Principal Mechanical Engineer... we make industrial Dampers which control gas flow through duct systems..... sometimes with So2/So3 or at temperatures up to 1100degC from big stuff to small stuff.....
Click image for larger version. 

Name:	P9180685.jpg 
Views:	124 
Size:	91.9 KB 
ID:	7172
Click image for larger version. 

Name:	DSCF0043.jpg 
Views:	124 
Size:	91.1 KB 
ID:	7171