b. Sodium chromate (anhydrous, technical, conforming to Technical Specification O-S-588) is added to insulate
metal surfaces from the corrosive environment. In addition, the chromate helps to maintain proper alkalinity and acts as
an oxygen scavenger.
Chromate chemicals will not be used with glycol-type antifreeze. These chemicals react with
each other to form harmful acids and heavy sludge deposits.
c. Sodium tetraphosphate, Technical, Specification O-S-635, tends to hold scale-forming elements in suspension
and to convert the sludge-forming elements into a relatively harmless solution, which can be removed by periodic
cleaning of the cooling system.
d. Antifreeze compound conforming to Military Specification MIL-A-46153 (Antifreeze, Ethylene Glycol, Heavy
Duty, Single Package) is a mixture of special kinds of alcohols called "glycols." A 60 percent solution which protects to -
55 , boils at about 230 , compared to 212 , for pure water. Solutions containing more than 60 percent antifreeze
give less protection. Antifreeze compound without any water added will freeze at about 0 . Where temperatures below
-55 are expected, antifreeze compound conforming to Military Specification MIL-A-11755 (Antifreeze, Arctic Type) will
be used undiluted.
Do not mix commercial antifreezes with each other or with military specification-type
e. Cleaning compound conforming to Military Specification MIILC-10597 (Cleaning Compound with Conditioner and
Inhibitor for Engine Cooling Systems), contains various chemicals to clean and condition engine cooling systems. For a
complete description of the kit, see paragraph 2-11.b.
2-5. Summer Treatment.
a. Prior to filling with clean, fresh water and corrosion inhibitor, the cooling system must be cleaned as outlined in
Chromates must be handled properly as they are classified as a health hazard. If any
chromate, solid or spray, comes in contact with eyes, immediately flush eyes and affected
area with plenty of fresh water. See doctor immediately. If contact is made with the skin, use
soap and water to wash the affected skin area. See a doctor immediately. If chromate dust or
spray is inhaled, see a doctor immediately. Protective equipment such as goggles, face
shields, rubber gloves, aprons, and dust respirators should be used.
b. Fill system to 1/3 capacity with clean, fresh water.
c. Dissolve in water 1/2 ounce sodium chromate (Specification O-S-588) for each gallon capacity and add solution
to cooling system. Replenish also at this rate. (For example, when the cooling system capacity is 10 gallons, use 5
ounces of chromate.)
d. Dissolve in water 3 3/4 ounces antifreeze extender additive (Military Specification MIL-A-53009) for every gallon
capacity. (For example, when cooling system capacity is 10 gallons, use 37 1/2 ounces extender additive.)
e. Fill to capacity with clean, fresh water.
f. Run engine at fast idle speed for at least 5 minutes to mix solution.