Pressurized baghouses (PB) are frequently used in large systems for controlling particulate discharges. Preliminary tests indicate that there is striation of the gas streams in baghouse cells, so some equipment failures may not be registered by continuous opacity monitoring (COM) equipment. Reliable monitoring depends on a representative gas stream passing the COM beam, but significant equipment failure can exist with discharge opacity less than 3%. Many existing systems could be modified to provide gas blending. Equipment exists which can detect particulate loading far below the 3% opacity level, but this equipment does not relate directly to opacity. Parameters necessary for a successful COM installation in a PB are: the gas stream must be blended; the COM beam must not exceed 100 feet; the COM output must be expanded so that 3% opacity covers a reasonable portion of the scale; path-length corrections should be permitted only where there is a difference in measured path length and discharge path length; and the COM beam should not be affected by external climatic effects.

"Contract no. 68-01-4146." "March 1981." "EPA-905/2-81/001." Microfiche.