ASTM D6735-01

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.

1.1 This method will measure the concentration of gaseous hydrochloric and hydrofluoric acids, and other gaseous chlorides and fluorides that pass through a particulate matter filter maintained at 177°C (350°F). This method is specific for sampling combustion effluent from mineral calcining industries and other stationary sources where the reactive/adsorptive nature of the particulate matter may affect measurements.

1.2 This method utilizes ion chromatography to quantify the aqueous samples, and thus measures only the C1^- and F ^- ions.

1.3 Based on a one-hour sampling run, the method will provide results of known accuracy and precision for chloride and fluoride in-stack concentrations of 0.5 ppm (v) dry or greater. Extending the run duration and sampling a greater volume of effluent will extend the range to lower concentrations.

1.4 This method includes optional post-test quality assurance procedures to assess the bias of the test results, and optional paired sample train runs to assess the precision of test results.