How to properly use dive/predive lever and adjustment knob?

[Lorenzoid]

I recently acquired a HOG brand reg set that, unlike my previous regs, includes a dive/predive lever and an adjustment knob. I gave it a few test dives and realized I don't really understand how to properly use these features. The lever positions are labeled "+" and "-", and I set it to the "+" setting before entering the water. I didn't experience a freeflow at any time, so I figured I should just leave it on the "+" setting. I tried playing with the adjustment knob at depth, and it didn't seem to have a noticeable effect.

Procedures, suggestions, or pointers for using these features would be appreciated.


Also--and I'm not sure if this is related--the reg breathes a little wet when I turn my face up toward the surface. At first, I suspected it was due to mis-adjustment of the knob or lever, but experimenting with different positions did not seem to prevent this problem.

 

[buddhasummer]

Minus is before you start diving and then move it to positive upon descent, it's to prevent surface free flows. As for the wet breathing can't help you there. Often regs will breathe a little wet when inverted but that's not what you're describing.

 

[Lorenzoid]

OK, I suppose I knew that much. But what I am asking is whether there are any particular procedures that people recommend for using these features. For example, is it good practice to ALWAYS set the lever to the "-" or Pre-dive setting before entering the water, or only if one finds the reg is susceptible to freeflows? As I said, I experienced no freeflow problems, so I just left the lever set to the "+" setting for the remainder of my dives and never thought about it again.

Same question with the adjustment knob: Are there any particular procedures that people recommend? I left the knob in a more or or less midpoint position, but I have no idea if that is a good idea or not. As I said, adjusting it didn't seem to cause any noticeable difference in breathing effort.

 

[buddhasummer]

Ok, personally, I have mine on minus and the moment the reg goes in my mouth I turn it positive. My backup is always on minus. The adjustment knob on my primary is always turned all the way out, the only time I turn it in is if it starts to develop a leak. My backup is always turned all the way when diving (this in combination with Venturi on minus helps prevent free flows) when on dry land/storage etc I turn it all the way out to reduce spring pressure on the LP seat. As you have noticed the difference between adjustment knob turned all the way out or in does not make a big difference to ease of breathing.

 

[redacted]

There is a certain amount of regulator specific consideration but generally, I set that control to minus to reduce the severity of a freeflow when the regulator is not in my mouth. If freeflow is not a problem then I just leave it on plus. Some regs like my Scubapro Pilots are subjuect to freeflow quite severely when not in my mouth and UW so I usually keep them set to pre-dive until I am submerged. With some of those, I have to be extra careful when donating (and retrieving) them as they will freeflow quite strongly if you are inhaling as you remove the regulator from the mouth when in the dive position. I practice being very careful with the donation. Then I set the switch to pre-dive while in the recipients mouth before I retrieve it.

A well tuned, high performance reg should freeflow rather strongly if in the dive or plus position with nothing resisting the flow when the purge is pressed.

 

[Shorty esquire]

As someone else mentioned, set the red\venturi\pre-dive lever to negative when it's not in yoir mouth. I use the knob adjustment to help control my breathing. Also, wind the knob all the way out when storing the reg.

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[halocline]

Also--and I'm not sure if this is related--the reg breathes a little wet when I turn my face up toward the surface.

When you are facing the surface, the mouthpiece flange is the lowest point in the 2nd stage body, so any water that has seeped into the regulator will drain there, into your mouth. Water can seep in around the exhaust valve during exhalation, or there can be a leak around the mouthpiece flange, or sometimes between your lips and the mouthpiece, or there might be an actual leak in the regulator case. A little leakage into the reg from the exhaust valve is almost inevitable. A few drops when inverted is nothing to worry about. A mouthful of water, then you have a problem and you should get it fixed.

A very easy test is to connect the reg to a tank but leave the air off, then try to suck some air. You should get none; the reg should hold vacuum. If it doesn't look for the leak.

 

[fbk]

As someone else mentioned, set the red\venturi\pre-dive lever to negative when it's not in yoir mouth. I use the knob adjustment to help control my breathing. Also, wind the knob all the way out when storing the reg

Spot-on. The adjustment knob controls the cracking pressure, OP if yours has "no noticeable effect" then maybe your reg needs adjusting. Personally I like diving with mine turned all the way out (anticlockwise) making it so easy to breathe at depth, this position also keeps the pressure of the seat and prolongs its life when not in use. I have the same reg as a secondary so that one I dive with the adjustment closed so it is far less sensitive.

With the adjustment knob opened out the reg becomes much more prone to freeflows on the surface so the venturi/pre-dive lever helps prevent this. Switch it to "dive" position at the start of a dive.

 

[Lorenzoid]

OP here. Thanks for the replies so far. Question: It sounds like both the adjustment knob AND the venturi lever are intended to be used to minimize freeflows. Then why the need for BOTH of these features? I mean, why not just have a knob OR just have a lever?

 

[elan]

OP here. Thanks for the replies so far. Question: It sounds like both the adjustment knob AND the venturi lever are intended to be used to minimize freeflows. Then why the need for BOTH of these features? I mean, why not just have a knob OR just have a lever?

your assumption is incorrect, the knob and the lever have different functions, the knob determines how easy it is to start the air flowing and the lever how easy it is to maintain the air flowing. when set to minimum they minimize freeflowing.