ISO 9931:1991 PDF

Overview - ISO 9931:1991 (Coal pulverized-coal sampling)

ISO 9931:1991 specifies a standardized multipoint sampling method for pulverized coal conveyed by air or other gases in circular pipes of direct-fired coal systems. It defines the mechanical sampler, auxiliary equipment (dustless connection, cyclone, Venturi or ejector), sampling positions and procedures used to derive both the mass distribution of coal to burners and the particle-size distribution for pulverizer performance evaluation. Annexes A–C are informative.

Key topics and technical requirements

• Multipoint sampler design: a four-tip rotating sampler that samples 64 equally sized areas of a pipe cross-section (16 angular positions × 4 tips). The sampler head is aligned with the pipe axis and uses exchangeable tips.
• Pipe geometry limits: intended for circular pipes with internal diameters typically between 250 mm and 700 mm; sampling is subject to geometric constraints of the pipe and socket.
• Particle-size restriction: maximum particle size should be less than one‑third of the sampler tip aperture (document example: