confused!!!

[*dave*]

You can get any second stage to freeflow by placing it mouthpiece up into water. It's usually managed by controlling the orientation of the second stage to insure the mouthpiece is pointed down when removing from your mouth or submerging.

If a first stage fails, it will most often fail to maintain a constant low pressure, building up pressure until it overwhelms the demand valve of the second stage. The same thing will happen if the first stage freezes and if not stopped, will drain your gas.

When diving in cold water (<50), I crank the adjustment knob on my secondary second stage down a bit. This prevents water flow from activating the purge. If I end up using it, I'll back the knob off for easier breathing.

is free flowing a big problem? i thought a regulator is designed for air ON DEMAND? not not on demand! ive heard alot of stories of free flowing regs on the surface but also underwater with a 1st stage malfunction is it likely it will happen?

 

[Web Monkey]

ive been looking into getting my own gear and heard about 2nd stage adjustable regulators. if i understand correctly as you descend you need to adjust it and as you ascend you need to adjust it as well. It sound kind of un needed? also whats the difference between the adjustment knob and the venturi lever? do you need both of them?
thanks

If you live near a friendly SCUBA shop, you don't "need" the adjustment knob.

Generally the service tech will setup your reg to breathe very easily, however setting it this way means that as the regulator ages or if you're facing into the current, it may start to freeflow. Turning the knob will stop this and make breathing a little more difficult.

If you don't plan on diving facing into the current, and have a place you can take your reg for minor adjustments, you can live a long and happy life with no knob. However if you don't mind spending the extra money, it's nice to have.

is free flowing a big problem? i thought a regulator is designed for air ON DEMAND? not not on demand! ive heard alot of stories of free flowing regs on the surface but also underwater with a 1st stage malfunction is it likely it will happen?

If you plan on diving in cold water, it's entirely possible for you to have a first stage freeflow, unless you buy a regulator that isn't prone to doing so. The Atomic M1, for example is extremely resistant to freezing. There are also other regulators designed for cold water, but I haven't used them.

If you're planning on warm water diving, it's still possible to have a freeflow, however this is generally caused by contamination or a lack of maintenance.

Terry

 

[Garrobo]

What Carchardon said.

 

[Mr Carcharodon]

BTW, Mr Carcharodon, there is no piston in a second stage, only a poppet and a demand lever. The knob on an adjustable second stage varies the spring pressure against the back of the poppet which keeps it closed when not inhaling. More pressure = harder breathing effort (cracking pressure).

Balance piston. I thought that would have made sense given the context.

 

[idocsteve]

I don't ever mess with it. I played with it alittle bit when I first started diving but now they are just all opened all the way and thats how I dive them. Only turn them back when current causes them to free flow.

^^ This is exactly what I was going to post.

Why set it for anything else other than full open unless you've got a free flow problem.

 

[walke121]

is free flowing a big problem? i thought a regulator is designed for air ON DEMAND? not not on demand! ive heard alot of stories of free flowing regs on the surface but also underwater with a 1st stage malfunction is it likely it will happen?

Free flow is usually only a problem I encounter when swimming into the current. The free flow isn't usually caused by a first stage malfunction. The current puts pressure on the purge button and the adjustments make the free flow stop.