Chapter 17. -COMPRESSED AIR PLANTS 



of liquid and ready to repeat the cycle which takes 

 place twice in each revolution. 



A small amount of seal water must be con- 

 stantly supplied to the compressor to make up 

 for that which is carried over with the compres- 

 sed air. The water which is carried over with 

 the compressed air is removed in a refrigera- 

 tion-type dehydrator. 



AIR COMPRESSOR MAINTENANCE 



Minimum requirements for the performance 

 of inspections and maintenance on high pressure 

 air plants are shown on the maintenance index 

 page figure 17-12. 



It is the responsibility of the engineer offi- 

 cer to determine if the condition of the equip- 

 ment, hours of service, or operating conditions 

 necessitate more frequent inspections and tests. 

 Details for outline tests and inspections may be 

 obtained from the appropriate manufacturer's 

 instruction book or from the Naval Ships Tech- 

 nical Manual. 



SAFETY PRECAUTIONS 



There are many hazards associated with the 

 process of air compression. Serious explosions 

 have occurred in high pressure air systems 



because of a diesel effect. 2 Ignition tempera- 

 tures may result from rapid pressurization 

 of a low pressure dead end portion of the 

 piping system, malfunctioning of compressor 

 aftercoolers, leaky or dirty valves, and many 

 other causes. Every precaution must be taken to 

 have only clean, dry air at the compressor inlet. 



Air compressor accidents have also been 

 caused by improper maintenance procedures 

 such as disconnecting parts while they are 

 under pressure, replacing parts with units 

 designed for lower pressures, and installing 

 stop valves or check valves in improper lo- 

 cations. Improper operating procedures have 

 also caused air compressor accidents, with 

 resulting serious injury to personnel and 

 damage to equipment. 



In order to minimize the hazards inherent 

 in the process of compression and in the use 

 of compressed air, all safety precautions 

 outlined in the manufacturers' technical ma- 

 nual and in the Naval Ships Technical Ma- 

 nual must be strictly observed. 



2 A diesel engine operates bytakinginair, compress- 

 ing it, and then injecting fuel into the cylinders, where 

 the fuel is ignited by the heat of compression. The 

 same effect (normally called the diesel effect ) can 

 occur in hydropneumatic machinery and in air, oxygen, 

 or other gas systems, if even a very small amount of 

 "fuel"— a smear of oil, for example, or a single cotton 

 thread— is present to be ignited by the heat of 

 compression. 



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