This field-test method provides chloride and fluoride concentration results on a dry basis. Concentration data for gaseous chlorides and fluorides are assumed to be hydrochloric acid gas, and hydrofluoric acid gas when calculating mass emission rates.

Mass emission rates of HCl and HF can be calculated if the effluent volumetric flow rate is known. Volumetric flow rates can be calculated by conducting EPA Methods 1-4 or their equivalents.

This field test method provides data having bias and precision for HCl consistent with the values in Section 14. In addition, the test-specific bias can be assessed for each test by conducting the post-test quality assurance check. The procedure is identified as optional, and the performance of this procedure depends on the test specific data quality objectives, and end use of the data.

The test-specific precision may be determined by conducting paired-runs. Paired runs aid in identifying possible suspect data and provide backup in the event one train is invalidated. Performing paired runs depends on the test-specific data quality objectives.

The reaction of gaseous HCl with ammonia (NH₃) to form solid ammonium chloride (NH₄Cl) is well known. At stack temperatures common to the exits of baghouses and ESPs at mineral calcining facilities (that is, 250 to 450°F or 121 to 232°C), an equilibration between the gaseous HCl/NH₃, the condensed NH₄Cl(s), and the effluent particulate matter can exist. It is impossible to know the exact partition ratio between the gas and particulate phases of these compounds in the sampling system. Furthermore, it is very difficult to control the effects of these partitioning reactions within the various sampling system components.

Note 4-Use of this method is cautioned when trying to quantify HCl (g) in the presence of ammonium chloride and ammonia.