Principles of naval engineering - Historic Naval Ships Association

Chapter 19. -REFRIGERATION AND AIR CONDITIONING PLANTSVentilation is accomplished chiefly by meansof fans which supply and exhaust through ventilationduct systems. Most fans used in ductsystems are of the axial-flow type, but somecentrifugal fans are used. Bracket fans are usedto provide local circulation in certain spaces.Portable fans are used for such purposes astemporary ventilation of compartments afterpainting, exhausting toxic gases from closedspaces and tanks, and cooling hot areas aroundmachinery while repairs are being made.SAFETY PRECAUTIONSRefrigerants are furnished in cylinders foruse in shipboard refrigeration and air conditioningsystems. The following precautions must beobserved by personnel handling, using, and storingthese cylinders:1. Never drop cylinders nor permit them tostrike each other violently.2. Never use a lifting magnet or a sling(rope or chain) when handling cylinders. A cranemay be used if a safe cradle or platform isprovided to hold the cylinders.3. Caps provided for valve protection mustbe kept on cylinders except when the cylindersare being used.4. Whenever refrigerant is discharged froma cylinder, the cylinder should be weighedimmediately and the weight of the refrigerantremaining in the cylinder should be recorded.5. Never attempt to mix gases in a cylinder.6. NEVER put the wrong refrigerant into arefrigeration system! No refrigerant except theone for which the system was designed shouldever be introduced into the system. In somecases, putting the wrong refrigerant into a systemmay cause a violent explosion.7. When a cylinder has been emptied, closethe cylinder valve immediately to prevent theentrance of air, moisture, or dirt. Also, be sureto replace the valve protection cap.8. Never use cylinders for any purpose otherthan their intended purpose. DO NOT use themas rollers, supports, etc.9. DO NOT tamper with the safety devicesin the valves or cylinders.10. Open cylinder valves slowly. Never usewrenches or other tools except those providedby the manufacturer.11. Make sure that the threads on regulatorsor other connections are the same as those onthe cylinder valve outlets. Never force connectionsthat do not fit.12. Regulators and pressure gages providedfor use with a particular gas mustNOT be used on cylinders containing othergases.13. Never attempt to repair or alter cylindersor valves.14. Never fill R-12 cylinders beyond 80percent of capacity.15. Whenever possible, store cylinders in acool, dry place, in an upright position. If thecylinders are exposed to excessive heat, adangerous increase in pressure will occur. Ifcylinders must be stored in the open, take carethat they are protected against extremes ofweather. NEVER allow a cylinder to be subjectedto a temperature above 125° F.16. NEVER allow R-12 to come in contactwith a flame or red-hot metal! When exposedto excessively high temperatures, R-12 breaksdown into PHOSGENE gas, an extremely poisonoussubstance. Because R-12 is such apowerfulfreezing agent that even a very small amountcan freeze the delicate tissues of the eyes,causing permanent damage; it is essential thatgoggles be worn by all personnel who may beexposed to a refrigerant, particularly in itsliquid form. If refrigerant does get in the eyes,the person suffering the injury should receivemedical treatment immediately in order to avoidpermanent damage to the eyes. In the meantime,put drops of clean olive oil, mineral oil, orother nonirritating oil in the eyes, and makesure that the person does not rub his eyes.CAUTION: Do not use anything except clean,nonirritating oil for this type of eye injury.(NOTE: If large leaks are indicated, the soapmethod should be used to detect leaks; forminute leaks, the halide torch should be employed.)If R-12 comes in contact with the skin, itmay cause frostbite. This injury should betreated as any other case of frostbite. Immersethe affected part in a warm bath for about 10minutes, then dry carefully. DO NOT rub ormassage the affected area.R-12 is considered a fluid of low toxicity.However, in closed spaces, high concentrationsdisplace the oxygen in the air and thus do notsustain life. If a person should be overcomeby R-12 remove him IMMEDIATELY to a wellventilatedplace and get medical attention at theearliest opportunity. Watch his breathing. Ifthe person is not breathing, give artificialrespiration.491