Flammability, Smoke Emission  & Toxicity
The following excerpt is a generic set of flammability criteria intended for passenger transit rail vehicle specifications. The requirements are based on a combined set of criteria from NFPA 130 - 2014, the current 49 CFR 238.103, and Appendix B to Part 238, and industry informal standards such as Boeing BSS-7239, and Bombardier Transportation SMP 800-C.


All materials used in the vehicle shall comply with the flammability; smoke emission, toxic gas, and fire retardation requirements specified herein.

Materials used in the construction of the vehicle shall meet the requirements contained in this section, 49 CFR 238.103, Appendix B to Part 238, and NFPA 130 - 2023.

Should a conflict exist between the NFPA and Federal requirements and requirements listed elsewhere in these provisions, the more restrictive shall govern. Note: the FRP smoke requirement has been modified to a more restrictive value to improve smoke characteristics for tunnel operation. (For ASTM E662 to exclude polyester resin FRP, use the following: Ds (1.5) ≤ 100, Ds (4.0) ≤ 165)

Materials used in the construction of the vehicle shall be selected to minimize the total combustible material content of the vehicle.

The Contractor shall furnish a comprehensive listing of materials used in the vehicles in matrix form (flammability matrix). The flammability matrix shall include the following information as a minimum for every unique material:
  • Material application (usage, component description, part/drawing number, and location)
  • Material supplier (full name of material original manufacturer)
  • Material description (actual material common name and trade name) Material unique identifier (e.g. part number, formula number, compound number, etc.)
  • Material weight (both density, unit weight and total weight in vehicle)
  • Flammability data as applicable:
    • Flame spread / flammability
    • Smoke generation (both flaming and non-flaming)
    • Heat value per pound
    • Heat release rate
    • Total heat released
    • Flashpoint / autoignition temperature
    • Toxic content in combustion products
  • Testing laboratory (full name of independent testing entity for each test report)
  • Test report number and date (for each test result listed)
  • Submittal letter (letter number(s) submitting test reports and material specifications)
  • Response Letter (letter(s) dispositioning the latest submission of data)
  • Approval status (current approval status of the specific material)
The Contractor shall submit the original, signed, laboratory test results for all materials, for all tests specified, including a technical data sheet, for approval, (modified test reports are not accepted). The flammability matrix shall contain sufficient information to positively identify each material listed [CDRL Requirement]. The test report electronic files shall be named with the test report number, and type of test.

The material description used by the contractor shall be identical in every place it appears; test report documentation, technical data sheet, drawings, bill of materials, flammability matrix, and other related references. This documentation must be directly traceable between the technical documentation, test reports and flammability matrix, to the applicable Contractor drawings without ambiguity.

Copies of prior test results showing that proposed materials have complied with the specified standards and tests may be submitted for approval if the test reports are no more than five (5) years old. Assurance from the original material manufacturer may be required to verify that the material presently considered for use is the same composition as that previously tested.

Flammability And Smoke Generation Criteria

Materials used in the construction of the vehicle shall meet the material test requirements of NFPA 130 - 2023, section 8. Combustible material items that are intended for limited use, and limited weight, in the vehicle, that are unable to meet the criteria in NFPA 130, table 8.4.1 must be appropriately mitigated with a Fire Hazard Analysis (FHA) per NFPA 130, section 8.4.2. Please note that all combustibility data as defined in this chapter is required to be provided and the material included in the FST Matrix and FHA.

The current table from NFPA 130-2023 is copied below for reference


Category Function of Material
(see comments)		 Test Procedure Performance Criteria
Cushioning All individual flexible cushioning materials used in seat cushions,
mattresses, mattress pads, armrests, crash pads, and grab rail paddinga-e 		ASTM D 3675
 Is ≤ 25
ASTM E 662 Ds (1.5) ≤ 100, Ds (4.0) ≤ 200
(to exclude polyester resin FRP, use the following: Ds (1.5) ≤ 100,
Ds (4.0) ≤ 165)
Fabrics Seat upholstery, mattress ticking and covers, curtains, draperies,
window shades, and woven seat cushion suspensionsa-c, f-h		 14 CFR 25, Appendix F,
Part I (vertical test)		 Flame time :> 10 sec
Bum length :> 6 in.
ASTM E662 Ds (4.0) ≤ 200
Other vehicle
components		 Seat and mattress frames, wall and ceiling lining and panels, seat and
toilet shrouds, toilet seats, trays and other tables, partitions, shelves,
opaque windscreens, combustible signage, end caps, roof housings,
articulation bellows, exterior shells, nonmetallic skirts, battery case
material, and component boxes and coversa,b,i-k		 ASTM E 162 Is ≤ 35
ASTM E 662 Ds (1.5) ≤ 100, Ds (4.0) ≤ 200
Thermal and Acoustical Insulationa, b ASTM E 162
ASTM E 662		 Is ≤ 25
Ds (4.0) ≤ 100
HVAC Ductinga,b ASTM E 162
ASTM E 662		 Is ≤ 25
Ds (4.0) ≤ 100
Floor Coveringb,k,l
(= 0.5 W/cm^2)		 ASTM E 648
ASTM E 662		 CRF > 0.5 W/cm2 (5kW/m2)
Ds (1.5) ≤ 100, Ds (4.0) ≤ 200
Light diffusers, windows, and transparent plastic windscreensa, b, i ASTM E 162
ASTM E 662 		Is ≤ 100
Ds (1.5) ≤ 100, Ds (4.0) ≤ 200
Adhesives and Sealantsa, b, p
(See new section 8.4.1.16) 		ASTM E 162
ASTM E 662		 Is ≤ 35
Ds (1.5) ≤ 100, Ds (4.0) ≤ 200
Elastomers a,b,i,j Window gaskets, door nosings, intercar diaphragms, seat cushion suspension diaphragms, and roof mats ASTM C 1166
ASTM E 662		 Flame propagation
≤100mm (4.0in)
Ds (1.5) ≤ 100, Ds (4.0) ≤ 200
Wire and Cable All See 8.6. 7.1.1.1 through
8.6. 7.1.3.		 See 8.6.7.1.1.1 through
8.6.7.1.3.
Structural
componentsm 		Flooring,nothero ASTM E 119 Pass


Note: The previous requirement for wiring flammability was per IEEE Std 383 - Flammability. The 2014 NFPA 130 criteria cites a number of sources for wiring flame and smoke performance too numerous to repeat the list here.

Note: More History: The smoke density for the wiring was listed as ASTM Ds (4.0) ≤ 50. This is much less than previous values of ASTM Ds (4.0) ≤ 75(NF) and ASTM Ds (4.0) ≤ 200 (F) used on other prior projects. The overall trend is a general reduction in smoke generation.

Toxic Content Limits In Combustion Products

The maximum toxic gas concentration in the combustion products of any materials used in the construction of the vehicle shall not exceed the following values:


Toxic Gas – Boeing BSS-7239
(or Bombardier SMP 800-C)		 Maximum Concentration
Carbon Monoxide  (CO), 3500 ppm
Hydrogen Fluoride  (HF), 200 ppm
Nitrogen Dioxide  (NO2), 100 ppm
Hydrogen Chloride  (HCL), 500 ppm
Hydrogen Cyanide  (HCN), 150ppm
Sulfur Dioxide  (SO2), 100 ppm