Welch Variflow can be used for chemical-duty as well as standard-duty operation. The totally dry, DC-drive, variable-speed vacuum pumps  have a two-stage diaphragm mechanism with 45 liters/min flow rate and ultimate vacuum to 1.5 torr (<2 mbar). The chemical-duty Model 8115D-20 uses PTFE heads and diaphragms and FKM valves. The standard-duty Model 8115D-25 uses aluminum heads, EPDM diaphragms and valves.

Welch Pumps, division of Gardner Denver, (847) 676-8800, www.welchvacuum.com