ASTM D4940-98(2003)

By-product abrasives manufactured from slags that are air cooled or quenched with pure water, normally contain low concentrations of ionic materials, as do mined mineral abrasives. However, slags quenched with seawater or other contaminated water, contain high amounts of ionic material as does seashore sand. This contamination of the abrasive can transfer to the steel surfaces being blasted, where it may accelerate corrosion. This test is useful in establishing the cleanliness of the abrasive at the jobsite.

This test method provides a value that indicates the concentration of total water soluble ions based on their electrolytic mobility. Thus, it provides an indication of ionic corrosion potential.

Note 1—A typical value of conductivity for a high level of contamination is 500 μmho/cm. A typical value for a low level of contamination is 50μ mho/cm.

1.1 This test method describes a procedure for rapid evaluation of abrasives for the presence of ionic contamination by determining the total concentration of water soluble ionic contaminants by means of a conductivity test.

1.2 This test method does not identify the ionic species present nor provide quantitative results on each species.

1.3 This test method is based on a volume comparison among abrasives of similar sizes. A volume comparison is more closely related to surface area of the abrasives than is a weight comparison.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.