Efficiency is an important topic in mechanical draft fan engineering, as well as process engineering more broadly.
Currently, there are many different types of fan efficiency ratings prevalent in discussions of draft fan engineering, but these ratings are rarely compared side by side and assessed to see if they are relevant to the projects in question.
Projects can be awarded based on superior efficiency ratings without fully understanding the ways in which ratings were derived.
This paper begins to address this issue by explaining each of the ratings commonly used to evaluate mechanical draft fans and providing some working guidelines for assessing fan efficiency.