Patent ID: 7910529

Claim:
A composition useful as a fire resistant commercial aviation hydraulic fluid composition comprising (A) at least about 50% by weight of a phosphate ester or mixture of phosphate esters represented by the formula wherein R 1 , R 2 and R 3 are alkyl groups having from 1 to 14 carbon atoms wherein the sum of carbon atoms in R 1 , R 2 and R 3 is in the range of from 9 to 18, and (B) at least about 10% of at least one substituted or unsubstituted, non-phosphate aryl compound, said aryl compound selected from the group consisting of phenyls, biphenyls, terphenyls, furans, thiophenes, benzenes, benzofurans, indanes, pyridines, benzylated toluene/xylene mixture, diphenyl oxides, naphthalene and anthracene and mixtures thereof wherein the substituents on the substituted aryl compounds are selected from the group consisting of alkyl groups having from 1 to about 30 carbon atoms, cycloalkyl, alkoxy and aryloxy groups and mixtures thereof, and wherein said composition exhibits, in combination, a fire point in excess of 177° C., a flash point of at least 160° C. and an autoignition temperature of at least 399° C., a pour point less than −62° C., a viscosity at −54° C. less than 2000 cS, and a viscosity at 98.9° C. greater than 3.0 cS.