Potential cause of HP seat failure

[SouthernSharktoothDiver]

Hey all,
Just recently my Tusa RS 1001 regset, which I purchased back in March and has around 20 dives on it, developed a slow leak on the second stages. I took it in to the shop that sold it to me, and the owner put it on his IP gauge. Sure enough, slow internal pressure creep resulting from HP seat failure. He asked me if I'd been using it on steel tanks, which I have not, I've only used it on aluminum tanks; however, my local fill guy is known for his "hot fills" some of which are in the 3400-3500 psi territory. I specifically asked him to not overfill mine past 3300, since my reg is yoke and can't handle above 232 bar, and as far as I can tell, the pressure has never been above 3400 psi. The owner of the dive shop says it would take more like 3600-3800, and more dives than I've put on the regset, to do the sort of damage that's happened here, and he has said he believes it is a defective part and that he'll see to it that it gets fixed, but I'm concerned something I've done/allowed may have caused this, since it seems like an extremely rapid failing of a new regset. Would fills 3400 (or, assuming perhaps my gauge is slightly off or some other error is in affect, 3500) psi cause this sort of thing? If not, can you think of anything else that would?
Thanks

 

[Geo7]

I'd agree with your technician that it is more likely some kind of particle contamination (rust, alu oxide, salt) that caused abrasion to the seat, or in the absence of that, that the seat was faulty.

My understanding is that those seats (TUSA RS 1001 = Scubapro Mk11) are made for 300 bar? After all, as soon as you convert it to DIN, it's a 300 bar (4350 PSI) rated reg.

 

[SouthernSharktoothDiver]

@Geo7 I believe it is the same as the Mk11, yes, though the owner said it can't handle the HP without being converted to DIN. I don't know enough to say if he's right or wrong.

Aside from that, I've been diving in fairly silty freshwater, and I always wash my regs afterwards, but I've been giving them less of a soak and more a rinse. I'll make a point of being more agressive about soaking them and see if that doesn't resolve the issue.

 

[lowwall]

A damaged HP seat is just one of several things that could be causing your first stage to not fully lock up.

The only way to know for sure is to have a competent tech take it apart and examine it.

 

[Jim Lapenta]

@Geo7 I believe it is the same as the Mk11, yes, though the owner said it can't handle the HP without being converted to DIN. I don't know enough to say if he's right or wrong.

Aside from that, I've been diving in fairly silty freshwater, and I always wash my regs afterwards, but I've been giving them less of a soak and more a rinse. I'll make a point of being more agressive about soaking them and see if that doesn't resolve the issue.

Converting it to DIN has nothing to do with the seat handling higher pressure. Nothing at all. And the DIN conversion for higher pressures is not as important as it was when yoke clamps themselves were made of different metal and rated at 3000 PSI.
Yoke regs will absolutely handle HP fills. All the DIN fitting does is replace the cylinder O-ring with a captured O-ring on the reg itself. The opening to the reg is the same size, uses the same filter, and is just going to minimize the risk of an O-ring failure at the cylinder connection.
The owner is full of crap and struggling to give you an answer that sounds intelligent but is in reality, compete BS.
If the reg IP is creeping there's every chance the seat was compromised in some way, perhaps even at the factory or by the tech who set it up.
Just because the reg is new, it doesn't mean it can't fail due to a materials issue.
I trained reg service techs and have written seven service manuals.

 

[lowwall]

I agree @Jim Lapenta . The cause of your IP creep had nothing to do with your yoke connection or what your tanks are made of.

If you really want to know the possible causes of IP creep for your diaphragm first stage, take a look at this thread: How to restore a Diaphragm First Stage with IP Creep

Enjoy

 

[Geo7]

Hi all, excellent points. However, a clarification: I don't think his tech meant the DIN vs yoke had anthing to do with it. The OP merely said he did not want fills beyond the rating of his yoke.

My point was that the yoke can be exchanged for a DIN connection, making this a 300 bar reg, and every remaining componenet (inclusing the seat is rated for 300 bar). That rules out pressure as the culprit.

The particle contamination that the tech was suspecting seems a common factor in failing seats, which is why he asked about steel tanks. Though aluminium oxide can do the same thing, as we suspected in @rsingler report. If that is not what happened, it leaves a faulty seat. We have seen that in severa brands as well.

The good news is that with some luck, the reg may just need the seat holder removed and a new seat installed. a 5 min job to insert a 5 $ part.

 

[Geo7]

@Geo7 I believe it is the same as the Mk11, yes, though the owner said it can't handle the HP without being converted to DIN. I don't know enough to say if he's right or wrong.

Aside from that, I've been diving in fairly silty freshwater, and I always wash my regs afterwards, but I've been giving them less of a soak and more a rinse. I'll make a point of being more agressive about soaking them and see if that doesn't resolve the issue.

Another clarification: The contamination in question refers to the quality of the air. Humidity in tanks can create rust and alumium oxide particles that can be abrasive to the seat.

The Mk11 is very well suited to the filthy freshwater. Dirty water and salt can cause problems with insufficient rinsing, but not to the seat. Well, with aggressive rinsing/soaking make sure you get no water inside, as that can create damage as well (lots of threads about this). So once you get a new seat, just continue what you were doing, provided the tanks and air you use are in fact clean.

 

[SouthernSharktoothDiver]

@Geo7 Wait, so your concern is that there may be aluminum oxide contamination coming from inside the tank....One of my tanks has a white, powdery buildup on the inside. The fellow that did the viz (not the guy that sold me my reg, different dive shop) said it was fine, that he'd hit it with a brush and it hadn't come off, so it wouldn't be an issue, but well, could that be the root cause?

 

[lowwall]

@Geo7 Wait, so your concern is that there may be aluminum oxide contamination coming from inside the tank....One of my tanks has a white, powdery buildup on the inside. The fellow that did the viz (not the guy that sold me my reg, different dive shop) said it was fine, that he'd hit it with a brush and it hadn't come off, so it wouldn't be an issue, but well, could that be the root cause?

Take a flashlight, remove your first stage dust cap (and maybe the yoke knob), and look at sintered filter where the tank air goes into the first stage.

It should be clean, shiny metal. If there's white powder or rust flakes or any obvious contaminants, then you have a problem with your tank. But a clogged filter is more likely to cause breathing problems (especially at low tank pressures) than IP creep.

IMO, you are wasting your time speculating about the cause. It will take a tech a few minutes to identify the problem. Given the age of the reg, it's likely a manufacturing or assembly defect. Hopefully in a replaceable part like the seat or an o-ring. Either way it should still be under warranty so shouldn't cost you anything.