Zero Air Material for Acid Rain CEMS Reporting

Air Liquide (France) has introduced Scott™ brand 72.2 Certified ZAM™ zero air material to meet 40 CFR Part 75 regulations which call for a CEM system to be exposed to "zero air material" during testing protocols in order to qualify the accuracy of the instrument. Part 75.21 states that calibration gases used for this purpose must meet the definitions of 40 CFR Part 72.2. Paragraph (1) of Part 72.2 states: A calibration gas certified by the gas vendor not to contain concentrations of SO2, NOx, or total hydrocarbons above 0.1 parts per million (ppm), a concentration of CO above 1 ppm, or a concentration of CO2 above 400 ppm.

Some CEMS users mistakenly use a standard EPA protocol mixture as a zero gas, thinking this will satisfy the EPA's Acid Rain requirement. But does it really? Not so much. It's a practice that can result in inaccurate CEMS calibration due to biased zero readings arising from contamination in the mixture.

Air Liquide solves this problem, while achieving a balance between regulatory compliance certainty and cost-effectiveness, by offering three types of zero air materials that are guaranteed to be Part 75 compliant; 72.2 Certified ZAM Air , 72.2 Certified ZAM Nitrogen and 72.2 Certified ZAM RATA. Class™ Oxygen EPA Protocol

Each ZAM product is analysed and certified to meet paragraph (1) for trace SO2, NOx, THC, CO and CO2. By using these certified zero products, the risk of faulty calibration due to biased zero readings is eliminated. Scott brand 72.2 Certified ZAM air is engineered to meet or exceed regulatory requirements of condition paragraph (1). Scott Certified ZAM nitrogen is useful in that some CEMS users prefer to use nitrogen to zero their instruments. In this case however, the nitrogen still must meet the impurity requirements of "zero air material."