MANUAL Published: 17 December 2018

Chapter 13 | Methods for Assessing Stability and Cleanliness of Liquid Fuels


Stability generally refers to the resistance of a fuel to changes in its chemical quality, while cleanliness is a parameter relating to the physical presence of contaminants: most notably water and sediment, but also degradation products such as gums, asphaltenes, or polymerized products that can form following production of a fuel. There are significant differences in cleanliness and stability between light fuels (distillates) and residual fuels, and very different test methods are required, especially for predicting extended storage. Also, while these would appear to be unrelated properties, the presence of contaminants can exacerbate reactions resulting in a loss of storage stability. Fuel contaminants include materials such as water and rust or other particulate matter introduced subsequent to fuel manufacture, and fuel degradation products formed in fuel during extended storage as a manifestation of fuel instability. The increasing diversity of products in today's market, ranging from highly refined gasoline, through aviation turbine fuel and ultra-low sulfur diesel fuel, to residual fuel oil as well as newer biofuels, such as ethanol and alkyl ester biodiesel (fatty acid methyl esters), demands an equally diverse array of test methods. Consequently, many test methods have been developed over the years, with quite a few new methods having been introduced within the past decade for assessing the stability of petroleum products, biofuels, and blends of the two and determining their cleanliness. Many accelerated stability methods are available for assessing the storage potential of conventional fuels, biofuels, and blends of the two. This chapter is intended to provide an overview of the test methods available for assessing stability and cleanliness of liquid fuels.

Author Information

Forester, David
Fuel Quality Services Inc., Flowery Branch, GA, US
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Pages: 211–224
DOI: 10.1520/MNL120170026
ISBN-EB: 978-0-8031-7109-1
ISBN-13: 978-0-8031-7108-4