Pure R-12 (CC 1425F425) is colorless. It is odorless in concentrations of less than 20 percent by volume in air. In higher concentrations, its odor resembles that of carbon tetrachloride. It has a boiling point of -21F at atmospheric pressure. At ordinary temperatures under a pressure of approximately 70 psig to 75 psig, R-12 is a

Figure 10-12.-Compound R-12 pressure gauge.

liquid. Because of R-12's low boiling point at atmospheric pressure, you must always protect your eyes from contact with liquid R-12; the liquid will freeze the tissues of the eyes. Always wear goggles if you are to be exposed to R-12. R-22 (CHClF425) and R-11 (CC1435F) are colorless, nonexplosive, nonpoisonous refrigerants with many properties similar to those of R-12. Because of the similarities between R-22, R-11, and R-12, only R-12 is discussed.

Mixtures of R-12 vapor and air, in all proportions, will not irritate your eyes, nose, throat, or lungs. The refrigerant will not contaminate or poison foods or other supplies with which it may come in contact. The vapor is nonpoisonous. However, if R-12 concentration becomes excessive, it can cause you to become unconscious or cause death because of lack of oxygen to the brain.

R-12 is nonflammable and nonexplosive in either a liquid or vapor state. R-12 will not corrode the metals commonly used in refrigerating systems.

R-12 is a stable compound capable of undergoing the physical changes required of it in refrigeration service without decomposing. It is an excellent solvent and has the ability to loosen and remove all particles of dirt, scale, and oil with which it comes in contact within a refrigerating system.

HALOCARBONS

HaloCarbons are organic chemical compounds containing hydrogen and one or more atoms of carbon, fluorine, bromine, chlorine, or iodine. These elements may be present in various combinations in the compound.

WARNING

Refrigerants are halocarbons. Personnel working with refrigerants may be injured or killed if proper precautions are not taken.

You may be more familiar with the brand names of halocarbons, such as Freon(s) (refrigerants), Gentron, Gension D., Frigen, AFFF, or Carbon Tetrachloride. You will work with these compounds regularly aboard ship. Because you use them frequently, you gain a false sense of security that makes you forget their potential for danger. Halocarbons are especially dangerous when used in high concentration in confined or poorly ventilated spaces.

PERSONAL SAFETY PRECAUTIONS

R-12 is a powerful freezing agent. Even a very small amount can freeze the delicate tissues of the eye, causing permanent damage. All personnel must wear goggles when working in spaces were they maybe exposed to a refrigerant, particularly in its liquid form. If refrigerant does get into someone's eyes, get that person IMMEDIATE medical treatment to avoid permanent damage. In the meantime, put drops of clean olive oil, mineral oil, or other nonirritating oil in the eyes. Make sure that the person does not rub his/her eyes.

CAUTION

Do NOT use anything except clean, nonirritating oil for this type of eye injury.

If R- 12 comes in contact with the skin, it may cause frostbite. This injury should be treated as any other cause of frostbite. Immerse the affected part in a warm bath for about 10 minutes, then dry carefully. Do not rub or massage the affected area.

Know, understand, and use these safety precautions, and you can safely operate and maintain refrigeration plants.

HANDLING OF REFRIGERANT CYLINDERS (BOTTLES)

Refrigerants are furnished in cylinders for use in shipboard refrigeration systems. The following precautions MUST BE OBSERVED in the handling, use, and storage of these cylinders:

NOTE: Before handling refrigerant bottles, read OPNAVINST 5100.19.

1. NEVER drop cylinders nor permit them to strike each other violently.

2. NEVER use a lifting magnet or a sling (rope or chain) when you handle cylinders. A crane maybe used if a safe cradle or platform is provided to hold the cylinders.

3. Keep the caps provided for valve protection on cylinders except when the cylinders are being used.

4. When refrigerant is discharged from a cylinder, weigh the cylinder immediately. Record the weight of the refrigerant remaining in the cylinder.

5. NEVER attempt to mix gases in a cylinder.

6. NEVER PUT THE WRONG REFRIGERANT INTO A REFRIGERATION SYSTEM! N O REFRIGERANT EXCEPT THE ONE FOR WHICH A SYSTEM WAS DESIGNED SHOULD EVER BE INTRODUCED INTO THE SYSTEM. Check the equipment nameplate or the manufacturer's technical manual to determine the proper refrigerant type and charge. Putting the wrong refrigerant into a system may cause a violent explosion.

7. When a cylinder is empty, close the cylinder valve immediately to prevent the entrance of air, moisture, or dirt. Also, replace the valve protection cap.

8. NEVER use cylinders for other than their intended purpose. Do NOT use them as rollers and supports.

9. Do NOT tamper with the safety devices in the valves or cylinders.

10. Open cylinder valves slowly. NEVER use wrenches or other tools except those provided by the manufacturer.

11. Be sure the threads on regulators or other connections are the same as those on the cylinder valve outlets. NEVER force connections that do not fit.

12. Regulators and pressure gauges provided for use with a particular gas must NOT be used on cylinders containing other gases.

13. NEVER attempt to repair or alter cylinders or valves.

14. NEVER fill R-12 cylinders beyond 85 percent capacity.

15. Store cylinders in a cool, dry place, in an UPRIGHT position. If the cylinders are exposed to excessive heat, a dangerous increase in pressure will occur. If cylinders must be stored in the open, protect them against extremes of weather. NEVER store a cylinder in an area where the temperature will be above 125F.

16. NEVER ALLOW R-12 TO COME IN CONTACT WITH A FLAME OR RED-HOT METAL! When exposed to excessively high temperatures, R-12 breaks down into phosgene gas, an extremely poisonous substance.