The Catholic school and church I went to had one of those Tornado's. I remember they were very loud. When I was in 7th & 8th grade we use to help the janitor clean the church when they decorated for Christmas. Sometimes vacuuming the carpeted alter with it. A few times he would have a black cloth bag attached to the exhaust port on top and other times said no we did not need it. Was there some kind of filter inside them also? Never got to see the inside of one.