early ones didn't allow any adjustment of the orifice. So I have a ways to go to get up to speed on my Zeagle and Hog 2nds. But thanks to your reassurances, I think I'll be adjusting the orifice on this reg real soon. Likewise, whatever results that brings, I'll also try my hand at an overhaul in the near future.

 

[LeadTurn_SD]

This is what I was thinking, but here is where I need/want to learn a bit more about how this operates. I am fairly habitual about backing off the BRK (although not perfect), and much more so since this last service. So I was thinking that this nearly took the hard seat out of contact with the soft seat, and so would help prevent premature "aging". Sort of like in the 70s when Scubapro put that nifty little piece of plastic on a "Chinese finger torture" cord -- so you could depress the purge and save the soft seat -- and included it with every regulator. What that did to the other parts I don't know, but at least hypothetically it delayed the need for service.

That's why I wondered if something else was up. Like I say though, I have not been THAT careful. But generally, I dive with it at almost full open anyway so a few dozens dives and less than a dozen months would mean this seat has taken a set WAY faster than my previous one. So is my thinking correct about backing off the BRK? I sure hope so or I don't know my reg basics nearly as well as I had thought.



This is very helpful info. Thanks. But it also raises another question or two. Essentially, adjusting the orifice is compensating for the seat taking a set. In other words, by adjusting the orifice I will be putting the hard seat to soft seat spacing -- when it is at full open -- about where it is now at, say, a full turn? Which will make me feel like I have done myself some good, but really it just moves the orifice closer to the soft seat, right? Which is likewise what the BRK does, but it is user adjustable "on the fly."

So this raises yet another question. At what point does adjusting the orifice no longer prevent free flow and why? Is it just limited by the thread depth of the orifice adjustment, or is there some other factor here I'm not seeing? I realize that if the soft seat is cut at some point, it is time for a new seat. Or if the "set" ceases to match the orifice, the seal is compromised. But is there any other factor that plays a role?

As the hard seat's depression (the "set") deepens, I assume the 2nd stage becomes less and less efficient at delivering air. That is, I suspect that this reduces (ever so slightly) the flow volume as the air flow path becomes more "tortuous" and turbulent thanks to the deeper depression in the soft seat. But I thought that teflon (and this seat is teflon, or some other "space age" plastic?) had better memory characteristics than the soft seats of the past. Which is why the behavior of this reg is so surprising to me.

In spite of the fact that I have tried to get educated about modern 2nd stage operation, my only overhaul experience is with non-balanced 2nds such as Conshelfs, Voits, and TUSA's from the 80s. As I'm sure you probably know, really early ones didn't allow any adjustment of the orifice. So I have a ways to go to get up to speed on my Zeagle and Hog 2nds. But thanks to your reassurances, I think I'll be adjusting the orifice on this reg real soon. Likewise, whatever results that brings, I'll also try my hand at an overhaul in the near future.

I really like the ZX's, they are great 2nd stages. I'm not sure why your ZX would start leaking so soon, but I have to say that my two are quite "finicky" in comparison to my "Gold Standard" Scubapro -109 or -156 2nd stages. Very similar technology, but my "old" Scubapro regs seem to go longer with less fuss, and less "fussiness".

I don't have the engineering background to answer your questions in the detail you want, just practical "DIY" answers will follow .

Storing your Reg: Backing off the adjusting knob does reduce pressure between the orifice and seat, and is a good thing to do when storing your regulator. There is still some pressure. But yes, that is the right way to prolong the life of the seat. Some folks will rig up a rubber band or something to partially depress the purge, others will actually back off the orifice completely for long-term storage.

As the 2nd stage soft seat develops a seating groove (which is usually very slight, by the way) you need to reestablish the pressure against it to create a seal. But the groove is very slight, and so we are only talking about moving the orifice a very tiny amount. Just a "tweak" should usually do it.

Turning the adjusting knob on the outside of the 2nd stage increases the spring pressure (does not move the orifice) and can often "stop" a tiny leak, but if you've had to turn the knob more than a turn you are beginning to sacrifice breathing performance... the demand lever operates against that spring.

If you turn the orifice in to increase pressure against the seat, you have the added effect of lowering the demand lever. And backing off the orifice raises the lever.

Lowering the demand lever past a certain point will decrease performance.

You want the lowest spring resistance and highest lever height that still allows "stable" (no leaks) performance.

So, you can often "stop" a leak by cranking down the adjusting knob, or tightening up the orifice.... but after a certain point you begin to effect performance and the 2nd stage breathes like a dog.

If it takes more than "just a tweak to stop the leak", you need to find out why. By this I mean a "tweak" of either the adjusting knob or orifice.

The most common cause is the soft seat, but you also need to examine (with magnification!) the orifice's sealing edge, and consider the balance chamber O-rings, spring, etc.

About your ZX: Properly tuned, your ZX "can" have a very small leak with the adjuster knob all the way out, but you should be able to completely stop the leak with just a slight turn of the knob. If this does not work, a very slight adjustment of the orifice should take care of the leak.

Also, the earlier ZX's had plastic orifices. Nice, spiffy METAL orifices are now available, and I'd recommend replacing the plastic orifice if yours still has one.

Again, if you need to do MORE than slight adjustments to stop the leak, then you need to find out WHY.

Best wishes.

 

[halocline]

The 2nd stage seat is usually one of the first things to show wear with time after a rebuild. If the guy who did the rebuild adjusted the orifice for the lowest possible cracking effort, which is good, then the seat is even more likely to leak a bit just as you described. It really sounds like you could simply tighten the orifice a small amount, maybe 1/8 to 1/4 turn, and go on your merry way.

