Scubapro S550 sticking on 1st exhale

[shogan]

Ok I have 2 scubapro S550 (both supposedly recently serviced) and both stick hard on the first exhale. After operation begins they seem fine. Left alone for a while they stick hard again.

Is this normal? If not does this sound like a misadjustment during the recent service?

 

[Bubbletrubble]

Replacement of the exhaust valve(s) is not typically part of a regular overhaul/servicing. Generally it's up to the discretion of the reg tech whether the piece requires replacement. During the overhaul, the exhaust valve is visualized and inspected for any rips/tears. Upon reassembly, the second stage is checked to make sure that the exhaust valve is functioning properly. FWIW, replacement of the exhaust valve is not part of the free-overhaul-parts-for-life policy that Scubapro, Aqualung, and other manufacturers have in place...so you can expect to pay a few extra bucks for that.

As long as the reg isn't breathing wet underwater and it permits exhalation without too much force on the first exhale, I probably wouldn't worry about it. If the exhaust valve is actually locking up, then take it back to the reg tech and tell him that the exhaust valves should have been changed (or cleaned) during the last overhaul. It's a straightforward fix and a good LDS should be willing to do this for you.

 

[rcs9250]

I have some Apek's that do it . I have Scubapro's and Aqualungs and Mares that don't. I've often wondered if I should put a shiny coating of silicone on the exhaust diaphragm and the seating area to stop it. Not gobbed on just a nice shiny coating like you do to camera O rings. Too much and you stand to get sand stuck in there and cause it to breathe wet.
It frees up with a good exhale but just a bit annoying. I've heard the complaint before.

 

[Scott L]

Ok I have 2 scubapro S550 (both supposedly recently serviced) and both stick hard on the first exhale. After operation begins they seem fine. Left alone for a while they stick hard again.

Is this normal? If not does this sound like a misadjustment during the recent service?

I have the S550 as an opcto on my back-up rig (guests) and it is always having issues. I will never again acquire a non-adjustable second stage...

 

[redacted]

That would be the exhaust valve sticking. That should not happen if the valve and its seat are clean. Next time you soak your reg on a tank, purge it and let the 2nd refill with water. Do this a number of time to, hopefully, clean off whatever is causing the sticking. If that does not work, you could either live with it or ask your tech to clean it.

 

[LeadTurn_SD]

I have some Apek's that do it . I have Scubapro's and Aqualungs and Mares that don't. I've often wondered if I should put a shiny coating of silicone on the exhaust diaphragm and the seating area to stop it. Not gobbed on just a nice shiny coating like you do to camera O rings. Too much and you stand to get sand stuck in there and cause it to breathe wet.
It frees up with a good exhale but just a bit annoying. I've heard the complaint before.

I've read in one of my repair manuals (Mares?) specifically not to do this. They mention not getting silicone grease on the diaphragm or exhaust valve. I think the bigger concern is the diaphragm slipping; I'd think the exhaust valve due to it's design is less likely to slip....

I think just cleaning as awap described is the best bet.

For what it is worth, I've had several regs do it. I believe that it is just a little impurity (salt, whatever) on the edge of the valve that does not wash off when you soak the reg after use (because the exhaust valve is sealed, and its edge traps the salt). When it dries, it gets "sticky" until the 1st exhale, then all is good.

Not a big deal, just annoying.

Best wishes

 

[DA Aquamaster]

Silicone grease or oil on a silicone valve will cause the material to expand. Not a lot but enough to potentially cause problems over time - that is why nobody recommends it.

More importantly, any excess grease creates the potential for sand, silt, etc to stick to the seat or valve and that can also cause issues.

In most cases an exhaust valve sticking on the initial exhalation is caused by salt or silt in the water drying and essentially gluing the valve to the seat. As AWAP suggests, the best solution is just to give it a good rinse after the dive and if it is already sticking, a nice warm water soak to help remove the accumulated gunk.

 

[shogan]

Well then sounds like I need to try a good cleaning.

 

[halocline]

You could try soaking it in hot water, and if you can get at the exhaust valve, you can gently lift it off the case and make sure clean water gets on the underside of the valve itself and the part of the case where it normally rests. That's the problem with just soaking; the water will have trouble getting to the exact spot it's sticking. Purging the reg while its under water will lift the valve, at least partially, off the case, but the air flowing will make it difficult for water to get in there.

When I have regs that do this, I live with it but take it as a sign that a thorough cleaning is in it's not-too-distant future.

 

[LeadTurn_SD]

Silicone grease or oil on a silicone valve will cause the material to expand. Not a lot but enough to potentially cause problems over time - that is why nobody recommends it....

I didn't know that! Thanks for posting that info.

I'd always assumed it was simply the concerns about the diaphragm slipping, or dirt accumulating on any "greased" surfaces that was the problem.

Best wishes.