ASTM D4621 Standard Guide for Quality Management in an Organization That Samples or Tests Coal and Coke
12. Collection, Intake, and Management of Test Samples
12.1 If the laboratory collects gross samples, it can demonstrate that personnel engaged in sample collection are adequately trained and able to accomplish the tasks in accordance with ASTM prescribed methods (for example, procedures in Practice D2234/D2234M).
12.2 There is a procedure to ensure that the laboratory and customer agree on the method of sampling for a particular job, and that a description of or reference to the test method used becomes a part of the sample log and final report.
12.3 Any mechanical sampling system for which the laboratory has responsibility is:
12.3.1 Tested for bias when it is put into service or when substantial modifications have been made;
12.3.2 Tested for bias on a relatively short-term, routine schedule, generally employing a simplified procedure;
12.3.3 Maintained in accordance with written procedures on a specified, routine basis;
12.3.4 Checked before and during the collection of the gross sample, including determination that sample mass is consistent with product throughput.
12.3.5 The laboratory maintains records of the condition of, maintenance and modifications performed on, and bias test results from mechanical sampling systems for which it has responsibility.
12.4 The laboratory has documented procedures for the receipt, retention, and safe disposal of test samples.
12.5 To ensure that there can be no confusion regarding the identity of samples at any time, the laboratory has a documented system for uniquely identifying samples to be tested. The laboratory assigns to each sample a unique laboratory identifier (ID), for instance, a unique number of letter/number combination. Each sample or subsample is labeled with its ID in a way that it will not be separated from the sample or rendered unreadable during its residence in the laboratory. All laboratory work records, intermediate sample containers, data sheets, and reports clearly show the laboratory ID. The ID number is included on any invoice for work on the sample.
12.6 For each sample, a sample log is maintained that contains information required for historical reference, such as account or job number, mass or volume of sample, condition of sample, type of sample, top size of sample, person or organization submitting sample, location from which the sample was collected (if known), date and time of collection (if known), date and time samples were received in the laboratory, and type of container. The sample log is also used to maintain a record of chain-of-custody of a sample.
12.7 Instructions provided by the customer about the sample are communicated to appropriate personnel and are followed by them.
12.8 Where there is any doubt as to the sample's suitability for testing, where the sample does not conform to the description provided, or where the test required is not fully specified, a specified, responsible individual consults the client for further instruction before proceeding. Laboratory personnel have specific responsibilities to establish whether the sample has been adequately prepared, or whether the client requires preparation to be undertaken in or arranged by the laboratory.
12.9 Because oxidation and moisture changes occur readily to many coal samples, documented practices are designed to minimize deterioration or damage to the test sample during storage, handling, preparation, and testing (Note 6). Where a test sample or portion of a sample is to be held after testing (for example, for reasons of record or to enable check tests to be performed later), the laboratory has storage and security arrangements that protect sample condition and integrity.
NOTE 6 - Well-sealed solid containers, Mylart or foil-lined bags preserve sample condition best. However, the condition of even a well-stored sample of coal (especially low-rank coal) almost always changes with time. Therefore, the laboratory should normally test samples within a few days of receipt. Data from analyses of samples that have been stored for more than a few days should be used cautiously.
13. Sample Preparation
13.1 Appropriate personnel can demonstrate capability to prepare samples in accordance with Practice D2013 (for coal) or Practice D346 (for coke), or both.
13.2 Equipment for size reduction and sample division is appropriate for the task and is used appropriately.
13.2.1 Riffles or other dividers are tightly enclosed to prevent dust loss, have correct opening or chute sizes, and are used in an appropriate manner (Practice D2013).
13.2.2 Essentially all sample material is recovered from preparation equipment such as riffles, crushers, and pulverizers to prevent creation of a biased sample.
13.2.3 To prevent sample contamination, size-reduction and sample division equipment are thoroughly cleaned after each use.
NOTE 7 - Vacuuming is preferred for cleaning. The use of an air blast to clean equipment is not advisable if it disperses dust into the atmosphere. Although thorough cleaning is always appropriate, it is especially important before small quantities of sample are to be processed.
13.3 Sample integrity is preserved while samples are being processed or while they are awaiting processing. In particular, samples are protected from temperature extremes and are kept in sealed containers to minimize moisture changes, oxidation, and contamination.
NOTE 8 - Although not mandatory, it is desirable to conduct some tests to assess the magnitude of any incidental moisture changes that might occur during routine storage, reduction, and division of gross samples. The protocol for such tests is left to the individual laboratory. If tests are conducted, results should be documented and made accessible to customers or clients upon request. If significant changes are detected, the procedure should be modified to further minimize such inadvertent changes.
13.4 Air-drying is carried out according to procedures specified in Practice D2013 or Test Method D3302.
13.5 The magnitude of the variance attributable to routine sample preparation procedures has been measured and documented (see Annexes in Practice D2013), and is made available to customers or clients when requested. This may not be practical where customers provide only small quantities of sample. However, where coal from a single source or a limited number of sources is tested, the assessment of variance is recommended.
13.6 Sample mass at each stage of division conforms to Practice D2013.
13.7 Particle sizes of crushed or pulverized samples are checked routinely to ensure that samples meet the appropriate size criteria. Screens in size reduction equipment are frequently examined visually, preferably before each use.
13.8 Pulverized samples are mixed on a mixing wheel (a child's toy jack or "jack rock" may be placed in the container to improve mixing). To minimize size segregation (commonly sifting of finest particles to the bottom of a container), samples are not unduly shaken or tapped after mixing, and the aliquot used in a test is recovered from the container in a manner that minimizes selecting a biased size fraction. Samples removed from storage or that have been standing for extended periods are remixed before testing.
