Abstract
A new material has been certified to become Standard Reference Material (SRM) 2806b - Medium Test Dust in Hydraulic Fluid. SRM 2806b consists of trace polydisperse, irregularly shaped mineral dust particles suspended in hydraulic fluid. The certified values of SRM 2806b are the projected area circular-equivalent diameters of the collected dust particles from the hydraulic fluid. The dimensional measurements were determined from the area of the collected dust particles using images obtained from automated scanning electron microscopy (SEM) followed by image analysis. An automated SEM and an automated image analysis software allowed the processing of over 29 million particles. The dimensional calibration of the SEM images (actual length per pixel and thus the actual projected diameters) are traceable to the NIST Line Scale Interferometer (LSI) through a NIST calibrated Geller MRS-4XY pitch standard. The certified diameters are correlated with the numeric concentration of particles greater than each diameter, referred to as the cumulative number size distribution. SRM 2806b is intended to be used to calibrate liquid-borne optical particle counters in conjunction with the reference method ISO 11171:2010.