Patent ID: 7419618

Claim:
A ready-to-use aqueous fuel cell coolant composition having an initial conductivity of at most 50 μS/cm and which consists essentially of (a) from 10 to 90% by weight of alkylene glycols or derivatives thereof, (b) from 90 to 10% by weight of water, (c) from 0.005 to 5% by weight of an azole derivative, and (d) orthosilicates in an amount to provide the aqueous coolant composition with a silicon content of from 2 to 2000 ppm by weight, wherein the azole derivative consists of one or more five-membered heterocyclic compounds having 2 or 3 heteroatoms selected from the group consisting of nitrogen and sulfur, which contain no or at most one sulfur atom and which may carry a fused aromatic or saturated six-membered ring.