Sigma Scientific Glass Pvt. Ltd manufactures Reducers. Sigma Scientific Glass Pvt. Ltd is an ISO 9001:2000 certified company. Reducers are used in chemical, pharmaceutical, dyes and allied industries. These are basically two types, concentric and eccentric. Concentric reducers are used in vertical installations. Eccentric reducers are used in horizontal pipelines where there is change of bore to enable complete drainage of material without any hold up.