ASTM D7821-12

1.1 This test method covers a technique for field testing the concentration of aqueous urea-based diesel exhaust fluid (DEF) prescribed for use in diesel engines equipped with selective catalytic reduction technology and is not intended to circumvent or replace the more accurate determination of urea content by refractive index laboratory method, described in ISO 22241-2, Annex C.

1.2 This test method is designed solely as a quantitative test to determine the concentration of urea in DEF and does not purport to determine the quality of DEF nor to detect trace or other contaminants therein. Biuret content of DEF creates a known bias in this test method. See section 1.3 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.

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.