• Method adopted/last revised: 2008
• Method reapproved: None
• REF/ISBN: IP550-2936450
• Status: Current
• First printed in STM books: January 2008

Scope

This Standard describes a procedure for the determination of the mass percentage of sulfated ash from burner fuels derived from waste mineral oils.

NOTE 1 - For the purposes of this Standard, the terms '%(m/m) and %(V/V)' are used to represent the mass and volume fractions of a material respectively.

NOTE 2 - Waste mineral oils, comprising mainly of used lubricating oils, usually contain one or more of the following metals: barium, calcium, magnesium, zinc, potassium, sodium and molybdenum. The elements sulfur, phosphorus and chlorine can also be present in combined form. There is evidence that magnesium does not react in the same manner as alkali metals in this procedure. If magnesium is present, the data should be interpreted with caution.

NOTE 3 - There is evidence that samples containing some metal compounds e.g. molybdenum, chromium and tungsten can give low results since these compounds are not fully recovered at the temperature of ashing.

NOTE 4 - When phosphorus is absent, barium, calcium, magnesium, sodium and potassium are converted to their sulfates and molybdenum and zinc to their oxides (see NOTE 5). Sulfur and chlorine do not interfere, but when phosphorus is present with metals, it remains partially or wholly in the sulfated ash as metal phosphates.

NOTE 5 - Since zinc sulfate slowly decomposes to its oxide at the ignition temperature specified in the procedure, samples containing zinc may give variable results unless the zinc sulfate is completely converted to the oxide.