10/19/2026
A Clear Advantage.
Stack Testing 101: How to Decide on EPA Method 1 Port Placement
When was the last time you looked at stack test port placement before construction started?
One of the most common and costly testing issues we see isn't the source test itself, it's discovering that the sampling ports were installed in a location that doesn't meet EPA Method 1 requirements. Fixing the problem after startup can mean added engineering, fabrication costs, schedule delays, and even repeat testing.
EPA Method 1 is designed to ensure representative emissions measurements by locating sampling ports in areas where stack flow is as uniform as possible. The preferred location is generally at least 8 duct diameters downstream and 2 duct diameters upstream from flow disturbances such as bends, fans, dampers, expansions, contractions, or other equipment that can create turbulence.
Before finalizing a stack design, consider:
✅ Locations of elbows, fans, and dampers
✅ Available straight-run duct length
✅ Stack diameter and access requirements
✅ Future source testing and monitoring needs
✅ Platform, ladder, and safety requirements
✅ Potential flow disturbances and cyclonic flow conditions
A few hours spent reviewing Method 1 requirements during design can prevent significant modifications later and help ensure successful compliance testing from day one. EPA guidance specifically notes that Method 1 considerations should be addressed before construction because failing to do so may require later stack alterations or deviations from standard procedures.
At Bison Engineering, we routinely evaluate stack configurations, testing accessibility, and EPA Method 1 compliance during project development to help clients avoid surprises when it's time for performance testing.
