It is intended that this practice be used to provide a sample representative of the coal from which it is collected. Because of the variability of coal and the wide variety of mechanical sampling equipment available, caution should be used in all stages of the sample collection process, the design of sampling system specifications, the equipment procurement and the acceptance testing of installed equipment.

After removal from the sampling system and further preparation (Practice D 2013), the sample may be analyzed for a number of different parameters. These parameters may define the lot's value, its ability to meet specifications, its environmental impact, as well as other properties.

1.1 This practice is divided into 4 parts. These 4 parts represent the previous standards D 7256/D 7256M, D 4916, D 4702, and D 6518. These 4 standards are the 4 that govern the mechanical sampling of coal and have been combined into one document for the ease of reference of the users of these standards.

1.2 Part A—Mechanical Collection and Within-System Preparation of a Gross Sample of Coal from Moving Streams—Covers procedures for the mechanical collection of a sample under Classification I-B-1 and I-B-2 (Practice D 2234/D 2234M) and the within-system preparation (reduction and division) of gross samples utilizing various components of the mechanical sampling system.

1.2.1 Part A describes mechanical sampling procedures for coals (1) by size and condition of preparation (for example, mechanically cleaned coal or raw coal), and (2) by sampling characteristics.

1.3 Part B—Mechanical Auger Sampling——Describes procedures for the collection of an increment, partial sample, or gross sample of material using mechanical augers. Reduction and division of the material by mechanical equipment at the auger is also covered. Further manual or mechanical reduction or division of the material elsewhere shall be performed in accordance with Practice D 2013.

1.4 Part C—Quality Management of Mechanical Coal Sampling Systems—Is applicable to the quality management of cross-belt, falling stream, and auger sampling systems.

1.4.1 Spacing of increments pertains to the kind of interval between increments. Intervals can be defined in quantitative terms, such as units of time or mass, or in terms of position over the lot.

1.4.2 Spacing of Increments for Cross-Belt and Falling Stream Samplers—Cross-belt and falling stream type mechanical sampling systems take increments based on time, either at fixed time intervals or at random times during a fixed time strata. Some falling stream samplers can take increments based on equal mass of coal sampled as determined by scales. The sections of this practice that pertain to cross-belt and falling stream samplers describe procedures for only time-based sampling systems. This time-based inspection guideline will satisfy most criteria for mass-based or combination mass-based and time-based sampling systems. If there are items that are not covered, the inspector should refer to the manufacturer's literature.

1.4.3 Spacing of Increments for Auger Sampling—The spacing of increments collected by auger sampling systems is defined in terms of position over the lot.

1.4.4 It is essential that the inspector have the documentation listed in Section 2 of this practice when conducting an inspection.

1.5 Part D—Bias Testing of a Mechanical Coal Sampling System—Presents sample collection and statistical evaluation procedures for testing mechanical sampling systems, subsystems, and individual system components for bias. It is the responsibility of the user of this practice to select the appropriate procedure for a specific sampling situation.

1.5.1 Part D does not purport to define an absolute bias. Bias defined by this practice is the difference between the population mean of the mechanical sampler test results and the accepted reference value.

1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text the inch-pound units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, use each system independently of the other. Combining values from the two systems may result in nonconformance with the standard.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see section 16.1.