Coil safe’s unique self-rinsing ph metal formula removes grease, dirt, and oxidation without harming the environment. Can be diluted with 1 to 5 parts water depending on the condition of the coils or filters.. for evaporator coils. usda authorized. biodegradable . meets epa requirements. non-acid, non-toxic, odorless . can be used on metals and plastic. contains corrosion inhibitors.