Guideline VDI 2066 Part 1 specifies a manual gravimetric reference measurement method for the determination of the dust load (dust content) and the dust mass flow of a dust/gas mixture flowing through a defined cross-section (e.g. stacks, pipelines or ducts). Such measurement tasks mainly arise, if dust emissions have to be determined e.g. in case of a check of compliance with limit or guarantee values, calibration of automated dust emission measuring systems, performance measurements at dust precipitators, and during check or optimization of process parameters. This guideline can be applied at different dust contents according to the following application ranges, and in case of wet or water-vapour saturated flue gas as well as in case of over-saturated flue gas with water droplets. It is applicable in the following application ranges: Application Range A: cleaned-up gas with concentrations up to 50 mg/m3, Application Range B: cleaned-up gas with concentrations up to 150 mg/m3, Application Range C: intermediate gas with concentrations up to 2 g/m3, Application Range D: raw gas with concentrations e.g. up to 100 g/m3 The sampling time of a single measurement is usually 30 min. Guideline VDI 2066 Part 1 is applicable to measurements at stationary sources. For the Application Range A, the technical requirements of this guideline are identical to those of DIN EN 13284-1. In this case, they fulfil the normative requirements of DIN EN 13284-1. For plants covered by European Directives [G5; G6], the dust measurement according to DIN EN 13284-1 is strictly required. This applies to plants the erection and operation of which is regulated by the 13th or 17th Ordinance [G2; G3] on the implementation of the German Federal Immission Control Act [G1]. If the dust measurement is carried out for these plants in accordance with Application Range A of this guideline, the equivalence with DIN EN 13284-1 shall be indicated in the measurement report. This guideline also provides procedures for special operating conditions and interfering components in the flue gas.