TM 10-6640-239-13 4-80 4-36.    AIR FLOW CONTROL DEVICES AND PIPING SYSTEM. This task consists of: a. Remove b. Install c. Test INITIAL SET-UP Tools Required General Mechanics Tool Kit, (Appendix B, Section III, Item 1) Materials/Parts Required Teflon Tape, (Appendix E, Section II, Item 139) General Safety Instructions WARNING ELECTRICAL SHOCK Before  performing  any  maintenance  actions  on  electrical  equipment,  ensure  all electrical power has been turned off.  Failure to comply with this warning may result in serious injury or death. REMOVE NOTE Before removing flow control devices purge by opening any system valve. 1. Remove Flow Control Devices.  See Figure 4-24. Remove laboratory stopcock valves (1) by unscrewing valves from tees or elbows located in the air system mounting to laboratory walls. 2. Remove System Piping.  See Figure 4-25. a. Remove sections of system piping (1) by locating nearest pipe union (2) and threaded pipe fittings. b. Disconnect union (2). c. Disconnect pipe nipple from elbow (3), coupling (4), or valve (5). d. If section of pipe (1) contains brazed joints or unions (2) refer to direct support maintenance. INSTALL 1. Install Flow Control Devices.  See Figure 4-24. a. Apply teflon tape on male fittings.  Be sure to wrap teflon tape in same direction of pipe thread. b. Install stopcock valves (1) by screwing valves into air system piping tees or elbows. 2. Install System Piping.  See Figure 4-25. a. Apply teflon tape on male fittings.  Be sure to wrap teflon tape in same direction of pipe thread. b. Connect pipe nipple to elbow (3), coupling (4) or valve (5). c. Connect pipe to union (1). TEST Test air system in accordance with operating procedures listed in paragraph 2-6k.