Problems with backup reg around my neck.

[svidlano]

Although this is not strictly DIR related question I've posted it here because I believe that you have the most experience with such regulator position.

Last weekend I tried long hose configuration. I use Scubapro MK25 first stage reg, S600 as primary and R190 as backup reg.

My regs have been bought last year, have some 40-50 dives and have not been serviced yet. I've noticed that R190 is rather inclined to free-flowing. It starts to free-flow when it hits the water with its front side or when I press the purge button on the surface. Unlike the R190, S600 is much less "nervous" and when I let go of the purge button it stops immediately.

After I've positioned R190 under my neck I had problems jumping off the boat. When I hit the water R190 always starts to free-flow (because it hits the water with it's front side). So now I jump with R190 in my mouth and then switch to my primary.

Is that type of behavior to be expected?

 

[SDAnderson]

The problem is with the regulator, not where you're stowing it. The R190 is semi-user adjustable, if you can't set it so that it won't free-flow you should have it serviced. Tell the tech what the problem is and that you want the first stage tuned for greatest reliability, not peak performance. He can set the IP at the lower end of the spectrum where it's less likely to cause freeflows an make certain that the R190 is working smoothly.

You've got good regulators and this problem is fixable, so don't give up.

 

[Spectre]

It's nice to have a somewhat adjustable reg as your backup; for example I use an ATX40. I don't get the full adjustments that I can with my ATX50; but I have the venturi lever to 'detune' the reg when I'm not using it.

Without something on the fly adjustable; you'd need to detune the reg a little bit so that it's not as sensitive as your primary reg. This actually is a common practice for octopus regs anyway, but it's a better option in this case. The detuning of octos makes it a little harder to breathe. If that's the reg you are donating; they can likely overbreathe it when the diver receiving the donated regulator is stressed. However donating the primary and switching to a detuned backup gives the stressed diver the regulator that is tuned for easier breathing, and gives you, the less stressed, the one with a little more breathing resistance.

Oh... and it's most likely not the intermediate pressure that needs adjusting... remember that is going to effect -both- your regulators if you are diving a single. The cracking pressure in the second stage [the amount of inhaled force needed to depress the lever and get the gas flowing] is what would need to be adjusted on the second stage. It'd be really easy to do yourself; but if you aren't familiar with the basic design of your reg, or you are uncomfortable with messing with it, you'd definately want to take it to a tech. [i would, however, suggest that knowing how your regs work is not a bad thing, even if you don't want to mess with them yourself].

 

[svidlano]

Oh... and it's most likely not the intermediate pressure that needs adjusting... remember that is going to effect -both- your regulators if you are diving a single. The cracking pressure in the second stage [the amount of inhaled force needed to depress the lever and get the gas flowing] is what would need to be adjusted on the second stage. It'd be really easy to do yourself; but if you aren't familiar with the basic design of your reg, or you are uncomfortable with messing with it, you'd definately want to take it to a tech. [i would, however, suggest that knowing how your regs work is not a bad thing, even if you don't want to mess with them yourself].

I thought so.

I believe that a screw regulating this is accessible after I remove the hose from the 2nd stage. What I'm not sure about is how much I can close it without endangering myself). Should I turn half a turn, full turn or something else?
I know I can try and see, but before that I'd like to have the general idea – is it 1/8 of a turn or is it OK to do even 2-3 turns.

 

[Spectre]

yes, most likely the adjustment screw is accessible when you take the hose off. It's a royal pain in the butt to adjust it without an inline adjustment tool; as you have to take the hose off, adjust, put the hose on, turn the gas on, test, turn the gas off, purge, repeat.

You're -definately- talking about a miniscule level of turning. If you take the faceplace and everything off, you'll see the lever and you'll see that turning the screw will change the lever high dramatically. You only want to change it a teeny bit.

I set my primary regs to freeflow when purged, and turn off when the venturi lever is flipped to '-'. The 'true' way is to dunk it; face up, and have it set to freeflow when it gets a few inches under water, and to stop when you turn it so that it's facing down.

Either method you use; you want to set it there then turn it just a tad more to keep it from actually freeflowing. You'll 'know' by breathing off it. Get it tuned precisely, see what it feels like breathing off it, then back it off just a tad so that it doesn't freeflow during the tests, and breathe test it again. You'll be able to tell if you made the breathing resistance a little harder, or a lot harder.

 

[redacted]

I thought so.

I believe that a screw regulating this is accessible after I remove the hose from the 2nd stage. What I'm not sure about is how much I can close it without endangering myself). Should I turn half a turn, full turn or something else?
I know I can try and see, but before that I'd like to have the general idea – is it 1/8 of a turn or is it OK to do even 2-3 turns.

If you can get to the orifice (screw), the adjustment is fairly simple. But even an 1/8 of a turn is on the high side. As I get close to the right setting (I don't have the inline tool) I make 1/12 turn adjustments on mine. Make sure you depress the purge button as you turn the 'screw' so the seat is not in contact with the orifice as you make the adjustment as the knife edge may cut the seat. Make your adjustment, reconnect the hose (hand tight) and test it after each adjustment. A sink works OK for this. I would expect the freeflow problem to be remedied with one adjustment, two at the most. You may also have to pay more attention to the orientation of that reg as you enter the water. Make sure the mouthpiece is pointed down rather than the purge button.

Clockwise adjustment increases cracking pressure.

 

[cdennyb]

Maybe you should think about moving over to a G250 for your backup. The reason so many DIR type divers use it, is it's totally adjustable with both venturi adjustment and the knob on the side for free flow. I love mine. Even in the river it won't free flow unless I turn it upside down.
I liked it so much and it was so adjustable, I gave my D400 to my daughter and kept both my regs the G250 type with MK20 first stages.
just my rig.
db