Pure Air Generators remove water, oil and dirt from the existing compressed-air supply, eliminating corrosion and damage to pneumatic and analytical instruments. All particulates are removed from the source air and never appear in the air product. It is typical for air monitoring equipment, calibrated to zero with cylinder air which is labeled as zero air, to indicate a greater deflection through zero when connected to a pure air generator, clearly demonstrating the greater purity over cylinder air. In addition, the dew point of the air product in pure air generator will not exceed -60 F, making this the ideal air source. Equally important, the oxygen concentration is a constant 21%, as found in the ambient environment. This again, is in contrast with zero air cylinders where a 6-8% variation in the oxygen concentration is not unusual. This variation has a profound effect when calibration of ozone generators and ozone monitors or total hydrocarbon analyzers is attempted. This oxygen variation effect becomes even more pronounced when multiple instruments and locations are involved. In addition to generating consistently clean air, the pure air generators have effectively eliminated air cylinders and their associated regulators from a great number of laboratories.