ISO 3735 Crude petroleum and fuel oils - Determination of sediment - Extraction method
WARNING - The use of this International Standard may involve hazardous materials, operations and equipment. This International Standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this International Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies a method for the determination of sediment in crude petroleum and fuel oils by extraction with toluene. The precision applies to a range of sediment levels from 0.01 % (m/m) to 0.40 % (m/m), although higher levels may be determined.

NOTE 1 If this International Standard is applied to crude petroleum samples containing significant amounts of salts, an overestimation of the sediment content may be obtained because a proportion of the inorganic salts may be trapped in the extraction thimble. This problem is generally not significant for crude petroleum samples containing less than 0.1 % (m/m) total salts.

NOTE 2 For the purposes of this International Standard, the terms "% (m/m)" and "% (V/V)" are used to represent the mass and volume fractions of materials, respectively.

2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.

ISO 1773:1997, Laboratory glassware - Narrow-necked boiling flasks.
ISO 3170:1988, Petroleum liquids - Manual sampling.
ISO 3171:1988, Petroleum liquids - Automatic pipeline sampling.
ISO 4793:1980, Laboratory sintered (fritted) filters - Porosity grading, classification and designation.
ISO 5272:1979, Toluene for industrial use - Specifications.

3 Principle
A test portion, in a refractory thimble, is extracted with hot toluene until the residue reaches constant mass.