TM 10-6640-215-13 4-39.  REMOVE/INSTALL COMPONENTS OF WATER SYSTEM-continued. c.  Position sink into opening on countertop and snap down into place. d.  Connect union at top of sink trap. TEST Test Water System. Test; Water system in accordance with operating procedures listed in paragraph 2-8b. 4-40.  REMOVE/INSTALL GAS ALARM SYSTEM. This task covers: a. Removal c. Test b. Installation INITIAL SET-UP: Tools Required General Mechanics Tool Kit, (Appendix B, Section III, Item 2) Soldering Gun, (Appendix B, Section III, Item 1) Materials/Parts Required Solder, (Appendix E, Section II, Item 133) Lockwashers, (Appendix F) General Safety Instruction WARNING ELECTRICAL SHOCK Before performing any maintenance actions on electrical equipment, ensure all electrical power has been turned off.  Death or serious injury may occur from failure to do this. REMOVAL 1.  Remove Gas Alarm.  See figure 4-32. a.   Power input cable to laboratory disconnected. b.   Verify no electrical power to the gas alarm.  Pilot light off. c.   Loosen latch and swing open cover door of gas alarm unit. d.   Remove one captive release screw and swing panel out. e.   Carefully remove circuit board. 4-99