TUSA Imprex 1st stage harmonic

[LesN]

My brother is new to diving and bartered for some TUSA gear. His regulators are TUSA Imprex. Probably 12 years old. They breath fine, but the first stage is making a really loud harmonic squealing sound on each breath. It keeps doing it with a fresh tank. Then the noise stops after a while (which seems like a year). I suspect it is when the tank pressure has dropped to some pressure level. Anyone been into one of these regulators and have suggestions for repair? Thanks.

 

[rescuediver009]

It could be anumber of things from the orings not having enough grease to one of them beginning to fail. Sometimes something as simple as flipping the spring could make the difference. And even though I don't wish the parts bill of a tusa on anyone, has he had it serviced or does he know when it was last serviced? This might be the easiest solution.

 

[DA Aquamaster]

Not sure exactly what first stage you are talking about but I suspect it is a twin to the SP Mk 10. (Tabata made them for Scubapro). If that is the case the cause is almost always (99% of the time) inadequate lubrication of the HP o-ring.

 

[diverrick]

My wifes had the same problem. We fixed it by getting her a new SP reg setup. I couldn't stand to dive anywhere near her it was so piercing!

 

[LesN]

The regulator was supposedly factory serviced a little over a year ago. It was only used twice afterwards and left in storage.

So, are you talking about using the same silicone grease that I put on the O-ring of my camera housing? I have a tub of that.
Thanks.

 

[DA Aquamaster]

Possibly, depending on the grease or whether your reg was cleaned and lubed for nitrox use. Not all silicone grease is created equal - the type used for a static camera O-ring may not be ideal for use on a dynamic O-ring. And if O2 compatible lubes like Christolube were used, you should stay with them.

But lubing the HP o-ring correctly will require removing the ambient chamber, the spring, any shims present and the piston itself. You then should really use a piston bullet to re-insert the piston to avoid damaging the HP o-ring. This requires the piston bullet and the tools to remove the seat retainer. It is also sometimes problematic to remove the seat/seat retainer after the reg has been used as it does not always line up again perfectly and a small leak can develop if you end up with 2 separate seating grooves as they will overlap at 2 points.

If it has been over a year since it was serviced, getting it serviced is not a bad idea.

 

[waterwraith]

I used a tusa imprex reg a couple of times while diving in the local quarry. The imprex regs squealed and vibrated like crazy. All in All it was a really bad dive. Later me an the owner of the LDS were talking about weird things regs do and all I had to do was mention the TUSA imprex and he stopped me and began to describe in specific detail what that regs sounds like. He said that almost all of the TUSA imprex regs he had ever used or sold had this problem. He said that no matter what he did to them when he serviced them they would always vibrate and eventually start squealing again. His solution was to quit selling TUSA and switch to Aqualung and ScubaPro. I personally would never dive again with a tusa imprex reg.

 

[LesN]

I removed the threaded plug from the 1st stage that contains the inlet filter (unscrewed the Yoke screw and stuck a large allen wrench down through the hole). Under that plug was a unthreaded hex shaped metal plug, the middle section of it was some type of plastic. No O-ring in that part of the reg. Actaully, I didn't see much of anything. It appeared to me, after shining a light down into the hole that contained the hex plug, that the passageway lead right out to where the low pressure ports were. I take it this plug, with a machined notch at one end, is doing some or all of the regulation. Not sure how though, unless the plastic insert comes into play. Anyway, I put it all back just as it came apart and it still breaths. My pony tank only had 2000psi, so I didn't get to try it with a full tank, which is when it seems to make the most noise.