ENGINEERING MATERIAL SPECIFICATIONDate Action Revisions 2004 09 17 Revised Para 3.0 inserted; para 3.1, 3.2, 3.3, 3.13 back force (Ft) is to be measured at 24, 48, 96, 168 and every 168 hours thereafter until 1,000 hours has been reached. All measurements are to be made when fixture has cooled to 23 +/- 2 C. Ft/Fo x 100, min % Retained of Original Value 24 h, 50 48 h, 40 96 h, 40 168 h, 40 336 h, 35 504 h, 35 672 h, 30 840 h, 30 1,008 h, 25 5.3 RECYCLING CODE FKM