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D5142-09 – Standard Test Method Technical Guide
🏛️ Scope and Referenced Standards
ASTM D5142-09 specifies instrumental test methods for conducting the proximate analysis of the analysis sample of coal and coke. This standard covers the determination of moisture, volatile matter, and ash, along with the calculation of fixed carbon. Samples must be prepared in accordance with Method D2013 (Practice for Preparing Coal Samples for Analysis) and Practice D346 (Collection and Preparation of Coke Samples for Laboratory Analysis). The values stated in SI units are regarded as the standard.
The test methods described are explicitly not applicable to thermogravimetric analyzers using microgram size samples. The standard also references Terminology D121 for definitions of terms used throughout the methods.
⚠️ Referee Methods and Bias Correction: Results from these instrumental procedures have been shown to differ from those obtained using Test Methods D3173 (Moisture), D3174 (Ash), and D3175 (Volatile Matter) on some coals and cokes. Therefore, D3173, D3174, and D3175 are considered the referee test methods. If a relative bias is demonstrated, the instrumental results must be corrected or the instrument calibrated using samples of known proximate analysis.
⚙️ Test Procedure and Method Summary
Section 4 of D5142-09 outlines the scientific principles behind each determination. Each test is conducted under rigidly controlled conditions regarding temperature, time, atmosphere, specimen mass, and equipment specifications.
| 🟦 Parameter | 📏 Measurement Principle | 🎯 Key Controlled Variables | ⚡ Correction Factors |
|---|---|---|---|
| Moisture | Loss in mass of the analysis specimen upon heating | Temperature, Time, Atmosphere, Specimen Mass | None |
| Volatile Matter | Loss in mass of the moist or dried specimen upon heating | Temperature, Time, Atmosphere, Specimen Mass | Corrected for moisture content |
| Ash | Mass of the residue remaining after burning the specimen | Specimen Mass, Temperature, Time, Atmosphere | None |
| Fixed Carbon | Calculated by difference (100 – %Moisture – %Ash – %Volatile Matter) | N/A (Calculated) | N/A |
The analytical process can vary by instrument configuration. According to Section 4.4, some microprocessors allow for a fully automatic process where a specimen is placed in the instrument and moisture, volatile matter, and ash are determined sequentially in a single procedure. In other systems described in Section 4.5, the process is manually controlled, although the instrument may use a microprocessor to assist in controlling conditions and performing calculations.
📊 Key Measured Properties and Terminology
Understanding the exact nature of the sample is critical for proximate analysis. The as-determined results from D5142 often need to be converted to different bases (such as dry or dry ash-free) using Practice D3180. The standard relies on Terminology D121 for all relevant definitions.
💡 Practical Tip: While instrumental methods offer significant speed and automation, the standard mandates strict adherence to rigidly controlled test conditions. If your laboratory finds a consistent bias between the instrumental results and the referee methods (D3173, D3174, D3175), the equipment must be recalibrated or a correction factor must be derived and applied to the instrumental results to ensure compliance with the standard.
❓ Frequently Asked Questions
🔍 What materials are covered under D5142-09?
This standard specifically covers the determination of moisture, volatile matter, and ash, and the calculation of fixed carbon in the analysis sample of coal and coke. The samples must be prepared according to Practices D2013 and D346.
💡 When must instrumental results be corrected?
Instrumental results must be corrected if a relative bias is shown to exist when compared against the referee test methods (D3173, D3174, D3175). In such cases, the instrument must be calibrated using samples of known proximate analysis, or the results must be mathematically corrected.
⚡ Does this standard apply to all thermogravimetric analyzers?
No. The standard explicitly states in Section 1.1 that these instrumental test methods are not applicable to thermogravimetric analyzers using microgram size samples.
📌 How are the tests commonly conducted according to this standard?
Tests can be conducted using a fully automated microprocessor-controlled instrument or via a manually controlled analytical process. In a fully automated sequence, moisture, volatile matter, and ash may be determined sequentially from a single specimen in a single procedure (Section 4.4).