Name the reporting quantity
ASTM D613 addresses diesel-fuel cetane number. ASTM D4737 addresses a calculated cetane index using a four-variable equation. A calculated index is an estimate based on other fuel properties; it is not the same result with a different label.
Derived cetane number is another term used in fuel testing. Do not combine “derived cetane number” and “calculated cetane index” into one ambiguous requirement. State the method number that defines the requested result.
Check the sample and application
Before choosing a method or material, establish the fuel composition and check the applicable scope, limitations and edition. Do not assume a calculation or calibration material is suitable for every diesel formulation. This article does not decide whether a particular sample meets a method’s scope.
Build the supply enquiry
Provide the reporting quantity, complete method designation, instrument model and intended use. Specify whether you need reference fuel, a check material or a replacement consumable, and include any existing catalogue number.
Method references in this article are not product-compatibility certificates. Confirm the proposed product’s identity, documentation and suitability before purchase or use.