The chemical additive MIL-A-53009 consists of a blend of inhibitor chemicals in a liquid solution. The inhibitors neutralize the acidic by-products that result from the combustion blow-by gases that leak into the coolant. To prevent corrosion, the inhibitors form protective layers on the metal surfaces of the cooling system. Do not use MIL-A-53009 and inhibited anti-freeze together in the same engine cooling system. Overtreatment with MIL-A-53009 and inhibited antifreeze can result in the formation of deposits in heat exchangers. This condition can cause overheating. Refer to Naval Ships Technical Manual, chapter 233, for information concerning the required conversion procedures.

At the time of the writing of this manual, the five types of corrosion inhibitor treatments we have just discussed were those authorized for use in naval engine cooling systems. As an Engineman, you must stay informed as to the current requirements for your ship. For detailed guidance on the type of corrosion inhibitor that you must use as well as the required testing and treatment procedures, refer to the Naval Ships Technical Manual, chapter 233.

SAFETY PRECAUTIONS

Sodium chromate, NALCOOL 2000, inhibited antifreeze, and MIL-A-53009 are hazardous chemicals. You must avoid any contact with the skin or eyes. If your eyes have been in contact with these chemicals, you must flush your eyes with potable water for at least 15 minutes immediately after exposure. Seek medical attention. If areas of your skin have been affected, flush your skin with cold water immediately after exposure. Then wash the areas thoroughly with soap and water. Avoid breathing the solution spray or the sodium chromate powder. These chemicals are poisonous when taken internally.

When you are handling these chemicals, you should wear protective clothing, such as a face shield, rubber gloves, and apron. When handling sodium chromate powder, you should also wear a dust respirator.

Soluble oil is less hazardous than the other inhibitors; however, it can be irritating to your skin and eyes. While handling soluble oil, use the same protective equipment as you would when you are handling the other corrosion inhibitors. If your skin or eyes should come into contact with soluble oil, you should also use the same removal procedures you would use for the other chemicals. You must always take suitable precautions to prevent contamination of the ships potable freshwater system. You must especially prevent backflow of the engine cooling water through the filling connection. Remember, specifications require that an air gap remain between the freshwater supply and the fill connection. This design must not be altered. Corrosion-inhibitor-treated coolants must be disposed of according to the procedures in the Environmental and Natural Resources Protection Manual, OPNAVINST 5090.1 (latest edition) and the Naval Ships Technical Manual, chapter 593.

SUMMARY

In this chapter, we have covered three types of closed cooling systems: (1) heat exchanger, (2) keel cooler, and (3) radiator and fan. The heat exchanger and keel cooling systems use fresh water to cool the engine and seawater to cool the fresh water. In the heat exchanger system, seawater is pumped from the sea, through a sea chest and strainer, to the heat exchanger, and overboard. In the keel cooling system, fresh water is circulated to the keel cooler, which is in direct contact with the seawater. The radiator and fan cooling system uses a stream of air that passes through the radiator to cool the fresh water.

In our discussion of engine cooling systems, we identified the need for freshwater treatment and use of the five corrosion-inhibitor treatments approved for naval service: (1) sodium chromate-disodium phosphate, (2) soluble oil, (3) NAL-COOL 2000, (4) inhibited antifreeze, and (5) MIL-A-53009. These chemicals present health hazards when they come in contact with the skin or eyes or are taken internally. If you are uncertain as to the design of the closed cooling systems we have discussed or the various required freshwater treatments, you should reread this chapter before continuing to chapter 8.