SP A700 issues. Need advice!

[adamp69]

I live in Newfoundland, canada. So most of my diving is in water temps between 20 - 50 degrees F. So I bought what I was told was a very reliable cold water setup. A scuba pro A700 second stage, with a Mk17 first stage. Right from the very beginning, I've had the same issue. It dribbles out a little air in between breathes. I can dial down the adjustment a little, and the dribble stops. A few breathes later, and it starts again. Until eventually, it sticks and free flows. I should mention that this is only a cold water issue. It didn't happen while diving in Mexico.

The question I have is, my lds sent the regs back 3 times now. Every time it came back, it did the exact same thing. I thought it might have been me, so I had other ppl dive it, including the regulator tech at my Lds, and it did the same to him. It's still at SP now, and they can't find anything wrong with it. So my Lds has offered to replace it, but they're so pissed off with SP and their supplier, that they don't want me to get another SP. so, What do I go for? What is a comparable reg? I was thinking Apex. Maybe a XTX-200. What's a comparable reg in a comparable price range.

 

[ams511]

In that price range a high-level Apeks or Atomic would be comparable. My question is what are you using as an octo and did the octo have the same problem? The A700 is a metal regulator so I think you may be getting some condensation and freezing. The other question is are you purging the regs outside the water before the dive? That sometimes causes them to freeze up.

 

[Dan1219]

Same issue in Lake Michigan. Got rid of the SP A700/MK-17 and now use an Apeks XTX200 (1st and 2nd). 100 dives later- NO issues at all with the Apeks. I do use a SP mk25/s600 in warm water

 

[halocline]

The metal case 2nd should help prevent freezing, not contribute to it. You do have the most freeze-resistant SP 1st stage currently made, so it's hard to know what's going on. It sounds like you have some IP creep. It really should not be too hard to figure this out for any decent tech. You might ask them to set the IP at 120 PSI with a full tank. That would put somewhere around 127-130 with an empty tank. As someone once pointed out on this very forum, the SP balanced diaphragm (MK11-17) has a fairly significant IP rise as supply pressure falls. Just out of curiosity, does this tend to happen more as the tank empties?

Anyhow, if it were mine, I'd try to get a very good idea of what happens to IP over the supply range as as you take multiple breaths. I'd also try a different 2nd stage, specifically an old SP metal case 109 or balanced/adjustable. You'll have to find one used; I think Couv (that's his username) often has a couple for sale at a very reasonable price, expertly serviced and ready to go. If your IP is reasonably steady, and the older metal case 2nd solves the issue, that's a very bad sign for SP's attempt at re-introducung a metal case 2nd stage at a premium price.

Atomic regs are piston first stages, so I'm not sure that's ideal for cold water use. They do offer a sealed version which should tolerate very low water temps, but I don't really know. I'm a warm water diver. One thing I do know, the older SP metal case 2nds are considered among the most freeze-resistant 2nd stages ever, so believe it or not your answer might be in buying a 25 year old reg.

 

[adamp69]

I've actually never taken much notice to the tank pressures, but its never been right at the end of a dive. and its not like its when i'm scallop diving or breathing heavy. the last time it happened was while diving a wreck at almost 120ft. it was mid summer, and the water temps were the warmest they get. so i really wasnt expecting a problem. but at 120, there was a drastic temp drop. my computer read 28 degrees f. I even have it on my GoPro. you can hear the air dribbling between breathes, then it stopped solid. when i turned the adjustment knob up on full, it free flowed until i put in my octo, and then turned the knob all the way back. Im not up on all the internal workings of the regulators, and the IP's. but in the report my LDS got back from SP, SP was almost accusing me of Messing with the IP's myself. and I wouldnt know how even if i wanted to. So there is definetly something weird going on with that reg. what i'm wondering now, is if i should tell my LDS i want the same setup again. Or if i should go an Apex setup. and if so.....which one

 

[halocline]

I would suspect that your problem is related to IP creep, which means there's something wrong with your first stage. (IP, or intermediate pressure, is the pressure coming out of the first stage, going to the 2nd stage.) This is not rocket science, but unfortunately there is a huge amount of incompetence and BS within the 'professional' regulator servicing world, also some very competent and smart people, too.

So the first step is for one of those smarter and more competent people to track your IP through the entire tank pressure range with a gauge, making sure it's not slowly creeping up after each breath, especially as the tank empties. Sometimes you have to keep the gauge on the tank for several minutes to see this. If the IP is stable, then the next step is to try an all-metal 2nd stage. Metal transfers heat from the water and from your breath much more efficiently than does plastic. The freezing comes from expanding air in the valves of both the 1st and 2nd stages; this air is far colder than even the coldest water, so having a 2nd stage that conducts heat more efficiently will help to prevent 2nd stage freezing. The A700 was an attempt at making a modern metal 2nd stage inspired at least partially for cold-water use, but I'm not very familiar with it's design details. I know for a fact that the original SP metal case 2nd has excellent heat transfer and thus excellent resistance to freezing. If your reg freeze-flows with one of those, it's almost certainly a first stage issue. And they're cheap; less than $100 in top condition, fully serviced and ready to dive. So it's much less money than a new apeks set up, which by the way is plastic and may or may not solve your problem.

 

[ams511]

When i turned the adjustment knob up on full, it free flowed until i put in my octo, and then turned the knob all the way back.

Halo, you are way more experienced at this than I am but it would seem to me to be a second stage issue. I know the thread you are referring to about the IP changes over tank pressure on the MK-19 but his octo is not free-flowing. If the first stage is creeping too far outside of spec then wouldn't the octo freeflow also? I am thinking either a bad spring or a regulator tuned to a too low IP.

 

[halocline]

If his problem wasn't a freeze-up (or at least related to very cold water) I'd agree that the 2nd stage was suspect, and maybe it is. But this isn't a huge IP spike that would cause free flow in both 2nd stages, it's probably a gradual rise that's causing more flow and that's contributing to it just starting to freeze up when air is flowing well into the dive. Plus the depth is an indication; as depth increases, more air goes through the 1st stage, but the 2nd stage stays constant. But, basically I'm just guessing.

 

[axxel57]

Halo, you are way more experienced at this than I am but it would seem to me to be a second stage issue. I know the thread you are referring to about the IP changes over tank pressure on the MK-19 but his octo is not free-flowing. If the first stage is creeping too far outside of spec then wouldn't the octo freeflow also? I am thinking either a bad spring or a regulator tuned to a too low IP.

Yeah, I guess Halo is right, why should the octopus start to free flow if the usually more sensitive adjusted 2nd stage already does?

This happens normally only at complete failure of the 1st stage.

Still weird if the LDS could not trace the IP creep.

 

[ams511]

Here is an older thread about the same issue. Post #12 is interesting because it mentioned as a possible cause excess moisture in the gas.

EDIT: I checked out the ice diving weeki. There are some links to Antarctic diving here and here. It seems Poseidons score the best.