Scubapro A700 viva

[seedy]

Hi, stupid first Scubapro A700 owner question about the viva adjustment.
If it is showing Max or Min does this mean it is at max. or min. ?
Maybe this may be clearer, if the Viva lever is away from the face it reads
Min, but is this really Min or Max?It is not clear anywhere if have found.
and I haven't had a chance to dive it yet.
thanks as ever

 

[KaizerWilhelm]

It's saying "Max Flow" or "Min Flow". If you have it on the Min setting it will restrict flow and opposite if it's on Max.

 

[halocline]

It's saying "Max Flow" or "Min Flow". If you have it on the Min setting it will restrict flow and opposite if it's on Max.

You're right that max means "maximum venturi assist" but it's not really restricting air flow. It's just a vane that creates turbulence in the "throat" between the mouthpiece and reg body. The turbulence interrupts the linear movement of the air and keeps the pressure from dropping in that area. It's the pressure drop that creates the venturi affect.

So "min" is when the vane provides the most turbulence (it's oriented more or less at 90o to the airflow) and "min" is when it's oriented basically along the airflow, creating the least turbulence.

 

[seedy]

The A700 doesn't have that vane, I just had alook and it has an slot cut into
the air outlet tube(not sure of the correct terms) this slot rotates towards the mouth
about 30 degrees when indicated Max when indicated Min the slot is perpendicular (facing directly
up) to the mouth. So I assume this directs air more directly into the mouth on Max.

 

[halocline]

The A700 doesn't have that vane, I just had alook and it has an slot cut into
the air outlet tube(not sure of the correct terms) this slot rotates towards the mouth
about 30 degrees when indicated Max when indicated Min the slot is perpendicular (facing directly
up) to the mouth. So I assume this directs air more directly into the mouth on Max.

Sorry about that, I just assumed it was set up like most of the SP regs. Anyhow, it's doing the same thing; when the air is directed towards the mouthpiece, it's a more linear flow and causes a drop in pressure in the area. That's the venturi effect.

 

[Couv]

The slot functions the same as the vane. By directing the airflow toward the mouthpiece outlet air in the case is less turbulent which increases the venturi effect. Conversely, when the airflow is directed away from the mouthpiece opening, the air in the case is more turbulent and decreases the venturi effect. Usually during the dive, one wants to maximize the available airflow, however there are times such as when the regulator is not in the mouth that defeating the venturi assist is important.

Edit: Well, Matt beat me to it, but here is a neat video that may help to understand the function:

http://www.youtube.com/watch?v=dRb3RsdyWnE

 

[Scubapro Marcus]

I just bought a a700 and used it last night, I have a question it made a horn like sound when I breathed in when I was out of the water. The gauge was set at the min mark is that what caused that sound? In the water though it seemed to work fine?

 

[LeadTurn_SD]

I just bought a a700 and used it last night, I have a question it made a horn like sound when I breathed in when I was out of the water. The gauge was set at the min mark is that what caused that sound? In the water though it seemed to work fine?

Most likely you were hearing the diaphragm in the 2nd stage resonate. Some 2nd stages will do this out of the water when you inhale, it is no big deal. When in the water, the sound goes away because the water "dampens" the resonation.

As a reference, I think I have 14 different 2nd stages, 3 different brands, 5 different models I think about 1/4 of them are "honkers" All are just fine in the water.

Sometimes I think about trying to make them stop (removing the front cover, and changing the orientation of the diaphragm will sometimes do it), but have never bothered.

Best wishes.

 

[Scubapro Marcus]

Thanks
i just wanted to make sure my $700+ dive investment is not broke.I feel a little better now.

 

[divin'dog]

Thanks
i just wanted to make sure my $700+ dive investment is not broke.I feel a little better now.

I bought a new A700 and it honked when above water but it also was so bad that I had to take it out of my mouth because I also could not breathe through it... it would actually severely limit my breathing to the point that I would be trying hard to suck some air through it and could not comfortably breathe. Like breathing through a thin straw.

Anyway, there is a free diaphragm replacement for anyone that wants it... not really well publicized. Go to your LDS and they can get it replaced if you want to.