Standard Reference Samples (HGI-SRS)
Hardgrove Grindability Index (HGI)

The Hardgrove Grindability Index Standard Reference Sample (HGI-SRS) is a sample of coal used to calibrate instruments that are designed to determine the ease with which coal can be pulverized. The HGI value provides information for determining grinding power consumption and pulverizer capacities.

The HGI-SRS is prepared in a series of steps over several days. All procedures conform to American Society for Testing and Materials (ASTM) standard methods (Appendix A). Coal is purchased according to specifications. The Hardgrove Grindability Index is calculated on four splits (or portions), two each taken from the two reserved cans. The results are averaged to give the index for the entire lot. Cans of standard reference sample are shipped to customers upon request, along with a questionnaire designed by ASTM to obtain data on the quality of the sample. The data obtained on the questionnaire is used by ASTM to perform detailed statistical analysis of HGI-SRS production.

The National Energy Technology Laboratory has a Contributing Funds Agreement with ASTM to produce HGI-SRS, which are the Primary Standards for the D409 Analysis.

The HGI-SRS come in sets of four, containing 4 standards of approximate HGI values 40, 60, 80, and 110. Each set costs $800 for domestic orders and $870 for foreign orders to help cover the manufacturing and shipping costs.

For more information and to place an order, please see each of the following links:

HGI-SRS Order Form and Data Sheet [PDF-40 KB]