UL910 NFPA262 Steiner Tunnel Flame Test Furnace for Cable Flame Spread Smoke Density SL-910 The SL-910 Steiner horizontal tunnel furnace is a dedicated combustion test system for evaluating the flame spread and smoke density of electrical and optical-fiber cables in accordance with UL 910 / NFPA 262 standards. This integrated system combines ignition sequencing, combustion safety, electrical interlocking, automatic temperature control, manual adjustment, monitoring & alarm