Eccentric pipe reducers are used to force air directionally and keep it from getting trapped inside pipes. Eccentric reducers are also known as bell reducers. They can be used to join different sizes of pipe together. They are designed to join pipes at an angled offset so that pipes joined are not in line with each other. Eccentric reducers are always installed with the straight side facing up.
. This website offers illustrations of various pipe reducers http://www.b2bfreezone.com/product-search/eccentric-pipe-reducer.htm .