13.8.1 Test samples are maintained in well-sealed bottles or other containers until analyzed or tested and are exposed for as short a period as possible to the atmosphere.
NOTE 9 - It is desirable to perform some tests to demonstrate that the container lids do seal well, thereby preventing moisture changes and oxidation. A convenient test is to determine, by weighing, if water evaporates when sealed in typical containers.
14. Calibration of Equipment
14.1 A program of calibration, verification, or validation of equipment is carried out when equipment is first placed in service or when it has been placed in service after repair or modification.
14.2 Wherever possible, calibration is performed using certified reference materials (CRMs) or certified measuring devices (for example, temperature-measuring devices).
NOTE 10 - It is good practice to verify that the certified value for a reference material is reliable, for example, by comparing results from different batches of the reference material, that is, "old" bottle versus "new" bottle.
14.3 There is a documented program for frequently verifying the calibration status of test equipment between routine, scheduled recalibrations.
NOTE 11 - For most test methods, it is appropriate to verify calibration with a device, reference material, or control material daily or at the beginning of each shift. For some tests, more frequent verification is required; for some, less frequent verification is appropriate. The quality manager uses his/her best judgment to define the frequency required for each test.
14.4 Calibrations and calibration verifications are conducted at different times of day, on different days of the week, and by different personnel (preferably those who test or analyze samples).
14.5 An appropriate number of determinations are used to establish or verify calibrations.
14.6 Data from calibrations and calibration verifications are maintained in statistical or control chart format (Appendix X3), and are kept within reasonable proximity to the equipment to which they apply.
14.7 Written policies define the level of nonconformance by calibration verification where action needs to be taken to correct nonconforming equipment or procedures (see "control limits" in Appendix X3). Upon detection of nonconformance, the piece of equipment is immediately removed from service and is recalibrated or repaired prior to further use for measuring or testing. Permanent records are maintained of actions taken when nonconforming incidents are detected and remedied. Following repairs or modifications, the equipment is always calibrated.
14.8 Certified reference materials are used for calibration only and for no other purpose, unless the laboratory can demonstrate that their performance as reference materials is not compromised by such other use. If CRMs are unavailable or their expense is not warranted, then other appropriate reference materials are used. The values of the other reference materials are verified and validated in some appropriate fashion, for example, by comparison with CRMs or by having them tested by another competent laboratory or by another standardized procedure.
14.8.1 Special care is taken to minimize oxidation and changes in moisture content of any coal samples used as reference materials.
NOTE 12 - When certified values of coal-based reference materials are reported on a dry basis, it is generally necessary to determine residual moisture values and make appropriate calculations to adjust the certified values from the dry to the as-determined basis. It is poor practice to use dried coal samples for calibration, as they may oxidize while drying and absorb moisture from the atmosphere after being dried. Ifa dried reference material is used, it is good practice to dry and weigh it in the crucible or boat to be used in the test, and to then keep them in a desiccator.
14.8.2 Reference materials are discarded when less than 5 % of the original mass remains in the container because this fraction is often size-biased.
14.9 Where traceability of test results to certified reference materials is not possible, the laboratory provides satisfactory evidence of accuracy of test results by participating in a suitable program of interlaboratory comparisons or proficiency testing (16.3).
15. Conducting Procedures and Tests
15.1 The laboratory uses appropriate, documented standard test methods and procedures for all tests and related activities, such as, sample collection, preparation, handling, transport, and storage.
15.2 All instructions, SOPs, manuals, and reference data relevant to the technical work of the laboratory are up to date and are readily available to the staff.
15.3 If the client does not specify test methods, the laboratory uses test methods, wherever possible, that national or international bodies (for example; ASTM, ISO) have standardized. The laboratory has in place a policy for advising a client when the test method requested is considered inappropriate or out of date.
15.4 Where it is necessary to use test methods that have not been established as standard, the laboratory attempts to use test methods that have been published by reputable technical organizations or that have been published in reputable scientific texts or journals. Their use is subject to agreement with the client. The test methods are fully documented and validated, and the documentation is available to the client and other recipients of the relevant reports.
15.5 Procedures are in place to ensure that only personnel who are fully trained and capable of performing a procedure or test actually perform that procedure or test.
15.6 Personnel who are responsible for performing a procedure or test method are also responsible for verifying calibration, for using control samples, and for interpreting and applying the results from control samples.
15.7 A specific form is used to record intermediate and final data for each test method (unless data are entered directly into or are captured by computer). A documented procedure is used to ensure accurate data input to the worksheet or computer.
15.8 Individuals not responsible for their initial execution, check hand calculations and data transfers.
15.8.1 For ease of reference and to facilitate auditing, a single document that shows all calculation procedures employed for all test methods is included in or referenced by the quality manual.
15.9 Where computers or automated equipment are used to capture, process, manipulate, store, retrieve, or report test data, the laboratory ensures that:
15.9.1 All appropriate requirements of this guide are complied with;
15.9.2 Computer software is documented and adequate for use, and has been verified to provide correctly calculated results and to apply them to the correct sample;
15.9.3 Procedures are followed to maintain the integrity of data entry or capture, storage (including appropriate backup), processing and transmission; and
15.9.4 Computers and automated equipment are maintained to ensure proper functioning and are provided with the environmental conditions and operating procedures necessary to ensure the integrity and validity of test data.
15.10 For additional information on maintaining integrity in the highly computerized laboratory, see Guide E 1579.
15.11 Appropriate procedures ensure the security of data including the prevention of unauthorized access to, and the unauthorized amendment of written and computer records.