Steiner Tunnel

  • NFPA 262
  • , UL910
Steiner Tunnel is purposed to determine whether the flame-propagation and smoke-generating characteristics of cables without raceways are within the limits specified in the National Electrical Code (NEC).
UL910 covers the test method for determining values of flame-propagation distance and optical smoke density for electrical and optical-fiber cables that are intended to be installed in ducts, plenums, and other spaces used to transport environmental air without the cables being enclosed in raceways in those spaces.
Cables having adequate fire-resistant and low-smoke-producing characteristics need not comply with general wiring methods when the cables are installed (without raceways) in environmental-air ducts, concealed hollow building spaces used as ducts for environmental air, and other environmental-air-handling spaces not specifically excluded (areas involving grease and flammable dust, vapor, and the like). This test method is essentially the same as the test method described in the Standard Method of Test for Fire and Smoke Characteristics of Wires and Cables, NFPA 262.Steiner Tunnel


  • The furnace is a rectangular horizontal duct with a removable lid.
  • ​The sides and base of the furnace are lined with an insulating firebrick.
  • ​One side of the fire testing furnace is provided with double quartz observation windows with the inside pane flush mounted.
  • ​Multiple windows are located along the furnace so that the entire length of the test sample is observable from outside the fire chamber.
  • ​The lid consisting of a removable noncombustible metal and mineral composite structure.
  • ​The lid covers the fire test chamber and the test samples maintains in an unwrapped and flat condition.
  • ​Two NFP elbow gas burners delivering flames upward against the surface of the test samples.
  • ​Remote spark ignition function, to ensure the safety.
  • ​An air intake shutter is located upstream of the burner.
  • ​Six refractory firebricks along the side walls of the chamber for proper combustion.
  • ​The static pressure meter inserted through the top at the mid-width of the tunnel below the ceiling.
  • ​The exhaust end is fitted with a gradual rectangular-to-round transition piece.
  • ​The exhaust duct is insulated with high temperature mineral composition material.
  • ​An exhaust fan is installed at the end of the exhaust duct.
  • ​The air flow and draft pressure are controlled by automatically damper and frequency converter.
  • ​A photometer system consisting of a lamp and photocell mounted on a horizontal section, and with the light beam directed upward along the vertical axis of the vent pipe.
  • Thermocouples installed inside and outside the floor of the test chamber.
  • ​Data acquisition system and operating software.


  • Model No.: STF
  • Dimensions: Furnace: Approx. 21300mm(W) × 1100mm(H) × 2100mm(D)                                                Control Unit: Approx. 430mm(W) × 370mm(H) × 320mm(D)
  • Weight: Approx. 1,700kg
  • Voltage: AC 230V 50Hz 15A; AC 380V 50Hz 60A
  • User Manual: Available.
  • Gas Supply: Methane as specified in standard
  • Others: Compressed Air (6bar); Crane.

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