Hard water compatible phosphate-containing heat transfer fluids

摘要

A heat transfer fluid is disclosed which comprises a glycol, a phosphate, and a copolymer additive which is a copolymer of an ethylenically substituted carboxylic acid and an aldehyde. A method for preparing the heat transfer fluid comprises admixing 92 to 96 weight percent of one or more glycols; 2 to 4 weight percent of a phosphate; and 0.01 to 0.25 weight percent of the copolymer additive. Precipitation of phosphate salts is inhibited in phosphate-containing glycol-based fluids by the addition of the copolymer additive before mixing the fluid with water.