TM 9-2320-209-20-3-2 c. Replacement. FRAME 1 1. 2. 3. 4. 5. GO Using 5/8-inch wrench, screw in and tighten two drain cocks (1). Using 3/4-inch wrench, screw in and tighten two elbows (2) into lower air reservoir (3). Face elbows as noted. Using 6-inch pipe wrench, screw in and tighten elbow (4) into lower air reservoir (3). Face elbow as noted. Using 3/4-inch wrench, screw in and tighten safety valve (5) into elbow (4). Using 3/4-inch wrench, screw in and tighten tee fitting (6) and two elbows (7) into upper air reservoir (8). Face elbows and tee fitting as noted. TO FRAME 2 13-187