Scotsman MXG 327, Руководство по обслуживанию

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Page 25
Page 25
The 9th key is used to supply power to the water
pump for the first 15 seconds of the defrost cycle
- position OFF - or for the first 30 seconds -
position ON.
The 10th key is used to modify the CUT-OUT
condensing temperature from 70
°
C (160
°
F) for
the air cooled versions - ON position - to 60
°
C
(140
°
F) - OFF position - for the water cooled
versions.
H. WATER SPRAY SYSTEM
Through its nozzles, the water pumped, is sprayed
in each individual cup to be frozen into ice.
It consists of one spray tube wheve are located
several spray nozzles.
I. WATER PUMP
The water pump operates continually throughout
the freezing cycle and on the first 15 or 30
seconds of the defrost cycle so to such the
remaining water from the sump tank (reach in
mineral salts) and drain it out.
During the freezing cycle the pump primes the
water from the sump to the spray system and
through the spray nozzles sprays it into the inverted
cup molds to be frozen into crystal clear ice cubes.
It is recommended that the pump motor bearings
be checked at least every six months.
J. WATER INLET SOLENOID VALVE -
3/4 GAS MALE FITTING
The water inlet solenoid valve is activated by the
micro processor of the P.C. BOARD during the
first 5 minutes of water filling phase and as well
during the defrost cycle.
When energized it allows a metered amount of
incoming water to flow overt he evaporator cavity
to assist the hot gas in defrosting the ice cubes.
The water running over the evaporator cavity drops
by gravity, through the dribbler holes of the platen,
into the sump reservoir where it will be sucked by
the water pump and primed to the spray system.
K. HOT GAS SOLENOID VALVE
The hot gas solenoid valve consists basically in
two parts: the valve body and the valve coil.
Located on the hot gas line, this valve is energized
through the micro processor of P.C. BOARD
during the defrost cycle and as well during the
water filling phase.
During the defrost cycle the hot gas valve coil is
activated so to attract the hot gas valve piston in
order to give way to the hot gas discharged from
the compressor to flow directly into the evaporator
serpentine to defrost the formed ice cubes.
L. FAN MOTOR (Air cooled version)
The fan motor is controlled through the P.C.
BOARD and the TRIAC by the condenser tempe-
rature sensor. Normally it operates only during
the freezing cycle to draw cooling air through the
condenser fins.
In the second part of the freezing cycle, the fan
motor can run at intermittance as the condenser
pressure must be kept between two corresponding
head pressure values (16
÷
18 bars- 225
÷
250 psig).
M. COMPRESSOR
The hermetic compressor is the heart of the
refrigerant system and it is used to circulate and
retrieve the refrigerant throughout the entire system.
It compresses the low pressure refrigerant vapor
causing its temperature to rise and become high
pressure hot vapor which is then released through
the discharge valve.
N. WATER DRAIN SOLENOID VALVE
The water drain solenoid valve, electrically
connected in parallel to the water inlet and to the
hot gas solenoid valves, is energized for all the
length of the defrost cycle.
By means of the water pump, that remains
energized for 30 seconds at the beginning of the
defrost cycle, it allows the drain out of all remaining
water (rich of minerals deposited during the
previous freezing cycle) from the sump tank.
By doing so it allows to the ice maker to make
every new freezing cycle with new fresh water,
avoiding thereby the accumulation of sediments
and scales, which soon or later will cause the partial
or total clogging of the water system on the unit.