Tunnel furnace ST-910

for fire resistance testingcombustionnatural convection

The Steiner Tunnel is used to measure flame travel distance and optical density of smoke for insulated, jacketed, or both, electrical wires and cables and optical fiber cables that are to be installed in plenums and other spaces used to transport environmental air without being enclosed in raceways. The National Electrical Code NEC 800 defines the fire ratings for cables, CMP, CMR, CMG, CM, CMX. CMP cables are plenum cables, these cables are used if networking must be done in air ducts. They can be used for commercial or residential spaces. They will not combust and cannot actually cause fires. CMR cables are riser cables. These are used for regular networking from room to room, as long as the cable does not need to pass through an air duct. CM/CMG cables are the most commonly used commercial grade communication cable. CMX is a residential grade cable. Such cables are limited to residential or other small applications where the number of communication cables used is very little. CMP is the strictest cable in the NFPA/UL Fire Standard and the applicable safety standard is NFPA 262 / UL 910. The test provides for multiple specimens to be laid in the horizontal duct of the unit and burned for 20 minutes with an 87.9KW Gas Bunsen burner (300,000 BTU/Hr). The passing standard was that the flame should not extend beyond 5 feet from the front of the gas bunsen burner flame.