Unlike the liquid-type transformers that are dependent on other materials such as oil and fire to function, a dry transformer works through voltage changing. So, when dealing with these types of transformers it’s the air that gets cooled and not the liquid as with other types. You simply have to place the dry transformer in a well-ventilated room for the coils to cool with ease.
When using a dry type of transformer, you don’t have to keep it inside fire-resistant vaults or catch basins as you would do with conventional liquid transformers. Also, they do not release any harmful gases, hence environmentally friendly, even for indoor installation.