To provide generic, one-of-a-kind active DHW systems for the military, systems utilizing uninhibited propylene glycol without fluid maintenance were desired. An uninhibited propylene glycol was artificially degraded, and corrosion, toxicity, and freeze characteristics were evaluated. These results show that, in a copper system, the fluid remains noncorrosive and nontoxic. Additionally, freeze characteristics remain essentially unchanged. Thus it is shown that uninhibited propylene glycol, despite degradation, is a suitable fluid for use in active solar DHW systems with little or no fluid maintenance.

Units: Dual