Fig. 5 Vertical cooler-dryer (Sprout, Waldron & Company) (b) Fig. 5 Vertical cooler-dryer (Sprout, Waldron & Company) (c) 15. Fig. 6 Horizontal cooler-dryer (Sprout, Waldron & Company) Production of pellets of 4 mm or more in diameter proceeds at a higher rate than when feed is compressed into a smaller diameter.