The Falling Sand Abrasion Tester - Model 820 is a popular apparatus used to measure the resistance to abrasion of paint, lacquers and other organic coatings.  Abrasion results from abrasive particles falling through a guide tube and impinging the test specimen, until the substrate becomes visible.
 
Based on a design described in ASTM D 968 and other internationally recognized test standards, the Falling Sand Abrasion Tester consists of an 8" diameter sand reservoir which includes a 60° taper funnel.  Standardized abrasive particles placed in the reservoir are released to a guide tube by an abrasive flow gate key.  The guide is a 36" straight, smooth-bore tube which contains the abrasive particles as they fall.  Specimens are fixed under the guide tube at a 45° angle in a receptacle that includes an opening at the bottom allowing the abrasive particles to be collected in a container.  A sturdy base and support system hold the apparatus in a vertical position.