It's really common for slight free flows with the adjusting knob all the way out in time; that's one of the nice things about user adjustment. You can set the orifice very light and use the adjusting knob to stop any slight flow.

The reason it maybe doesn't start on it's own but continues when you initiate breathing is venturi assist. Even with the venturi knob on minimum there's still lots of venturi effect in most high performance 2nd stages.

Leadturn's post was, as usual, right on the money and very thoughtfully explained!

 

[cdharris]

It is possible that the soft seat has "taken a set" (a groove has been engraved in the seat by the orifice). This does happen over time / dives. It is very possible that an orifice adjustment will stop the leak, and all will be good.... but if the groove is too deep then the seat just needs to be replaced.

Good luck and let us know how it goes.

I downloaded a schematic from frogkick and adjusted the orifice today. I was surprised to learn that my Scubatools hex inline adjuster didn't fit! But a 9/16" got the job done.

The results were not reproducible. Which is to say that I didn't get consistent results at different fractions of a turn. So it is looking like there may be something else going on. But I did eventually get it to a point where the free-flow was consistently gone for multiple breathing cycles. It wasn't that far (1/8th of a turn). Maybe that is all that was necessary. I'll dive it soon to see how it behaves.

In the meantime, I also overhauled a Conshelf 22 that was flawless. Something to be said for simplicity.

If this doesn't do the job, I feel ready now (thanks to your help and another SB'er who told me frogkick had a schematic) to tackle a complete 2nd stage overhaul. Should be fun. Wouldn't surprise me if it turns out an o-ring is acting up. On the other hand, I'm a believer in letting my reg tell me it's time.

Thanks again. And I'll keep you posted on how the 2nd acts in my local quarry.

 

[divad]

You may have a plastic orifice. I had one on a '95 Zeagle which became "fuzzy" after five years of use. I "dressed" it on a piece of SS, filed down the seat with an emory board, and it worked fine until I replaced it with a SS orifice and new seat.

 

[LeadTurn_SD]

.... I was surprised to learn that my Scubatools hex inline adjuster didn't fit! But a 9/16" got the job done.

The results were not reproducible. Which is to say that I didn't get consistent results at different fractions of a turn. So it is looking like there may be something else going on. But I did eventually get it to a point where the free-flow was consistently gone for multiple breathing cycles. It wasn't that far (1/8th of a turn). Maybe that is all that was necessary. I'll dive it soon to see how it behaves.....

Inconsistent results: What should happen is that turning the orifice clockwise will steadily and symmetrically increase the seating force and thus the cracking pressure. If this does not happen, then I would consider a close look at the sealing surfaces: the surface of the seat, and edge of the orifice. Then look at the poppet o-rings...

My ZX's are due for some TLC.... with both of them, I notice an inconsistent leak, and an inconsistent ability to stop the leak with either the adjusting knob (and the orifice). These are "spare" regs for me, so I've ignored their "bad" behavior until I get around to overhauling them.... I have lots of other regs to use, so I've been lazy about diagnosing their behavior.

Anyway, let us know how your 2nd behaves once you've tested it in the water.

Scubatools inline adjuster: Strange that it did not work... I use it on my ZX's (both the old plastic and new metal orifice)... it has a tapered hex fitting, so it should fit a range of hex orifice sizes...

Best wishes.

 

[cdharris]

Inconsistent results: What should happen is that turning the orifice clockwise will steadily and symmetrically increase the seating force and thus the cracking pressure. If this does not happen, then I would consider a close look at the sealing surfaces: the surface of the seat, and edge of the orifice. Then look at the poppet o-rings...

Anyway, let us know how your 2nd behaves once you've tested it in the water.

Scubatools inline adjuster: Strange that it did not work... I use it on my ZX's (both the old plastic and new metal orifice)... it has a tapered hex fitting, so it should fit a range of hex orifice sizes...

Best wishes.

My ZX does have a plastic orifice even though it is post-2000. And it is looking a bit ragged -- that & the venturi together might explain a lot. No wonder they upgraded to metal. I wonder if this was to reduce weight, cost, or wear on the soft seat? Obviously, in the long run it was a losing proposition or they wouldn't have upgraded to metal.

As far as the Scubatools Inline tool goes, it does NOT have a tapered hex fitting. Unidimensional. It seems I bought too early on that as well. But I think it's only three years old. Maybe they were clearing out NOS.

In any case, I probably am going to retire this Zeagle. What with the revelations of underfit diaphragm, sticking exhaust valve, plastic orifice and who knows what else, I'm thinking I'll just cut my loses. Lots of other brands sell for less with equal or better WOB numbers. I'm going to see if my new HOGs meet my needs and then decide what to do with this old clunker.

Thank you all. This has been a learning experience -- which for me is half the fun of scuba.

 

[keyshunter]

My ZX does have a plastic orifice even though it is post-2000. And it is looking a bit ragged -- that & the venturi together might explain a lot. No wonder they upgraded to metal. I wonder if this was to reduce weight, cost, or wear on the soft seat? Obviously, in the long run it was a losing proposition or they wouldn't have upgraded to metal.

It is the post 2000 Zeagles that have the plastic orifice. Before that, they were rebadged Apeks regs, which have a metal orifice. I don't know the reason for the move to a plastic orifice when they began making their own regs, but as you noted, it was not their best idea. It was fairly recently that they changed to a ss orifice. But for that, it is a good copy of the Apeks second stage, as are AL Legend and Titan LX (same ownership), Hog and several others.