Patent ID: 7901824

Claim:
A heat transfer system, comprising a circulation loop defining a flow path for a colored heat transfer fluid having a conductivity of less than 10 μS/cm, and an ion exchange resin positioned in the flow path, the ion exchange resin comprising at least 15% by total number of the exchangeable groups comprising a colorant, based on the total number of the exchangeable groups, wherein the colorant is of the formula: R{A k [(B) n R 1 ] m } x wherein R is an organic chromophore selected from the group consisting of anthraquinone, triphenylmethane, diphenylmethane, azo containing compounds, disazo containing compounds, trisazo containing compounds, diazo containing compounds, xanthene, acridine, indene, phthalocyanine, azaannulene, nitroso, nitro, diarylmethane, triarylmethane, methine, indamine, azine, oxazine, thiazine, quinoline, indigoid, indophenol, lactone, aminoketone, hydroxyketone, stilbene, thiazole, one or more conjugated aromatic groups, one or more conjugated heterocyclic groups, one or more C-C double bonds, or combinations thereof; A is a linking moiety in said chromophore and is selected from the group consisting of O, N or S; k is 0 or 1; B is selected from the group consisting of one or more alkyleneoxy or alkoxy groups containing from 1 to 8 carbon atoms; n is an interger of from 1 to 100; m is 1 or 2; x is an integer of from 1 to 5; and R 1 is selected from the group consisting of H, C 1 -C 6 alkyl or alkoxy groups containing from 1 to 8 carbon atoms, or combinations thereof.