Miller Coolmate 4 is a recirculating coolant system for water-cooled GTAW torches and GMAW guns rated up to 600 amperes. It has a 4-gallon (15 L) coolant tank capacity and a maximum cooling capacity of 15,000 BTU/hr at 1.3 gt/min (1.2 L/min). The unit can be used with distilled or deionized water or with Miller coolants, which protect to -37° F (-38°C) and resist algae growth. The Coolmate 4 has a 115-volt, 5.2-ampere, 50/60 Hz, single-phase input power and is equipped with safety features such as a relief valve, coolant filter, and radiator fins to prevent overheating.