Care and Maintenance of Air System Equipment

Chapter 7—AUXILIARY MACHINERY 5. When the cooling water system of the com- pressor is being refilled, the water inlet valve should be opened slightly to allow the water to rise slowly in the cooler shell and water jackets. Also, the vent valves which are fitted to the water spaces should be opened to permit entrapped air to escape, and thus prevent the formation of air pockets in the system. CARE AND MAINTENANCE OF AIR SYSTEM EQUIPMENT The air flasks and separators of surface ships must be given a surface inspection every 3 months to determine if there is any external corrosion or damage to flasks or piping. Because of the coating of zinc chromate primer, corrosion is seldom a source of trouble on the internal surfaces of air flasks; however, corrosion may take place on the external surfaces of air flasks and may be sufficiently serious to weaken the material, especially in high-pressure flasks. Surface corrosion usually occurs at points which cannot be easily reached for proper cleaning and painting. Drainage of air system equipment must be suf- ficiently frequent to prevent excessive accumula- tions of moisture and oil. Such accumulations not only cause internal corrosion and fouling of moving parts, but also create a serious hazard since any excessive oil accumulation may result in an explosion. All high-pressure flasks and separators must be inspected, cleaned, tested, and repainted at prescribed intervals by a repair activity. For sur- face ships, the initial and subsequent intervals should not exceed 6 years. Although inspection intervals for separator flasks are approximately 3 years, if there is reason to believe that serious corrosion of either the exterior or the interior of air flasks is taking place, before the lapse of the normal interval, the flasks should be inspected and tested at once. Periodic examinations are essential to deter- mine the condition of air system equipment; these examinations should include not only a complete inspection of the interior and the exterior of flasks and separators, but also ultrasonic inspections and hydrostatic tests. After a thorough cleaning, the flasks which successfully pass the hydrostatic test are given the prescribed internal protective coating, and when necessary, the exterior is painted. Further information on the details of the inspections and maintenance performed by repair activities can be found in chapter 551, section VIII, of Naval Ships’ Technical Manual. INSPECTIONS AND TESTS The minimum maintenance requirements for the performance of inspections and tests of com- pressed air plants are given in figure 7-1. It is the responsibility of the engineer officer to determine if the condition of the equipment, hours of service, or operating conditions necessitate more frequent inspections and tests. Details for each test and inspection are obtained from the PMS Manual, or the appropriate manufacturer’s technical manual. SAFETY PRECAUTIONS Competent personnel operating and maintain- ing any machine keep it performing as efficiently as possible. In order to achieve peak performance from a compressed air plant, they take steps to prevent or minimize the occurrence of any con- dition which might reduce plant capacity or result in serious damage. All personnel should take every possible precaution to prevent potential explo- sions, especially when operating high pressure systems. Safety precautions which will aid you in preventing explosions and in maintaining a plant in satisfactory operating condition are listed below. 1. Minimize the possibility of explosions in an air compressor, discharge line, or receiver by taking steps to prevent or eliminate the following: a. Dust-laden intake air. b. Presence of oil vapor in compressor or receiver. c. Leaking or dirty valves. 2. Make sure that the compressor intake receives only cool, dry air. 3. Use only prescribed agents for cleaning compressor intake filters, cylinders, or air passages. DO NOT use benzene, kerosene, or 7-5