Problem with Aqualung Titan LX

[Hallmac]

I had no problems before overhaul (and none during previous 5 years and 3 or 4 previous overhauls)
And yes, they adjusted it without checking in the water bath but it was hooked to a gauge. But it did work OK during 3 dives (more then 2 hours at 0-120ft) before problem developed again. Can something be lose inside so correct adjustment suddenly unadjust?

On the Titan ask them if they changed the poppet bearing? Under the control lever there is a nylon bearing for the poppet stem that wears. It is included in every service kit for a reason. Many techs get lazy and fail to replace it. That will allow the stem to shift around and give inconsistent performance.

On the Titan LX improper setting of the adjustment screw #31 can cause the same inconsistency.

 

[Couv]

With IP creep you'd think it would do it more before it was breathed off of and also you should see it in the octo. Not to say it can't be that, just that on the surface {no pun intended} that seems unlikely.

….well, not exactly. Lynne may have hit the nail on the head. Think of it this way. When two second stages are hooked up to one first stage, the one that is tuned with the lowest cracking pressure will free flow first when the IP is too high or creeps. As Herman said, an IP gauge is an invaluable tool, but if you don't have one and suspect IP creep, remove the second stage that free flows first and plug that port. If the other second stage begins to free flow, you have pretty much confirmed too high an IP or IP creep. Too high is usually indicated by free flow right away, and creep is indicated by free flow after a short period.

The OP stated that this happened right after service, and the only action taken was to adjust the second stage (probably ran the orifice in a bit.) However, because the problem returned, as others have pointed out, the problem most likely exist in the first stage. Before tearing into the first stage, I would give it a good 20 to 50 cycles to see if the IP stabilizes as there is a chance the LDS did not do a good job of cycling it after rebuild.

Cheers,

Couv

 

[svs]

Thank you all for the information. I’ll take reg to the shop this week and I’ll post about development. Reason I initially suspected second stage because octopus worked just fine. I used it for a while playing with second stage. Turning knob on a second stage all way toward negative (-) produced only a minuscule effect on a bubble stream. But when I stopped using octopus air flow stopped from it as suppose.
Now I’ll print this thread and I ask dive shop to check all items mentioned.
Thanks again.
SVS

 

[Couv]

Good luck, and please let us know how it turns out.

c

 

[tfsails]

Here's another scenario: Through experience, I've discovered that there are usually two places on an unbalanced second stage like this one where you can (usually) get the poppet to seal up and have a very good breathing effort.


The first would be where the nyloc nut on the end of the poppet stem has only one or two threads showing and the spring is not compressed very much. The spring cannot apply a whole lot of force to close the poppet because it is not compressed a whole lot. The poppet assembly is relatively long, the oriifce is not screwed in very far, and the reg is very easy to breathe--but also not real tightly sealed against free-flow.


The second scenario is when the nut is down about five threads or so on the poppet stem. This will compress the spring more and make it apply more force to the poppet seat when the demand lever is not depressed. The added force helps keep the seal between the orifice and the seat. The technician compensates for the relative shortness of the poppet assembly by screwing the orifice in to meet the poppet. Caution: this setup may make the reg a little harder to breathe on, so be aware of this.

I have "fixed" more than a few unbalanced second stages with this technique and haven't heard too many complaints from customers about the way the regs breathe, so it must be working.

As always, I'll close by stating that tuning a second stage is always a juggling act between ease of breathing, complete sealing when not inhaling, and the ability to purge the reg comfortably. You can't enhance one without detracting from another. As usual with the physical world, you can't get something for nothing.

Good luck!

 

[300bar]

Just one question,

When you hookup your reg.does it start the freeflow at once,or does it take some time.

 

[svs]

Just one question,

When you hookup your reg.does it start the freeflow at once,or does it take some time.

It takes sometime, often works OK during surface test but starts flowing during dive.

I took it to the dive shop and guess what? It worked just fine! IP around 145 and steady, no IP creep and no free flow. Tech also told that they had replaced all o-rings etc, during last overhaul. The only thing he did this time was to pop cover on adjustment knob on a second stage and adjusted spring inside a little. I promised to try it again but unfortunately it will probably not happened till August. So I’ll keep you informed. If it will leak again he promised to do another overhaul.