Abstract
Standard Reference Material (SRM) 2806: Medium Test Dust in Hydraulic Fluid represents a series of reference materials certified by the National Institute of Standards and Technology (NIST) used to calibrate liquid-borne optical (or automatic) particle counters applied in a wide range of industrial, aerospace, and military applications. The series, including SRM 2806b, and SRM 2806d, was manufactured for NIST by IFTS, Institut de la Filtration et des Techniques Séparatives International Filter Testing Services, in France. An important factor for the acceptance of the material for certification was the degree of bottle-to-bottle homogeneity, which was evaluated by both IFTS and NIST. A statistical graphics methodology was developed that provided immediate visual as well as quantitative statistical metrics with which to characterize the SRM. This NIST-developed approach was used in four studies to assess the homogeneity of the material during both its production stage and its finished bottled-product stage. IFTS performed measurements using an optical particle counter for on-line quality assurance and sampled 40 bottles of the finished 400 bottle series to determine homogeneity from the particle size distribution. NIST also determined the particle size distribution of the finished material and performed microscopy to look for possible contaminant material in the suspension. An accelerated aging experiment was conducted on both materials (2806b and 2806d) to verify their stability.