Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D3175-20 – Standard Test Method Technical Guide
🔬 Scope and Key Terminology
ASTM D3175-20 is an empirical standard test method for determining the yield of gaseous products, exclusive of moisture vapor, in the analysis sample of coal and coke. The resulting volatile matter value is a critical parameter for coal classification by rank (ASTM D388) and for coke evaluation. The standard explicitly defines three key phenomena observed during the heating process to help operators identify potential interferences:
| 🔬 Phenomenon | 📐 Definition (D3175-20) | ⚡ Associated Material |
|---|---|---|
| Popping | Unseating of the crucible cover due to swelling of the test sample resulting in mechanical loss of the test material. | Strongly swelling coals |
| Sparking | The evolution of gaseous products at a rate sufficient to mechanically carry solid particles out of the crucible; particles escaping at higher temperatures become incandescent. | Non-swelling coals and cokes |
| Swelling | The change in volume which takes place when coal is heated under conditions allowing the softened coal to expand freely in a direction normal to the plane of heating. | Coal in general |
⚙️ Test Procedure and Controlled Conditions
Volatile matter is determined by establishing the mass loss resulting from heating a coal or coke under rigidly controlled conditions. The measured mass loss is corrected for the sample’s moisture content, as determined by Test Methods D3173/D3173M or D7582, to establish the volatile matter yield. To permit conformity with differences in sample behavior—such as swelling or caking—the standard provides two distinct procedures.
Tip: Because this test method is empirical (Section 1.2), strict adherence to the specified apparatus, heating rate, and final temperature is mandatory. Any deviation can significantly impact the reported volatile matter and compromise the comparability of results.
The standard relies on a robust framework of supporting ASTM practices and test methods to ensure accuracy and consistency across laboratories.
| ⚙️ Component / Role | 📏 Referenced Standard |
|---|---|
| Moisture Correction (Primary) | D3173 / D3173M |
| Moisture Correction (Alternative) | D7582 |
| Coal Sample Preparation | D2013 |
| Coke Sample Preparation | D346 |
| Terminology Base | D121 |
| Calculating to Different Bases | D3180 |
| Interlaboratory Precision Study | E691 |
📊 Interferences and Precision
The empirical nature of the volatile matter determination makes it critical to control all test parameters. The phenomena of popping and sparking represent significant interferences that can cause mechanical loss of the test material, invalidating the entire test result. The standard was approved by the U.S. Department of Defense and adheres to international standardization principles. Precision data for the method is determined in accordance with Practice E691.
Warning: Operators must remain vigilant for popping and sparking during the heating process. These events lead to mechanical loss of the test material and will invalidate the analytical result. Proper crucible configuration and following the two prescribed procedures for different sample behaviors are essential for safety and accuracy.
❓ Frequently Asked Questions
🔍 Why is the determination of volatile matter considered “empirical”?
The standard explicitly states in Section 1.2 that the test method for the determination of volatile matter is empirical. The results are entirely dependent on the specific heating rates, temperatures, crucible design, and procedural steps. Meaningful comparisons can only be made when the standard is followed rigidly.
💡 What is the purpose of correcting the mass loss for moisture?
The scope of the standard (Section 1.1) specifies the determination of “gaseous products, exclusive of moisture vapor.” The total mass loss measured includes evolved moisture. By subtracting the moisture value determined by D3173/D3173M or D7582, the operator isolates the yield of volatile hydrocarbons and other gases, which constitutes the reported volatile matter.
⚡ Which standards are cited for moisture determination in D3175-20?
The standard explicitly cites Test Methods D3173/D3173M (Moisture in the Analysis Sample of Coal and Coke) and D7582 (Proximate