“Face firing” means a furnace firing design in which the burners are mounted in an array on one or more vertical walls, including:

1. (a) Opposed firing, where the burners are mounted on 2 opposite walls; and
2. (b) Single-wall firing, where the burners are mounted on only one wall.

Source. (See Revision Note at chapter heading for Env-A 1300) #9803, eff 10-31-10; ss by #12584, eff 8-15-18 (formerly Env-A 1302.17)