Necessary to O2 clean 2.stage?

[the_dragon_no1]

To track of a little, but still in the subject.

As far as i know regarding particle impingement you need about 46 meter per second for it to start becoming a problem with high O2 concentrations, so how can we calculate this regarding a 2nd stage regulator, to possibly knock that issue out of the list?

To calulate the velocity we need a X-diameter hole to go from i kinda found out, but where from there im not sure.. Go by the smallest hole going into the 2nd stage, and take it from there?

 

[cerich]

50% on a dirty 2nd stage is gonna set it on fire? We're not talking valves or first stage here.

nobody is gonna ever get deep enough for the PPO2 in a second stage to be a issue.

Anybody, any manuf that really believe that a second stage needs to be oxygen clean is really not understanding very much..or just wants to sell higher priced parts, so an extra fee to "oxygen clean" a second stage. FUD selling at it's finest

 

[stuartv]

why do regular service? Service them when they start leaking or start breathing funny. No need to service them before that....

That is the philosophy I was following. The last time I got to go diving, one of my DR 2nd stages was freeflowing. I could barely hear it hissing at the surface. I bought them brand new, just over a year and half ago, and had never had them serviced. If that had happened before my first dive of a trip down in NC (or anywhere else where I traveled to dive), I would have been pretty annoyed. Sitting out a day of diving in order to, hopefully, get my reg fixed after we got back in, or otherwise renting a reg for the next day would have sucked. And buying a doubles set to have a spare 1st stage wouldn't have helped as it was a 2nd stage problem (as far as I know, anyway).

So, I think the short answer to your question of why do regular service is "so that I preemptively avoid having a problem when I'm about to do a dive I really want to do." Regular service with a test dive or two afterwards seems like the best way to avoid ever having a leak or funny breathing (when it matters).

 

[tbone1004]

@stuartv I prefer to do proper pretrip checks. Before trips, especially important ones, regs get their IP checked and validated, cracking pressure validated, and fully leak checked. Takes less than 5 minutes per regulator set, but no way am I going to rebuild everything every year or two when it doesn't ask for it

 

[Patoux01]

I carry a complete 2nd setup (1st stage, LPI, 2nd stage, SPG)

Also most dive ops I'd dive nowadays would have some reg I could borrow and that I'd be happy to use (not some crappy reg).

 

[packrat12]

Most of my recreational regs have gone 15+ years without service and still function well. The few times I have had them services, I had to adjust cracking pressure or fix a serious flaw in their service so that does not necessarily fix the "service it so it works" philosophy.

I also bring a spare reg set for serious dives and also all the tools and supplies necessary to do a minor fix like cracking pressure. I cannot think of a dive I have called due to a failed regulator.

As for O2, I just serviced 3 of my Hogs first stages and 2 second stages. The 1st stage gets the O2 treatment. The 2nd stage gets the same treatment but I do not worry about maintaining O2 cleanliness during assembly, just normal clean environment. I also treat my CCR loop this way, which also has LP O2 in it. Two of my Hogs 1st stage had been flooded for several months before I serviced them. They were in O2 use even during that time. Rust/corrosion was pretty bad but had no issues that they really were not O2 clean at that point. Go slow with pressurizing them and you will be fine.

 

[stuartv]

@stuartv I prefer to do proper pretrip checks. Before trips, especially important ones, regs get their IP checked and validated, cracking pressure validated, and fully leak checked. Takes less than 5 minutes per regulator set, but no way am I going to rebuild everything every year or two when it doesn't ask for it

And that's what you recommend to anyone here in the Basic Scuba forum?

I have an IP tester and think I could probably use it correctly to check that. But, how do I validate the cracking pressure?

Really, the question is, how can I know that I checked my regs before the trip and they won't check out fine and then the first dive be the time they finally cross the line from "fine" to "not fine"? If they're going to freeflow, there's always going to be a first dive where they do it, right? So, if I'm just continuing to use them until I have a problem, how can I know that that first time won't just happen to be 15 dives into a weeklong liveaboard?

I'm not trying to be argumentative (though I realize it probably sounds like it). I'm trying to understand what the warning signs are that you can actually test for and how to do the relevant tests. All I've ever heard people talk about is checking the IP to make sure it's not creeping up. And maybe that's what my recent leak/freeflow situation was, so testing it the day before would have alerted me. But, maybe my 2nd stage (barely) hissing was from something in the 2nd stage itself (I will find out when I pick them up)? In which case, how would I test to learn that that was about to start happening during pre-trip checking? My question is supposing that the 2nd stage hasn't started leaking (audibly) yet, but would start during my hypothetical trip.

