New approach to size monitoring

UK-based Whitehouse Scientific produces one of the world's largest selections of NIST traceable glass microspheres for measuring particle size. The polydisperse range claims to offer the most comprehensively analysed reference standards available, with seven grades covering sizes from 0.1 to 2000µm.

The monodisperse range comprises more than 50 ultra narrow size distribution glass microspheres, from 10µm to more than 1000µm. The Monospheres are available in sets of five single-dose dry packs, from 0.1 to 5g depending on size, and are said to have excellent long term stability. Each pack is supplied with a certificate of traceability.

The company also uses the NIST-traceable precision glass microspheres in a new approach to sieve calibration, which eliminates the need to send sieves away. Whitehouse's narrow size distribution standards are certified by highly accurate electroformed sieves and by microscopy. They are packaged in single shot bottles, sufficient to analyse more than 80% of the apertures in 200mm diameter sieves, from 20µm to more than 3.35mm.

The percentage of standard passing through the sieve is calculated and the mean aperture size determined from a calibration graph supplied with each standard. Calibration is fast, repeatable and independent of the method of sieve shaking.