Cressi MC9 Manuel D'instructions page 67

48 SECOND STAGES
of the piston spring. Practically, turning the knob clockwise
increases the breathing effort, while turning it anticlockwise
reduces it.
Two O-rings protect the mechanism from water seepage.
These, properly lubricated during manufacturing and maintenan-
ce, protect the mechanism thread from possible oxidation which
might affect the knob turning, making it difficult or even blocking
it. On the contrary, the knob is easily turned and the adjustmentof
breathing effort can always be carried out in an easy and precise
way.
Ellipse Black Balanced (picture 7) is not equipped with the knob to
adjust the breathing effort, although it features every details as
the other model.
The adjustable nozzle is located inside the valve and, when the
mechanism opens, the air comes out and is led directly into the
mouthpiece, thanks to the special care dedicated by designing
shape and inner walls finish of the regulator' s case.
In order not to make the vacuum inside the case too sudden (it
might "suck in" the diaphragm and cause free flow), the diaph-
ragm inside the valve shows a balancing perforation.
When the air flowing inside the injector towards the mouthpiece
increases, it causes a vacuum inside the regulator' s case due to
the air acceleration. This is called "Venturi effect" and flattens the
diaphragm, remarkably reducing the diver' s breathing effort.
The Venturi effect immediately stops as soon as the diver stops-
breathing. The diaphragm returns to its normal position, the lev-
ercomes up again pushed by its spring, and the nozzle is closed
by the piston.
In order to optimize the Venturi effect, Ellipse Balanced is sup-
plied with a flow deflector with two operating modes, clearly
shown by the scale on the regulator housing:
pre-dive "-" and dive "+" (picture 8). In first mode, a flow limiting
device placed in the mouthpiece inlet starts operating and inhibits
the Venturi effect, preventing free flow. In "+" mode, the Venturi
effect works at its best, increasing the air flow supplied to the
regulator to the maximum.
WARNING: Always remember to set the flow deflector' s
lever in pre-dive (-) mode when not using the regulator;
otherwise, an accidental collision, the regulator falling into
water, pressing the manual regulation button without having
the mouthpiece in one' s mouth, or suddenly taking the regu-
lator out of the mouth might operate a strong free flow, cau-
sing high air consumption.
fig. 7
The dive (+) position can only be used while diving and only
when the regulator is inside the mouth.
DIVE
When the diver exhales, the pressure inside the regulator' s case
increases, opening the angled conical large diameter exhaust
valve, allowing air to exit. The exhaust tee leads this air towards
PRE-DIVE
fig. 8