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Smoke Density and Surface Flammability Requirements For U.S. Public Transportation Vehicles


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Smoke density and surface flammability fire test requirements of material used in the interior of U.S. public transportation vehicles to include rail passenger cars, transit buses, and transit vans.

There are three widely used documents that describe the required smoke and surface flammability maximums for transit materials:

  • Federal Criteria 49 CFR Part 238
  • Federal Transit Administration Docket 90-A
  • National Fire Protection Association (NFPA) 130

While the documents are substantially the same, there are differences that are significant enough to require the reader to evaluate all standards independently.

For example, the Federal Transit Administration Docket 90-A sets a maximum smoke density of 200 at 4 minutes for foam seating cushions.

The federal rail criteria and NFPA reduces the maximum from 200 down to 175.

Also, the "Product Criteria" listings are expressed differently in each of the three documents.

The SGS Govmark summaries of these requirements are offered as a ready reference.

Surface Flammability & Smoke Density Requirements

Specified By Federal Criteria 49 CFR Part 238

Category Function of Material ASTM E662 ASTM E162
Max Specific Density Max Flame Spread*
90 Seconds 4 Minutes
Cushions, Mattresses All 100 175 25**
Fabrics Seat upholstery, mattress ticking & covers, curtains, draperies, wall coverings, & window shades NR 200 (1)
Other Vehicle Components Seat & mattress frames, wall & ceiling panels, seat & toilet shrouds, tray & other tables, partitions, shelves, opaque windscreens, end caps, roof housings, & component boxes & covers 100 200 35
Flexible cellular foams used in armrests & seat padding 100 175 25**
Thermal & acoustic insulation NR 100 25
HVAC ducting NR 100 35
Floor covering 100 200 (2)
Light diffusers, windows & transparent plastic windscreens 100 200 100
Elastomers Window gaskets, door nosings, inter-car diaphragms, roof mats, & seat springs 100 200 (3)
Structural Components Flooring, Other N/A N/A N/A
  • NR = Not required
  • N/A = Not applicable; Another test applies
  • * In addition, flaming running and/or dripping not permitted
  • ** ASTM D3675
  • (1) FAA 12 Second Vertical: Maximum Afterflame*: 10 seconds; Maximum Burn Length: 6"
  • (2) ASTM E648: Minimum Critical Flux: 0.5 W/cm2
  • (3) ASTM C1166: Maximum Flame Propagation* 4"

Surface Flammability & Smoke Density Requirements

Specified By Federal Transit Administration Docket 90-A

Category Function of Material ASTM E662 ASTM E162
Max Specific Density Max Flame Spread*
90 Seconds 4 Minutes
Seating Cushion 100 20 25**
Frame 100 200 35
Shroud 100 200 35
Upholstery - Coated NR 250 (1)
Upholstery - Uncoated NR 100 (1)
Panels Wall 100 200 35
Ceiling 100 200 35
Partition 100 200 35
Windscreen 100 200 35
HVAC Ducting NR 100 35
Light Diffuser 100 200 100
Flooring Wheel Well & Structural NR NR N/A
Carpeting NR NR (2)
Insulation Thermal NR 100 25
Acoustic NR 100 25
Miscellaneous Firewall NR NR N/A
Exterior Shell 100 200 35
  • NR = Not required
  • N/A = Not applicable; Another test applies
  • * In addition, flaming running and/or dripping not permitted
  • ** ASTM D3675
  • (1) FAA 12 Second Vertical: Maximum Afterflame*: 10 seconds; Maximum Burn Length: 6"
  • (2) ASTM E648: Minimum Critical Flux: 0.5 W/cm2
  • (3) ASTM C1166: Maximum Flame Propagation* 4"

Surface Flammability & Smoke Density Requirements

Specified by NFPA 130

Category Function of Material ASTM E662 ASTM E162
Max Specific Density Max Flame Spread*
90 Seconds 4 Minutes
Cushioning All individual flexible cushioning materials used in seat cushions, mattresses, mattress pads, armrests, crash pads, & grab rail padding 100 175 25**
Fabrics Seat upholstery, mattress ticking & covers, curtains, draperies, window shades, & woven seat cushion suspensions NR 200 (1)
Other Vehicle Components Seat & mattress frames, wall & ceiling lining & panels, seat & toilet shrouds, toilet seats, trays & other tables, partitions, shelves, opaque windscreens, combustible signage, end caps, roof housings, articulation bellows, exterior shells, nonmetallic skirts, & component boxes & covers 100 200 35
Thermal & acoustical insulation NR 100 25
HVAC ducting NR 100 25
Floor covering 100 200 (2)
Light diffusers, windows, & transparent plastic windscreens 100 200 100
Adhesives & sealants 200 200 35
Elastomers Window gaskets, door nosings, inter-car diaphragms, seat cushion suspension diaphragms, & roof mats 100 200 (3)
Wire & Cable All N/A N/A N/A
Structural Components Flooring, Other NR NR N/A
  • NR = Not required
  • N/A = Not applicable; Another test applies
  • * In addition, flaming running and/or dripping not permitted
  • ** ASTM D3675
  • (1) FAA 12 Second Vertical: Maximum Afterflame*: 10 seconds; Maximum Burn Length: 6"
  • (2) ASTM E648: Minimum Critical Flux: 0.5 W/cm2
  • (3) ASTM C1166: Maximum Flame Propagation* 4"