40 CFR § 63.7296
What emission limitations must I meet for battery stacks?
June 9, 2020
You must not discharge to the atmosphere any emissions from any battery stack at a new or existing by-product coke oven battery that exhibit an opacity greater than the applicable limit in paragraphs (a) and (b) of this section.
(a) Daily average of 15 percent opacity for a battery on a normal coking cycle.
(b) Daily average of 20 percent opacity for a battery on batterywide extended coking.