The point being to catch the problem before it starts in order to prevent the problem starting during a trip. If there is no way to actually catch it before it starts, then regular service, or carrying a complete spare setup, and/or learning how to do your own service and carrying a service kit seems like the only options to be sure you don't end up having to try and borrow or rent regs during a trip.

I have a feeling the answer is that IP creep is pretty much always the issue here and that you can detect it well before it gets bad enough to actually cause a problem. So, if you test before a trip and don't have any creep, then you can be pretty well assured that it won't start happening and get bad enough to cause a problem during even a week or two of heavy diving. If so, then cool and I have definitely learned something (about what I should be checking on my regs periodically).

 

[the_dragon_no1]

And that's what you recommend to anyone here in the Basic Scuba forum?

I have an IP tester and think I could probably use it correctly to check that. But, how do I validate the cracking pressure?

Really, the question is, how can I know that I checked my regs before the trip and they won't check out fine and then the first dive be the time they finally cross the line from "fine" to "not fine"? If they're going to freeflow, there's always going to be a first dive where they do it, right? So, if I'm just continuing to use them until I have a problem, how can I know that that first time won't just happen to be 15 dives into a weeklong liveaboard?

I'm not trying to be argumentative (though I realize it probably sounds like it). I'm trying to understand what the warning signs are that you can actually test for and how to do the relevant tests. All I've ever heard people talk about is checking the IP to make sure it's not creeping up. And maybe that's what my recent leak/freeflow situation was, so testing it the day before would have alerted me. But, maybe my 2nd stage (barely) hissing was from something in the 2nd stage itself (I will find out when I pick them up)? In which case, how would I test to learn that that was about to start happening during pre-trip checking? My question is supposing that the 2nd stage hasn't started leaking (audibly) yet, but would start during my hypothetical trip.

The point being to catch the problem before it starts in order to prevent the problem starting during a trip. If there is no way to actually catch it before it starts, then regular service, or carrying a complete spare setup, and/or learning how to do your own service and carrying a service kit seems like the only options to be sure you don't end up having to try and borrow or rent regs during a trip.

I have a feeling the answer is that IP creep is pretty much always the issue here and that you can detect it well before it gets bad enough to actually cause a problem. So, if you test before a trip and don't have any creep, then you can be pretty well assured that it won't start happening and get bad enough to cause a problem during even a week or two of heavy diving. If so, then cool and I have definitely learned something (about what I should be checking on my regs periodically).

Didn't read it all here now (in a hurry), but you validate cracking pressure by sinking your 2nd stage in a tub of water with the mouthpiece pointing upwards. If you have a free flow knob on it, turn it all the way to "+" first.

Should be able to sink it an inch or so if i remember correctly now, before it starts blowing.

Google it and im shure you will find more info about this.

 

[tbone1004]

@stuartv yes that is what I recommend.
IP gauge every diver who owns their own regs should own. No ifs ands or buts with that. They're very cheap now that DGX is selling them unlike what they were 10 years ago, and there is literally no excuse for not having one if you own your own regs
Bubble checks should be done. If you own your own regs, you should have at least one tank of your own for checks like this
Cracking pressure can be done as mentioned above by checking in the water. Poseidon actually has in the official service manual for the Xstream a way to check cracking pressure against marks on the second stage housing by immersing in water and has been a technique used on the Jetstreams and Cyklons for decades. On "normal" looking regulators, you can do the same by measuring or eyeballing cracking pressure. This isn't something that has to be done and I only do this if I think something has changed, but if you own your own, you should figure out that variable. You can also build a magnehelic for like $10 with some air tubing, a ruler, some water *building a capillary gauge btw*, bit of aquarium air line tubing, and an old mouthpiece. Design of that given to me by @herman btw.

You can't always predict when they are going to fail, however if you do proper IP checks, you can pretty reliably say that they'll be OK for a while. HP seats are what you are really looking for to fail and those typically start to creep before they blow. IP gauge will validate that with creep and speed of lock up, you just have to be patient and leave it on for 5 mins

 

[victorzamora]

Stuart, if we get the reg demos to work out, I'll show you the basics on diagnosing upcoming issues. Almost always an issue will manifest itself as an increased IP (intermediate pressure, what the "LP" ports on your first stage put out). This "creep" upwards (IP creep) is an indication of one of several possible issues that all lead to a freeflowing second stage (unless you're diving the upside-downsie Poseidons or Oceanic Omegas).

The "dunk your second stage diaphragm-down in water so it freeflows and measure that" is checking for cracking pressure. Under ideal circumstances, you'd have a Magnahelic, but it's close enough. Cracking pressure is the amount of suction required on the second stage to cause it to flow, and ~1.1inH2O is a pretty good setting so "near enough an inch without it freeflowing dry" is about right.