Open cell polyurethane flame-retardant foams

A two-component open cell polyurethane spray foam composition comprising:

• an A-side comprising:
• at least one A-side diisocyanate and at least one HFO propellant that comprises trans 1,3,3,3 tetrafluoropropene;
• a B-side comprising:
• B-side reactants comprising at least one aromatic polyol, at least one B-side plasticizer, at least one surfactant, at least three catalysts, water and at least one HFO propellant that comprises trans 1,3,3,3 tetrafluoropropene;
• said at least three catalysts consisting of:
• at least one organo-tin containing catalyst and
• at least one potassium containing catalyst;
• and
• at least one dimorpholino-based ether catalyst, wherein no catalyst other than the at least one organo-tin containing catalyst, the at least one potassium containing catalyst, and the at least one dimorpholino-based ether catalyst are present in the two-component open cell polyurethane spray foam composition;
• a molar ratio of the at least one potassium-containing catalyst to the at least one organo-tin containing catalyst being at least approximately 1.5:1.0;
• the at least one surfactant comprising a polysiloxane polyoxyalkylene block copolymer surfactant;
• the B-side water comprising at least 8 weight percent of said B-side reactants;
• an open cell polyurethane spray foam formed from the two-component open cell polyurethane foam composition has a Class B rating with a flame spread between 25 and 75 inclusive and a smoke developed of under 450 using ASTM E 84 testing protocol;
• the open cell polyurethane spray foam having a density of approximately 1 pcf (pounds per cubic foot) or less;
• the open cell polyurethane spray foam having an R-value of approximately 3.2 or greater;
• and
• an open cell content of at least 90% in the open cell polyurethane spray foam.