UL1685 Vertical-Tray Fire Propagation Smoke Release Test Equipment for Electrical Fiber Optic Cables SL-7601S The SL-7601S is a full-scale fire test system that evaluates the vertical flame propagation and smoke release performance of electrical and optical-fiber cables in compliance with UL 1685-2018 — Standard for Vertical-Tray Fire-Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables. Application Scope Determines vertical flame propagation and smoke