regulator adjustment to prevent free flows?

[Yoyoguy]

Hello everyone.
I have an aqualung legend lx supreme. I know my primary reg has the cracking adjustment which helps prevent free flows at depth but I think my octopus is simply similar to an aqualung "titan" primary reg which does not have this feature. It has NOT free flowed on me yet, even in cooler waters (40F) at 100ft BUT I have always had it hanging off my side pointed in a downward direction (how regular recreational divers typically have it). I am starting to transition to a tech style rig/diving (if that's what you want to call it) where I have backplate and wing and my primary reg will have a 6 or 7ft hose and be wrapped around my head/tucked in my waist strap while my octo will have a bungee necklace around my neck. I have heard that due to this, the octo will now be in an upward position and could be more prone to free-flows. People have advised there are two ways to deal with this if it occurs. 1: buy an octo which has cracking adjustment OR 2: adjust your current octo. My current octo may already be set for colder waters as I have heard that is how they come on the aqualung "SUMPREME" models since these models are designed around diving in more cooler waters BUT just in case mine does free flow when I attempt to dive with this new set-up, I want to know I can make the adjustment. Is this something I can do myself? Our local dive shop is a pretty far drive from my house and extremely far from the lake I dive in. I will of course try the new rig exactly how it is and if it does not free flow great but I figure it wouldn't hurt to learn how to work on my own equipment anyways. If I can do this adjustment myself, how is it done? are there any write-ups with pictures? I don't want to make it "not safe" but I do trust my mechanical abilities and of course id test it in shallow waters with a pony bottle slung or have buddy near by before attempting any deeper dives. Thoughts? thanks everyone!

 

[Diver0001]

It sounds like you want to know more about regulator maintenance/adjustment in general and that you're not sure about the options you have to limit free flowing.

First, I would think if you took a good equipment specialty that you would be able to get hands-on answers to all of your questions. You don't need to become a regulator technician to do the things you want to do but you're right to look for help instead of trying to figure it out yourself.

Secondly, I detect a concern about free flows and/or responses to free flows. This is not an equipment issue and can't be solved with knowledge. To advise you over the internet is difficult, of course, but I would suggest finding an instructor who could really put you through your air sharing, problem solving and self-rescue skill-paces and raise the bar to the point where you come away feeling more confident that you can handle it if it were to happen. The long story is long so I'll spare you this right now, but the short story is that with proper training and procedures you'll learn to see a free flow (rare as they are) as a perfectly manageable event.

Good luck

R..

 

[Subcooled]

In "technical type diving" you will have two cylinders and two first stages and you can always close the cylinder valve to stop a free flow. It is even possible to open and close the valve as you need to breathe (or the valve can be turned "almost closed" giving you a constant but slow flow of gas). Gas sharing, as mentioned in the above post, is also one of the options. Hence free flows become pretty much a non-issue (unless they are frequent). You just need to reach the valves and be proficient in their use. This skill is part of tech training.

There are two types of free flows:
1) free flows originating at the first stage (intermediate pressure rises). Regular 1st stage/cylinder servicing and keeping cylinders dry from inside will help. There is nothing you can do to the 2nd stage to prevent this issue.
2) free flows originating at the second stage. Adjusting the 2nd stage may help.

Aqualung and Apeks regs should be similar, so you should be able to adjust the reg easily using a hex wrench. Locate the servicing manual and understand it.

This book may also be of interest to you: SCUBA REGULATOR MAINTENANCE AND REPAIR by Vance Harlow

 

[Yoyoguy]

It sounds like you want to know more about regulator maintenance/adjustment in general and that you're not sure about the options you have to limit free flowing.

First, I would think if you took a good equipment specialty that you would be able to get hands-on answers to all of your questions. You don't need to become a regulator technician to do the things you want to do but you're right to look for help instead of trying to figure it out yourself.

Secondly, I detect a concern about free flows and/or responses to free flows. This is not an equipment issue and can't be solved with knowledge. To advise you over the internet is difficult, of course, but I would suggest finding an instructor who could really put you through your air sharing, problem solving and self-rescue skill-paces and raise the bar to the point where you come away feeling more confident that you can handle it if it were to happen. The long story is long so I'll spare you this right now, but the short story is that with proper training and procedures you'll learn to see a free flow (rare as they are) as a perfectly manageable event.

