Nalkree For the sampling of coal using mechanical sampling systems see D Practice for the Mechanical Sampling of Coal. Need more than one copy? Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Combining values from the two systems may result in non-conformance with the standard. When Is a Coal Sample a Sample? 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.

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A number in parentheses indicates the year of lastreapproval. The task ofobtaining a sample of reasonable weight to represent an entire lot presents a number of problems andemphasizes the necessity for using standard sampling procedures.

Coal is one of the most difficult of materials to sample, varying in composition from noncombus-tible particles to those which can be burned completely, with all gradations in between. The task isfurther complicated by the use of the analytical results, the sampling equipment available, the quantityto be represented by the sample, and the degree of precision required.

This practice gives the overall requirements for the collection of coal samples. The wide varietiesof coal-handling facilities preclude the publication of detailed procedures for every sampling situation. The proper collection of the sample involves an understanding and consideration of the physicalcharacter of the coal, the number and weight of increments, and the overall precision required.

The sample is tobe crushed and further prepared for analysis in accordance withPractice D However, the procedures for dividing largesamples before any crushing are given in this practice. For thesampling of coal using mechanical sampling systems seeD Practice for the Mechanical Sampling of Coal. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.

It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Referenced Documents2. Example:the observed and true sulfur content of a coal consignment. This measure is affected by chance errors as well as by bias. Current edition approved Jan.

Published February Originallyapproved in DOI: United States Givenadequate information about the sample results obtained usingprobability sampling, the probability distribution of samplingerrors can be estimated. Summary of Practice4. Significance and Use5. Because of the variability of coal and the wide variety ofsampling equipment, caution should be used in all stages ofsampling from system specifications and equipment procure-ment to equipment acceptance testing and actually taking thefinal sample.

Increment Collection Classification6. Thesedesignations are to be used for sampling specifications and fordescriptions of sampling programs and sampling equipment.

This includes thatin which the increment is collected in precise accord withpreviously assigned rules on timing or location that are free ofany bias. Type I selection increments generally yield moreaccurate results. Four conditions are recognized The distancebetween the parallel faces shall not be less than three times thenormal top size of the coal. Systematic 2. Random 1. Two spacingmethods are recognized: systematic and random.

Systematicspacing is usually preferable. Organization and Planning of Sampling Operations7. Parties claiming to use thispractice must adhere to the procedures as set out in thisstandard. If the sampling is not done in accordance with theprocedures set out in this practice then that sample may not besuitable for comparison with a sample collected by the proce-dures described in this practice.

Since it may be impracticableor impossible to take another sample of a given lot of coal it isessential that parties agree on sampling procedures prior toundertaking sampling. Proper sampling involves an under-standing and proper consideration of the minimum number andweight of increments, the size consist of the coal, the conditionof preparation of the coal, the variability of the constituentsought, and the degree of precision required.

This variabilityincreases with an increase in free impurity. A coal high ininherent impurity and with comparatively little free impuritymay exhibit much less variability than a coal with a lowinherent impurity and a relatively high proportion of freeimpurity. For most practical purposes, an increase in the ashcontent of a given coal usually indicates an increase invariability. It is imperative that not less than the minimumspecified number of increments of not less than the minimumspecified weight be collected from the lot.

For Condition D, theincrements shall be of equal weight. The best possible increment is a full cross-sectioncut removed from a stopped belt, Classification I-A-1 in Table1.

The best possible increment from a flowing stream of coal isone obtained by moving a cutter device entirely across thestream at a uniform speed, the same for each increment, intoone side of the stream and out of the other, without allowingthe receptacle to overflow Classification I-B-1 in Table 1. Classificationmethods given in Table 1 are listed in order of decreasingreliability.

The highest possible classification method, wher-ever feasible, should be used. Details of sampling proceduresshould be agreed upon in advance by all parties concerned. Thisdistribution is related to the entire volume of the lot, not merelyits surface or any linear direction through it or over it. Ifcircumstances prevent the sampler from applying thisprinciple, the lot is sampled only in part, and the gross sampleis representative only of this part. Thesampling device shall be of sufficient capacity to completelyretain or entirely pass the increment without spillage at themaximum rate of coal flow.

If there is a lapse in time between these two events, consider-ation should be given by both the purchaser and the seller tochanges in moisture during this interval and the consequentshift in relationship of moisture to the true quality of the coalat the instant when ownership of the coal transfers from one tothe other.

The circulation of air through equipment must be reduced to aminimum to prevent both loss of fines and moisture.


ASTM D2234: Standard Practice for Collection of a Gross Sample of Coal



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ASTM D2234





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