scubapro s550 mk17 free flow problem (cold water)

[DirtRider]

My friend and I got into diving about a year ago and logged a few dozen dives already. We did most of these in the chicago area and he has since moved to duluth minnesota. He's been diving in Lake Superior about a dozen times now and nearly half those times he has gotten either full or partial free flows with his regulator (scubapro s550/mk17). We were in lake michigan a few times down to 39 degrees at 130' this summer and didn't have a problem. The only time it happened here was at haigh quarry and it free flowed at 80' at about 50 degrees. He's in mostly low 40s temps now and occasionally dipping into upper 30s. He has had his regulator in for service since this happened. He's heard a few things to help this like not breathing through it until it is under the water and the obvious stuff about not using the purge. I have a mares abyss and I've never free flowed before but I haven't done as many cold dives as him.
Is the s550/mk17 adequate for cold water diving? Is there any kit or any special setting needing to be done to it in servicing for cold water diving? Any recommendations? It would suck for him to have to buy another reg with this one less than a year old.

Dan

 

[squidster]

That Regulator should not be free flowing,Its a very good cold water regulator,If he Gets it serviced it should be fine.
MK 17 is already enviromentally sealed.

 

[squidster]

Another thing it may be a second stage issuectopus:

 

[RJTY]

This is the same regulator I dive with in Florida. Upon taking a trip to Philly, I asked my LDS,(where I bought the reg.), How it would perform in cold water? He called SP, and they suggested that it be serviced first, there was an adjustment that should be made for cold water. I ended up not going, so I didnt have anything done.

 

[Dave in PA]

It is most likely a second stage issue, not a first stage issue. If the reg is not due for service, it can simply be adjusted by a technician. It should only take 1-2 minutes. I have the same reg and have adjusted mine twice. (I work PT at my LDS) The reg breathes great, has maybe .5 " of wc cracking pressure, but since it has no external adjustment like the S600 it can only be adjusted by the orifice.

BTW, you can convert it to an S600 by replacing about 8 parts inside.

 

[DirtRider]

Hi Dave, Thanks for the response. This isn't my reg so I'm not real familiar with it. The techs at his LDS I don't think are very good. Is this just an intermediate pressure screw or something similar to how I adjust my shadow octo+? What is this .5" of wc cracking pressure (and what is wc)? What does modifying to an s600 buy him and does that void warranty?

 

[crosing]

I had the same problem with that reg, diving in 40 degree quarry water, it freeflowed once, took it in for servicing, freeflowed again, took it back freeflowed again and sold it on ebay to someone in FL with the caveat that it did not perform well in cold water.

 

[scubanaked]

You might want to try a Sherwood Blizzard. I have three and dive in Michigan in 38 degree water and have not had it freeze yet. The guys that I dive with also have the Sherwood Blizzard, and no freeze ups.

 

[DA Aquamaster]

I have never seen or heard of a properly serviced and maintained Mk 17 freeflowing. If the external diaphragm that seals the ambient chamber is intact, there is no way for water to enter the reg and freeze up the reg and cause a freeflow.

I suppose if you have really moist air running through the reg it could happen, but it would have to come from liquid water inside the tank as the heat generated by compressing the air ensures it is extremely dry. ANd in that case the problem is with the tank not the regulator and no sealed reg in the world would be immune from freezing in that situation.

Second stages however can and do freeze up. This used to be an almost unheard of phenomenon back in the day when second stages used metal cases and metal air barrels. The metal cases and air barrelled ensured excellent heat transfer traits that endured the temp if the parts inside the reg stayed above freezing.

However now that dive companies have blessed us with all the advantages of compsite/graphite epoxy resin/technopolymer/whatever you want to call plastic this week second stages freezing, along with dry mouth, are significant problems.

Personally, I think plastic second stage cases are great for the manufacturer as they cost well under $5.00 each to produce - far less than the brass cased second stages they replaced. But they offer no real performance advantage and the weight savings is not nearly the benefit that people are led to believe as jaw fatigue is much more effectively addressed with a decent mouthpiece and proper hose lenght. But sadly, many divers are stupid and/or ignorant enough to believe the marketing hype that smaller and lighter is actually better. They basically deserve the dry mouth and freeze ups they have been inflicted with.

Given the choices available, the G250Hp and X650 are both good cold water second stages although the older metal air barreled G250 and even older metal cased Balanced Adjustable are even better. If you can still find one (discontinued in 2003), the D400 is exceptional both in performance and in cold water reliability.

 

[Dave in PA]

Dirt Rider, installing the parts to convert it to a user adjustable piece would most likely void any warranty. Also, this will really only help if it is a second stage free flow. I would suggest only having it adjusted, not converted. The wc is inches of water column. A relatively small amount of vacuum. A properly equiped shop will have a way of measuring and adjusting this setting.