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D197-19 – Standard Test Method Technical Guide
ASTM D197-19 provides a standardized test method for determining the fineness of pulverized coal through sieve analysis. This method is specifically designed for samples taken from dry pulverizing operations and is critical for evaluating pulverizer performance, optimizing combustion efficiency, and assessing carbon loss.
📐 Scope and Applicability
This test method covers the determination of fineness by sieve analysis of coal sampled from a dry pulverizing operation. It is explicitly not applicable to products of wet milling or to fines that have clustered into an agglomerated mass. The standard serves as a primary tool for evaluating pulverizers and pulverizer systems against fineness specifications. The values stated in SI units are regarded as the standard.
⚙️ Apparatus and Test Setup
The standard mandates specific equipment to ensure reliable and repeatable fineness analysis results.
- Sample Containers: Heavy vapor-impervious bags or noncorroding cans with airtight, friction-top or screw-top seals and rubber gaskets.
- Drying Oven: Capable of circulating air at 10 °C to 15 °C (18 °F to 27 °F) above room temperature, with a strict maximum of 40 °C (104 °F). Air exchange rate must be controlled to 1 L/min to 4 L/min.
- Mechanical Sieving Machine: Must provide a combination of circular motion and tapping action. The action must allow for complete sieving within the designated time frame without generating new fines through particle degradation.
⚠️ Critical Sieve Care: The finer mesh sieves (e.g., 75 µm and 45 µm) are susceptible to damage from pressure or scraping. Each sieve must be closely inspected before use and discarded immediately if damage is evident.
📊 Sieve Specifications and Fineness Measurement
The test relies on a specific stack of sieves conforming to ASTM E11. Frames are 203 mm (8 in.) in diameter with a height of 50.8 mm (2 in.) or 25.4 mm (1 in.). The selection of specific sieve sizes for a test is optional depending on the objective.
| 🟦 Sieve Designation | 📏 Nominal Aperture | 🎯 USA Standard No. |
|---|---|---|
| 2.36 mm | 2.36 mm | No. 8 |
| 1.18 mm | 1.18 mm | No. 16 |
| 600 µm | 600 µm | No. 30 |
| 300 µm | 300 µm | No. 50 |
| 150 µm | 150 µm | No. 100 |
| 75 µm | 75 µm | No. 200 |
| 45 µm | 45 µm | No. 325 |
💡 Drying Oven Tip: To prevent alteration of the coal sample, the oven temperature must strictly not exceed 40 °C (104 °F). Air changes should be