Correct usage of Venturi effect lever

[Sbiriguda]

I just bought my new regulators and on both on main and secondary stages I have
1) knob: in order to tune if I want a "soft" or "hard" feeling while breathing
2) Venturi effect lever: in order to control Venturi effect
For the knobs, I would like to keep them always soft and don't touch them anymore on both stages
For the Venturi effect levers, I would like to keep the lever always open on the main stage and always closed on the emergy stage
Correct?
Some people say there is a higher consumption of air if the regulator is "too soft"

 

[hroark2112]

Adjust the regulator so you breathe best underwater. The more comfortable you are underwater the slower you’ll breathe. If you’re always working hard to breathe you’ll go through air faster than if you’re comfortable and relaxed.

 

[Jonny Wishbone]

some regs for example have both a venturi lever and an adjustment knob. example: Hollis 212 has both and Hollis 221 only has the venturi lever. you want the lever off on an octopus. if your octo has a knob too, turn it in some that way when you stride off a boat, dock or get into a current, the octo won't start to free flow on you. if the reg is in your mouth, lever and knob fully open. if you are heading into current enough to make your primary start to free flow you can turn the knob in a bit or adjust lever a bit.

 

[BoltSnap]

The Venturi should be off and the cracking effort adjustment turned in all the way when the second stage is out of your mouth. The venturi should be on (it is only "on" or "off") and the cracking effort adjustment know turned all the way out (easiest breathing without air leak) when the second stage is in your mouth breathing from it underwater.

 

[stuartv]

the cracking effort adjustment turned in all the way when the second stage is out of your mouth

I can't see any reason to have the cracking effort turned all the way in. On the primary 2nd stage, I don't see any reason to ever change it from all the way out for anything other than the example given previously - you're facing into a current and it's causing a freeflow.

On the alternate 2nd stage (aka the octo), yes, I don't think it's a bad idea to turn the cracking effort back from all the way out. But, it still doesn't need to be all the way in. One turn seems plenty.

Note: For storage, the venturi lever position does not matter, but the cracking effort adjustment should always be all the way out.

 

[Blasto]

First of all, remember it's only an adjustment to fine-tune the reg (a bit), not an extra control to operate. You should never need to adjust it between or during dives, unless you run into a freeflow.

I keep mine all of mine all the way out by default, venturi always on. Had some occasional freeflow issues, experimented and discovered it didn't matter one bit for those issues where the knob settings were, so decided to leave them all the way out.
They generally should be as far out as doesn't cause freeflows, and turned in when the current or something else causes freeflows.

Easier work of breathing ("soft") is always better, there is never any use for deliberately making it harder.

 

[John Bantin]

Why turn up the pressure on the 2nd-stage spring? If the cracking pressure needed to pull open the valve is too little - suck less hard!
The Venturi plus/minus simply disrupts the Venturi effect in the 2nd stage to avoid exponential free-flows at the surface. Leave it at minus on the octopus. I bet you couldn't tell the difference in the inhalation effort with it in either position at depth (unless you are an ANSTI machine).
I appreciate that dealers say they cannot sell a regulator in North America unless they have these features.

 

[kelemvor]

Note: For storage, the venturi lever position does not matter, but the cracking effort adjustment should always be all the way out.

I'm curious about that. Why store it with the adjustment in a particular position?

Why turn up the pressure on the 2nd-stage spring? If the cracking pressure needed to pull open the valve is too little - suck less hard!
The Venturi plus/minus simply disrupts the Venturi effect in the 2nd stage to avoid exponential free-flows at the surface. Leave it at minus on the octopus. I bet you couldn't tell the difference in the inhalation effort with it in either position at depth (unless you are an ANSTI machine).
I appreciate that dealers say they cannot sell a regulator in North America unless they have these features.

Salesmen say lots of things, doesn't make them true.

I agree that you'd be hard pressed to tell the difference in venturi lever position. At least, that's the case with my scubapro s600. I'd almost prefer a regulator which just permanently is in the "minus" position.

 

[Coztick]

I agree that you'd be hard pressed to tell the difference in venturi lever position. At least, that's the case with my scubapro s600. I'd almost prefer a regulator which just permanently is in the "minus" position.

SP 109 has cracking adjustment and no venturi lever.
After trying one I had to find two for me.
Just as good as my Apeks and way tougher.

 

[snowdog61]

Venturi assists in maintaining flow (holding the lever down) once flow has been initiated. That's why you can often stick a finger into the mouthpiece to stop a free flow on the surface (or turn your reg downwards underwater). Adjusting knob is for adjusting the seat pressure (cracking pressure) on your 2nd stage. I tune mine as close to the edge of leaking with the knob fully out and if it starts dribbling air you can always dial some pressure back in to get it seated completely. prior to storage, you should always dial it out to take as much of the seat pressure off and preserve the seat. Scuba Pro I know has an option to install the venturi in a two different orientations - the "rental" orientation doesn't provide as much venturi assistance which I supposed reduces the occurrence of surface free flows