Flame Retardant Foam
Flame Retardant Foam is a type of fluid which can be stored in a Coolant Truck, or even be replacing the ammunition in a Vehicular Flamer.
Unlike Cooling Fluid this foam is intended to deal with Inferno fire, and will immediately douse said Inferno flames. It also will help to prevent future fires, as long as the foam isn't cleaned up.
While not intended to be used as Cooling Fluid, Flame Retardant Foam can be used to cool down an overheating unit. While coolant can drop a units heat by 3, foam can only drop the heat by 2 in the Classic BattleTech Heat Scale.