Water cooling systems for welding operations Miller Coolmate 3. Use: Designed to cool water-cooled welding torches (TIG or MIG), preventing them from overheating during high amperage operation. Capacity: Each unit contains a 3-gallon (approximately 11-liter) reservoir of coolant. Features: Features a closed-loop design with a radiator to reduce fluid temperatures, as well as a paddle wheel flow indicator for easy monitoring.