Good luck

R..

thanks for the advice. I should have clarified. I have my open water advanced through PADI and have gone through those basic air sharing I have also read up on several different techniques outside of the PADI course. I have practiced with my buddy, whom I dive regularly, and I do feel confident I would handle a free flow situation well enough. So I did not mean to make it sound like a CONCERN or CONFIDENCE issue. It is not. I just remember reading somewhere that there adjustments which can be made on regulators that do not have cracking knobs to help prevent free flows in colder waters. I believe it has to do with the operating pressures of the second stage itself. You adjust it one way, which may allow it to breath easier BUT may make it a little more prone to freeflow and vice versa. Again, I believe the aqualung models with the "supreme" designation are pre-set to the setting which makes it breath a little more difficult but allows for less chance of a free flow so again I might not have any issue. I was just seeing if there were any good write-ups or books to make these adjustments so that way when I go to the lake next weekend and try my new gear set-up that if I do get freeflows I could mess with the adjustment to see if it helps "with out making it dangerous of course" as to prevent ruining the rest of the weekend. The dive shop is about 1.5 hours from my house and 3 hours from the lake I dive. Also, I was looking into possibly doing my own regulator maintenance but no one teaches those courses around here.

In "technical type diving" you will have two cylinders and two first stages and you can always close the cylinder valve to stop a free flow. It is even possible to open and close the valve as you need to breathe (or the valve can be turned "almost closed" giving you a constant but slow flow of gas). Gas sharing, as mentioned in the above post, is also one of the options. Hence free flows become pretty much a non-issue (unless they are frequent). You just need to reach the valves and be proficient in their use. This skill is part of tech training.

There are two types of free flows:
1) free flows originating at the first stage (intermediate pressure rises). Regular 1st stage/cylinder servicing and keeping cylinders dry from inside will help. There is nothing you can do to the 2nd stage to prevent this issue.
2) free flows originating at the second stage. Adjusting the 2nd stage may help.

Aqualung and Apeks regs should be similar, so you should be able to adjust the reg easily using a hex wrench. Locate the servicing manual and understand it.

This book may also be of interest to you: SCUBA REGULATOR MAINTENANCE AND REPAIR by Vance Harlow

thank you. I will have to look into this. I do plan on taking some technical diving courses but first comes my deep diver cert then a bunch of deep dives and dry suit training, and then technical diving so I am a ways out. I currently only have 40 dives logged, 10 of which have been to 75-100ft. Just trying to learn what I can, when I can and I was recommended to start switching over into technical style regulator/octo set-up to get used to it now which will place me ahead of the curve later.

 

[halocline]

On most 2nd stages there is a venturi assist adjustment. It's basically a vane inside the 2nd stage that disrupts linear air flow near the mouthpiece flange so that a free flow will not develop as easily. Your titan has one of these. If the cracking effort is properly adjusted for the IP of your first stage, this venturi adjustment should prevent freeflows.

You are right that with the bungee necklace, the mouthpiece will be pointing up as the regulator hangs from your neck. As long as it's filled with water this shouldn't matter. So when you start the dive, just pay attention, maybe turn the stage so that the mouthpiece is pointing sideways or slightly down, let it fill up with water, and off you go.

 

[Yoyoguy]

On most 2nd stages there is a venturi assist adjustment. It's basically a vane inside the 2nd stage that disrupts linear air flow near the mouthpiece flange so that a free flow will not develop as easily. Your titan has one of these. If the cracking effort is properly adjusted for the IP of your first stage, this venturi adjustment should prevent freeflows.

You are right that with the bungee necklace, the mouthpiece will be pointing up as the regulator hangs from your neck. As long as it's filled with water this shouldn't matter. So when you start the dive, just pay attention, maybe turn the stage so that the mouthpiece is pointing sideways or slightly down, let it fill up with water, and off you go.

thanks for the TIP!

 

[Diving Dubai]

I think I have the same aqualung secondary reg as you. It should have a simple lever on the side marked + - just move the lever to the - and it'll be fine. I've got + 200 dives with it in a necklace around my neck. Never had a free flow

 

[Patoux01]

- Have the regulator pointing downwards when you're on the surface, or you're in for a few surprised looks. Plus those bastards make a ton of noise when starting to flow just next to your face.
- Set the venturi so that it is in the "hard" position. That should prevent any flow. This still gives more than enough air. Once you switch to that regulator, turn the venturi. If you forget to do it, no big deal. You're not going to die because you forgot it.
- Make sure that when you swim, the mouthpiece is up (and not facing back). That should prevent bubbles when finning or facing current (due to the purge button)

At least, that's what I figured for myself... Maybe I'm a complete moron and should go take a course, but it seems to work fine like that.

 

[PfcAJ]

my octo will have a bungee necklace around my neck. I have heard that due to this, the octo will now be in an upward position and could be more prone to free-flows. People have advised there are two ways to deal with this if it occurs. 1: buy an octo which has cracking adjustment OR 2: adjust your current octo.

When you jump in the water, make sure the mouthpiece is facing down. Problem solved. Once the reg fills with water its not apt to freeflow and you can orient the mouthpiece however you want.