PORTACAL® Benzene calibration gas, by Gasco. Benzene (C6H6) is a widely used industrial chemical. Benzene is found in crude oil and is a major part of gasoline. It's used to make plastics, resins, synthetic fibers, rubber lubricants, dyes, detergents, drugs and pesticides. Benzene is produced naturally by volcanoes and forest fires. | Use PORTACAL® Benzene calibration gas to be sure your gas detection instrumentation is functioning properly.