I am trying to find a device that will stop doors slamming in a breeze – fire doors in a factory that slam closed. Do you sell dampers or an approriate soft closing device?

A good quality door closer will do that job.  Please see the link to our heavy duty door closers, and I suggest you look at the Geze TS4000 or the Geze TS2000 BC (back check stops the door slamming open as well as slamming closed, and it’s a standard feature on the TS4000).