TM 10-6640-238-13 2-56 (7) Apply several drops of water from aluminum dish to refractometer (4) window.  Close cover and through eyepiece observe location of shadow line in viewer.  Using plastic adjusting rod contained in refractometers base, adjust setscrew located in base so that shadow line intersects zero line of scale (see Detail A-1). Refractometer is now correctly zeroed. (8) Clean refractometer (4) cover and window. (9) Carefully rotate separatory funnel (1) drain cock so that a trickle of fluid can be collected in clean dry aluminum dish.  Two to three drops is sufficient. (10)   Open cover of refractometer (4) window and transfer fluid from aluminum dish to refractometer window. Close cover and observe position of shadow line. Detail A-2 shows a typical test result for JP-4 fuel treated with anti-icing additive at 0-.1% v. test run may show differently as fuel may have different % v. of additive, but readings will be accurate and reflect fuel condition. (11)   Properly dispose of liquids.  Wash apparatus with soap and water and dry thoroughly. (12)   Report out of specification results at once. c. Freezer, Ice-Cube Maker Operation (See COTS Manual with Freezer).  The ice maker is a plug-in unit powered by a hermetically sealed condensing unit. (1) Ice Maker Setup and Operation. (a) Apply power to ice maker by placing circuit breaker A1CB8 (19, figure 2-2), to ON position. (b) Allow unit to operate 4 to 6 hours then load interior with water filled ice cube trays. (c) When ice cube trays are frozen, cubes may be stored in area below shelves of freezing compartment. (d) If required, adjust cold control for proper operating temperatures. (2) Defrosting Ice Maker. (a) Remove power from unit by placing circuit breaker A1CB8 (19, figure 2-2) to OFF position. (b) Open door until accumulated ice has melted and drained from cabinet. (c) Place several pans of hot water in freezing compartment to accelerate melting. (d) Wipe interior completely dry. (e) Apply power to ice maker and allow unit to operate for at least 1 hour before replacing water-filled ice cube trays. 2-8. PREPARATION FOR MOVEMENT. The following paragraphs are used to prepare Mod Lab A for movement. a. Interior.  Prepare as follows: (1) Place all chemicals in designated storage.  Refer to Appendix C.  Ensure all caps are tight. (2) Place all loose test equipment, support equipment, and supplies in their designated storage. (3) Drain and clean the following equipment: (a) RVP Bath (b) Gum Bath (c) Oxidation Stabilization Bath (d) Electric Still