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D4702-07 – Standard Test Method Technical Guide
📐 Scope and Applicable Systems
This standard practice, designated D 4702 – 07, establishes quality assurance criteria for the operation of mechanical coal sampling systems. It is applicable to cross-belt, falling-stream, and auger sampling systems. The standard provides recommendations for performance monitoring, inspection, and maintenance necessary to maintain a sampling system’s capability to consistently obtain a representative sample. Values stated in SI units are to be regarded as the standard.
✅ Documentation Requirement: The inspector must have the documentation listed in Section 2, including Terminology D 121, Practices D 2013, D 7256/D 7256M, and D 4916, when conducting an inspection.
⚙️ Increment Spacing and Sampling Variants
The standard defines spacing of increments in quantitative terms such as units of time or mass, or in terms of position over the lot. Increment spacing is a critical parameter for ensuring sample representativeness.
Cross-Belt and Falling-Stream Samplers: These systems typically take increments based on time at fixed intervals or random times. The time-based inspection guideline will satisfy most criteria for mass-based or combination systems.
Auger Samplers: For auger sampling systems, the spacing of increments is defined strictly in terms of position over the lot.
| 🟦 Sampler Type | 📏 Increment Basis | 🎯 Primary Standard Reference |
|---|---|---|
| Cross-Belt | Time (Fixed or Random) | D 7256/D 7256M |
| Falling-Stream | Time or Equal Mass | D 7256/D 7256M |
| Auger | Position over the Lot | D 4916 |
🛡️ Safety Practices and Referenced Standards
This practice addresses quality assurance criteria for operation in accordance with Practices D 7256/D 7256M, D 2013, and D 4916. It provides recommendations for performance monitoring, inspection, and maintenance.
Safety Precautions: Personnel visiting facilities for observation of mechanical sampling system performance should immediately upon arrival report to the facility management. The inspector should ask for specific hazard information. This standard does not purport to address all safety concerns; the user must establish appropriate practices.
⚠️ User Responsibility: The standard does not purport to address all safety concerns. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
| 📐 Designation | 📌 Title |
|---|---|
| D 121 | Terminology of Coal and Coke |
| D 2013 | Practice for Preparing Coal Samples for Analysis |
| D 4749 | Test Method for Performing the Sieve Analysis of Coal |
| D 4916 | Practice for Mechanical Auger Sampling |
| D 7256/D 7256M | Practice for Mechanical Collection of a Gross Sample |
❓ Frequently Asked Questions
🔍 What specific mechanical coal sampling systems are covered under ASTM D4702-07?
This standard practice is specifically applicable to cross-belt, falling-stream, and auger mechanical sampling systems for coal.
💡 How are increment intervals defined for auger samplers under this practice?
For auger sampling systems, the spacing