Cressi MC7 Manuel D'instruction page 38

2.1 - Second stages Ellipse
The Ellipse second stage (in its various models) is a revolutionary
elliptical shaped lightweight (only 158 gr - the lightest of its class!)
"downstream" regulator featuring a futuristic design.
The regulator has a number of innovative features covered by
different patents.
It is manufactured in several versions, which are different not
only because of their first stages but also because the "Ellipse
Titanium" version has several components and inserts made of
titanium, a material which shows advanced mechanical charac-
teristics, and is incomparably light and resistant to corrosion.
All regulators have the same mechanical components and func-
tional characteristics as well as the same cage made of a new
elastic techno-polymer with excellent mechanical properties:
therefore, from now on, the regulator will be described simply by
calling it "Ellipse".
Ellipse was designed to supply air "on demand" i.e. only when
the diver inhales into the mouthpiece, creating a small vacuum
inside the regulator. This vacuum, acts on the ellipitical shaped,
variable-section diaphragm designed to have an increase in its
operating surface, and to keep the breathing effort as low as
possible. This ensures performance which is similar to that of
more expensive regulators.
fig. 6
The diaphragm, which has been depressed inside the second
stage, causes the center plate to contact a variable-profile lever
designed to optimize and dramatically reduce the friction result-
ing from the contact between lever and diaphragm, concentrat-
ing it into a single point of the plate. This minimizes friction
between the demand lever and the diaphragm plate. To carry
out this task, the special (patented) lever profile is assisted by a
swinging motion of the piston.
When activated, the lever opens the regulation valve. Air comes
out of the (adjustable) valve nozzle when the mechanism opens
flows into the injector which carries it directly into the mouth-
piece. The air is accelerated due to the Venturi effect which
causes a depression inside the second stage body. To avoid free
flow the injector portion directs a small opposite counterflow of
air toward the diaphragm.
A "valve-guiding" bushing made of a thermoplastic rubber,
placed inside the valve, performs the following two functions:
guides the spindle motion, reducing friction between the
mechanical elements each time the valve opens as well as to
protect the regulator in case the valve starts freezing at its most
crucial point. In this way, all the air required by the diver is only fed
inside the injector, thus avoiding any air loss in the spindle/valve-
housing coupling.
SECOND STAGES
37
fig. 7