operated machines, wash and rinse intervals are
controlled by the operator who should allow a 40-second
wash and a 10-second rinse.
To control the bacteria to a satisfactory minimum in
single-tank machines, it is necessary that the
temperature of the wash water in the tank be 140°F to
160°F. Therefore, a thermostat is provided in the
automatic machines to prevent operation when the
temperature of the water falls below 140°F.
Rinsing is done by means of spraying hot water on
the dishes from an outside source and is controlled by
an adjustable automatic steam-mixing valve that
maintains the temperature of the rinse water between
180°F to 195°F.
Double-tank machines (fig. 4-14) are available with
several different capacities and are used when more than
150 persons are to be served. These machines are
provided with separate wash and rinse tanks. They also
have a final rinse of hot water that is sprayed on the
dishes from an outside source. This spray is opened by
the racks passing through the machine. The spray
automatically closes when the rinse cycle is completed.
The final rinse is controlled by an adjustable automatic
steam-mixing valve that maintains the temperature
between 180°F to 195°F. Double-tank machines are
also equipped with a thermostatically operated switch in
the rinse tank that prevents operation of the machine if
the temperature of the rinse water falls below 180°F.
The racks pass through the machine automatically by
means of conveyor chains. The two-tank dishwashing
machine should be timed so that the utensils are exposed
to the machine sprays for not less than 40 seconds
(20-second wash, 20-second rinse).
Triple-tank Dishwashing Machines
Some shore activities have triple-tank dishwashing
machines installed. The procedures of operation are
basically the same as with double-tank machines with
the following exceptions:
l The dishwashing machine consists of prewash,
wash, and rinse sections with a final rinse.
. Refer to the manufacturers operating and
instruction manual for the preset temperatures of the
Figure 4-14.Double-tank dishwashing machine.