1.1This practice² covers procedures and equipment that will permit, within certain limits, representative sampling for the automated determination of gas concentrations of effluent gas streams. The application is limited to the determination of oxygen (O₂), carbon dioxide (CO₂), carbon monoxide (CO), sulfur dioxide (SO₂), nitric oxide (NO), nitrogen dioxide (NO₂) and total oxides of nitrogen (NO_x).

1.2Velocity measurements are required to determine the mass flow rates of gases. This is not included in this practice.

1.3There are some combustion processes and situations that may limit the applicability of this practice. Where such conditions exist, caution and competent technical judgment are required, especially when dealing with any of the following:

1.3.1Corrosive or highly reactive components,

1.3.2High vacuum, high pressure, or high temperature gas streams,

1.3.3Wet flue gases,

1.3.4Fluctuations in velocity, temperature, or concentration due to uncontrollable variation in the process,

1.3.5Gas stratification due to the non-mixing of gas streams,

1.3.6Measurements made using environmental control devices, and

1.3.7Low levels of gas concentrations.

1.4This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For more specific safety precautions, refer to 5.1.4.8, 5.2.1.6, and 6.2.2.1.