Mining fan exhaust.
As any Jothrom saleswoman will tell you, when the effluent hits the fan, you really do want that fan to be built by Jothrom. Initially both Bretag and Grelfarl used their own fans, built on site, but the Jothrom model is so superior, they abandoned their own designs.
Since then the fans have been widely adopted across Liberty and can be seen working on foundries, factories, and workshops. Indeed they have even been seen on some of the rougher bars.