OPERATION OF LEERS1

The muffle and open types of leers are compared. The latter has the following advantages: (1) More uniform temps. in the annealing chamber; (2) prevents ingress of cold air beside pans and thus avoids consequent cracking of the ware; (3) better control of temp. and greater reliability of pyrometric indications; (4) less fuel per gross of ware. Size of leers: Leers 8 ft. wide and 65 ft. from center to center of sprockets are recommended for the average glass. Leer chains: Chains having a working strain of 5800 Ibs. at 200 ft. per minute are recommended. In the discussion, L. H. Adams points out that the exact annealing schedule required for any glass can be computed from the annealing constants of the glass which are known or can be determined in the laboratory.