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D5115-90 – Standard Test Method Technical Guide
ASTM D5115-90 (Reapproved 2004) provides a standardized framework for the empirical determination of Refuse-Derived Fuel (RDF) quality. Recognizing the inherent difficulty in obtaining a perfectly representative single sample from a heterogeneous, multi-ton lot of RDF, this method relies on a robust statistical approach involving multiple samples collected over a designated production period to provide a reliable estimate for contractual and operational purposes.
🔄 Sampling Methodology and Protocol
The core protocol of D5115 mandates the strategic collection of twenty (20) gross samples of RDF at intervals over a one-month production period. The laboratory analysis results from this complete set of samples are mathematically averaged to establish the representative fuel quality for that month. For the physical collection, the standard specifies the use of a Conveyor Belt Sample Divider, which must consist of two vertical wall members matching the belt profile, with a clear space between them of not less than three times the maximum particle size of the RDF stream to ensure an adequate cross-section is captured.
⚖️ Statistical Nature of Results: The standard’s introduction clearly notes that it provides an “empirical estimate that is adequate.” It explicitly states it is “not possible to gather a sample…with assurance that the sample is representative.” Therefore, the averaged result is an estimate designed for contractual reliability, not a definitive point measurement of a specific sub-lot.
| 📏 Sampling Parameter | 🔢 Specification |
|---|---|
| Number of Gross Samples Required | 20 |
| Standard Collection Period | One Calendar Month |
| Minimum Sample Divider Gap | 3x Maximum Particle Dimension |
| Standard Unit System for Values | Inch-Pound Units |
📊 Key Analytical Determinations
Once the twenty gross samples are collected and prepared according to ASTM E829, they undergo a defined suite of standard analyses to characterize fuel quality. The specific test methods referenced within D5115 provide critical procedures for determining the properties that define the RDF’s thermal and physical characteristics for contractual use.
| 📐 Property Measured | 🔬 Reference ASTM Method |
|---|---|
| Gross Calorific Value (Heat Content) | E 711 |
| Residual Moisture Content | E 790 |
| Ash Content (Analysis Sample) | E 830 |
| (Macro) Thermal Characteristics | E 955 |
| Data Calculation & Base Conversion | E 791 |
| Laboratory Sample Packaging/Shipping | E 954 |
The average of the results from the twenty samples for each parameter forms the definitive fuel quality profile for the month. Calculations must strictly follow the protocols in E 791 to express results on the correct basis (as-determined, dry, etc.). This ensures consistency for contractual agreements between producer and user.
💡 Integrated Method System: D5115 functions as the top-tier protocol in a system of methods. The sampling strategy (D5115) directly feeds sample preparation (E829), which provides material for chemical/physical tests (E711, E790, E830, E955), followed by standardized data conversion (E791). Users must have access to all referenced documents for full compliance.
📈 Contractual Significance and Data Interpretation
The primary use case articulated in the standard is to facilitate objective contractual adjustments between RDF producers and users regarding fuel quality over a production cycle. The use of twenty samples minimizes the impact of short-term variability in the RDF stream. It is crucial to note that the final reported values represent an average for the month, not the quality of any single shipment, production hour, or specific point in the process. This provides a stable and auditable metric for financial settlement.
❓ Frequently Asked Questions
🔍 What is the minimum number of samples required to constitute a valid monthly estimate?
A full set of exactly twenty (20) gross samples must be collected, analyzed, and averaged to constitute a valid monthly fuel quality determination under the protocol of D5115. Anything less does not fulfill the standard’s requirements for statistical validity.
💡 Can this standard be applied to production periods other than one month?
Yes. Section 1.2 of the standard expressly permits this. If twenty (20) gross samples are gathered, analyzed, and averaged over any specific designated period, the method can be applied to define the fuel quality for that specific timeframe.
⚡ Which unit system is considered the standard for reporting results under this method?
Section 1.3 of the standard clearly states that inch-pound units are to be regarded as the standard. Values provided in parentheses (SI units) are for informational purposes only and do not carry the same weight for formal compliance.
📌 What is the specific dimensional requirement for the conveyor belt sample divider?
Per Section 6.1, the apparatus requires a sample divider with vertical walls matching the belt profile. The critical requirement is a minimum gap between the two walls of not less than three (3) times the maximum particle dimension present in the RDF stream.