2, 337, (49 DUO-SEAL VACUUM PUMPS are designed to fit almost every application better and at less cost , ... in the laboratory, industry and school. Ten different models to choose from . . . capacities from 21 to 1400 liters per minute . . . ultimate pressures from 2xl0-2mm ... For complete specifications and prices, ask for Duo-Seal Catalog THE WELCH SCIENTIFIC COMPANY foremost manufacturer* atanbsp;...