Longwave systems just don't work well for this application, although some try using a 10.8 micron filter. The two currently produced systems that are being used at this time (FLIR and Mikron) are both broad band systems that are filtered to the midwave (formerly called 'short') band (3.9 microns). The results are very good, as you can see from this image taken by one of our customers of their coal-fired boiler. Getting temperatures can be challenging however. People are also using still older Agema and Inframetrics midwave cameras.
There are a number of folks doing this sort of work, hopefully some will respond here. What exactly are your needs?
Thermally Yours,
John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820