| abstract |
An aqueous hydraulic fluid composition is described which comprises (i) a salt of formic acid, and (ii) one or more lubricants such as a monovalent metal salt, ammonium, or amine salt of a dicarboxylic acid, in which the Aqueous hydraulic fluid composition demonstrates greater thermal stability when exposed to elevated temperatures for a prolonged period of time and can simultaneously tolerate the presence of synthetic seawater 10% v / v. The aqueous hydraulic fluid composition contains less than about 20% by weight (preferably nothing or practically nothing) of an oil selected from the group consisting of mineral oils, synthetic hydrocarbon oils, and mixtures thereof. Preferably, the hydraulic fluid does not contain glycols in some embodiments. The pH of the hydraulic fluid preferably ranges from 8 to 10 and is maintained by a regulator that preferably comprises borax in some embodiments. |