Flame-retardant composition and process for a flexible open-cell polyurethane foam

A resulting polyurethane foam produced by a flame retardant process comprising reacting:

• (a) at least one polyoxyalkylene polyether polyol,
• (b) at least one organic polyisocyanate, and
• (c) at least one foaming agent comprising:
• (i) at least one blowing agent, wherein said blowing agent comprises a primary blowing agent,
• (ii) at least one surface active agent, and
• (iii) at least one catalyst,
• and in the further presence of:
• (d) at least one flame retardant agent comprising:
• (i) expandable graphite,
• (ii) at least one ammonium polyphosphate, and
• (iii) at least one organophosphorus flame retardant,
• wherein said resulting polyurethane foam is used for cushioning application materials and wherein the surface flammability of said resulting polyurethane foam does not exhibit any flaming running or flaming dripping, wherein flame spread index of said resulting polyurethane foam is less than or equal to 25 during testing of said resulting polyurethane foam in accordance with ASTM D 3675, wherein specific optical density of smoke value of said resulting polyurethane foam is less than or equal to 100 under flaming mode and non-flaming mode at 1.5 minutes during testing of said resulting polyurethane foam in accordance with ASTM E 662, and wherein specific optical density of smoke value of said resulting polyurethane foam is less than or equal to 175 under flaming mode and non-flaming mode at 4.0 minutes during testing of said resulting polyurethane foam in accordance with ASTM E 662, in satisfaction of fire performance criteria of the Federal Railroad Administration, Federal Transit Administration, and National Fire Protection Association.