Tetra Pak Hoyer Frigus 400, Manual

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2-3
Tetra Pak
Hoyer
F40 03 CB 00
Fig. 3.3
Fig. 3.4
2
1
3
2
1
3
4
This is a two stage pump constructed with two
pistons of different sizes. The first stage (1) receives
and meters the quantity of mix set by the operator in
accordance with the hourly production required; the
second stage (2) receives mix dispensed by the first
with sanitised air let in between the two stages and
sends it all to the freezing cylinder.
As the difference in volume between the first and
the second stage (determined by piston size) does
not change depending on cylinder pressure and pump
speed, the quantity of air let in per unit of mix is
constant and depends on air pressure. By adjusting
the pressure of sanitised air , the operator therefore
controls the increase in volume, which remains
constant throughout the production cycle.
The pump is driven by an electric motor commanded
by an inverter (for speed changes) and incorporates
a pneumatically driven bypass(3) for CIP washing.
It works properly at relatively high pressures, so
3.1.2 Mix pump
that no extraction pump is needed coming off the
machine.
This is the most important part of the machine: an
upright pipe with a chrome coating on its inside walls,
surrounded by a jacket in which coolant gas flows
to cool down the cylinder. A dasher (1) with three
blades rotates inside it, scraping the chrome-plated
inside surface to ensure that frozen ice cream does
not build up on the walls. The top (2) and bottom
(3) ends of the cylinder are closed by two covers,
which incorporate the mix feed pipe (bottom) (3)
and the ice cream exit valve (top) (4).
Mix blended with sanitary air coming from the pump
flows into the bottom part of the cylinder (3) ; on its
way to the top it is whisked by the dasher (1) and
cooled by contact with the walls of the cylinder, kept
cold by the refrigerating plant. The ice cream forms
and then flows out of the ice cream outlet valve (4)
, which is controlled pneumatically to regulate the
pressure of ice cream in the cylinder.
In order to make sure the machine operates
correctly, it is important to be very careful not to
damage the cylinder, always making sure that the
3.1.3 Freezing cylinder
scraper blades are in perfect condition and have been
assembled correctly.