LESSON

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LESSON 06 DISH WASHING MACHINE OPERATIONS
January 1999
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Objectives Upon completion of this lesson, the
trainee will be able to a. Explain the proper
use of dish washing machines. b.
Demonstrate the safety factors involved with
the equipment. c. Explain the various types
of dish washing machines.
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d. Demonstrate the proper operating
procedures pertinent to dish washing
machines. e. Explain the proper Preventive
Maintenance Subsystem (PMS) checks pertinent to
dish washing machines.
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References. a. Food service Operations, NAVSUP
Pub 421.b. Food Service Sanitation Manual,
M6240.4A.c. Food Service Practical Handbook,
P4061.4.d. Enlisted Dining Facility
Master-at-Arms Handbook, NAVSUP Pub 520.
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Safety. a. All food service personnel assigned
to the scullery should 1) Be thoroughly
familiar with safety and operating instructions
of the machine. 2) Observe the following
precautions during operation of the
machine. a) Continually exercise
caution.
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b) Ensure protective covers are in place
on all external moving parts. c) Ensure
side doors are closed. d) Keep hands
off the inside mechanism of the
machine. e) If a dish rack becomes
jammed, turn off electric power and steam
before removing the rack.
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f) Wear rubber gloves and rubber
aprons. g) Report machine
malfunctions immediately.
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2. Types of dish washing machines. a. Single
tank. 1) Used in small ships, officer
messes and CPO messes. 2) Wash water
temperatures should be kept at 150-160 degrees
F. a) Necessary to control bacteria.
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3) Thermostats are provided in automatic
type machines. a) Prevents operation of the
machine when wash water temperatures to
drop below 150 degrees F. 4) Wash water
temperatures above 160 degrees F. results in
less efficient removal of starchy and food
particles.
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5) For best results, dinnerware /
silverware should be pre-washed by
hand. 6) Minimum time exposure to wash
water is dependent upon the type / make of
machine. 7) Final rinse comes from a outside
source
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a) As a hot spray of water at 180 - 195
degrees f. b) By a thermostatically
controlled booster heater. c)
Minimum time exposure to final rinse
depending upon the type/make of
machine.NOTE Conserve fresh water while
underway.
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b. Double tank dish washing machine. 1)
Used in activities serving more than 150
people. 2) Provided with separate wash and
rinse tanks. a) Add a final rinse of hot
water from an outside source.
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3) In some machines, a thermostatically
operated switch is installed in the rinse
tank. a) Prevents operation of the
machine when rinse water temperatures
fall below 175 degrees F.
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4) Operating procedures. a) Close the wash
and rinse tank drain valves. b) Fill
tanks up to the "Full" mark. 1. Check
the water level indicator. c) Inspect
the machine to ensure that
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1. Scrap screen is in place. 2. Spray
arms are capped and adjusted in order that
sprays of water directly hit the utensils.
d) Open the steam supply to the rinse
tank.
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1. For the rinse water temperature to reach
160 - 180 degrees F. 2. Leave the steam
supply open to maintain the proper
temperature. e) Open the steam and water
valves to the final rinse booster heater.
1. Adjust to maintain 180-195 degrees F.
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f) Ensure that the automatic detergent
dispenser is not empty. g) Start the
machine and run for 2 minutes. 1. To
thoroughly mix the detergent. 2. Gradually
increase the wash water temperature to 150-160
degrees F. NOTE Some machines do not run if
the rinse water temperature is below 180
degrees F.
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h) Look inside the machine (from the ends) to
ensure power sprays are operating
properly. i) Maintain and monitor proper
temperatures during operation. 1. Wash -
140-l60 degrees F. 2. Rinse - 160-180
degrees F. 3. Final rinse - 180-195 degrees F.
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FINAL RINSE SHALL NOT EXCEED 195 DEGREES
F j) If conveyor speed is properly
set 1. The utensils will receive a
7-second exposure in the wash tank and a
7-second exposure in the rinse tank.
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2. As the utensil rack reaches the end of the
machine it depresses a lever which will
activate the final rinse cycle. k) The
automatic detergent dispenser. 1.
Compensates for the dilution. 2. Compensates
for the increased food particle load in the
wash tank.
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l) For every 30-45 minutes of continuous
operation 1. Drain the wash
tank. 2. Empty and clean the scrap
screens. a. Refill wash tank and
replace scrap screens.
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c. Triple tank dish washing machine. 1)
May be found in some ashore activities. 2)
Procedures and governing standards same as
those of the double tank dish washing machine.
a) Except for the pre - wash section in
the triple tank. 1. Pre-wash water
temperatures should be 110 -l25 degrees
F.
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3. Preventive Maintenance Subsystem (PMS). a.
De-scaling of the dish washing machine. 1)
Should be a part of PMS. 2) Responsibility
of the Engineering Department. 3) Should
be performed weekly or as required in order to
remove mineral deposits which form inside the
machine. a. Mineral content in hard
water causes scale build-up.
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4) Soft water reduces frequent de- scaling
requirements. a) It contains minimal mineral
content. b) Distilled water (produced
by ships at sea) is soft. 5) Reasons for
de-scaling. a) Scale deposits interfere with
the efficient performance of the machine.
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b) Scale deposits provide a haven for
bacteria. 6) De-scaling procedures should be
closely supervised. 7) De-scaling
procedures. a) Fill the wash and rinse tanks
of the dish washing machine
1/2 full of water. b) Add the required
amount of de- scaler (acid) and wetting agent
to both tanks.
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1. 7 fluid oz. of orthophosphoric acid
(85) and 1/2 oz. of
wetting agent per gallon of water. c)
Complete filling the tanks to the overflow
level. d) Put scrap screens,
spray arms, and curtains in place. 1.
Scale deposits on all attachments must be
removed.
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e) Open the steam valve to the rinse tank to
bring the rinse water temperature to 180
degrees F. or higher. f) "Start" the machine
and operate for 1 hour. g) "Stop" the
machine and drain the tanks. h) Refill the
dish washing machine with water. 1. Add 2
cups dish washing compound to both tanks (or
as prescribed by the manufacturer).
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i) Bring rinse water temperature to 180
degrees F. or higher. j) "Start" the machine
and operate for 5 minutes. k) "Stop" the
machine and drain the tanks. l) Repeat steps
(h) through (k) using clear water as many times
as necessary until all traces of detergent and
de-scaler are removed.