5-22. Four cubic feet of a gas at 40°F has a gauge pressure of 100 psig. If the volume of the gas is expanded to 6 cubic feet and the gas heated to a temperature of 90°F, what will the new gauge pressure  be? 1. 67.9 psig 2. 69.4 psig 3. 71.5 psig 4. 73.6 psig Learning  Objective: Recognize characteristics  of  gases  used  in pneumatic  systems,  safety precautions  for  handling compressed gas,   and  color  codes of compressed gas cylinders. 5-23. In  addition  to  being  nonpoisonous and free from any acids that might  cause  system  corrosion,  the gas used as the fluid medium for a  pneumatic  system  must  possess which  of  the  following characteristics? 1. Nonflammability 2. Chemical  stability 3. Ready  availability 4. All of the above 5-24. The  gases  used  in  Navy  pneumatic systems are similar to the liquids  used  in  hydraulic systems,    except that the gases are not 1. acid free 2. nontoxic 3. good  lubricants 4. chemically  stable 5-25. What  characteristic  of  compressed air makes it undesirable as a medium  for  pneumatic  systems? 1. Its toxicity 2. Its  flammability 3. Its  moisture  content 4. Its  lubricating  qualities 5-26. In all compressed air systems, the compressor, due to the unlimited supply of air, is installed  in  the  distribution lines leading to the device to be operated. 5-27. Which  of  the  following  statements is NOT true of LP air systems? 1. The LP air system is supplied with LP air by LP air compressors 2. The LP air system is supplied with air by the HP air system supplying  air  through  a pressure-reducing   station 3. The LP air system is supplied with air by the MP air system supplying  air  through  a pressure-reducing   station 4. LP compressed air is used in the  production  of  nitrogen 5-28. Why is the use of nitrogen preferred over the use of compressed  air  in  many  aircraft and  missile  pneumatic  systems? 1. Nitrogen  cannot  support living  organisms 2. Nitrogen  cannot  support combustion  and  fire 3. Nitrogen  does  not  cause  rust or decay of the surfaces with which it comes in contact 4. All of the above 5-29. Which  of  the  following  steps  can a maintenance person take to control  contamination  of pneumatic  systems? 1. Install an air filter in the supply line 2. Keep all tools and the work air clean and dirt free 3. Cap or plug all lines and fittings  immediately  after disconnecting  them 4. Both 2 and 3 above 5-30. You must NEVER use the contents of a cylinder identified by which of the following color codes for purging an oxygen system? 1. Gray 2. Black 3. One black stripe around its top 4. One green stripe around its top 1. True 2. False 34