ISO 3734 Petroleum products - Determination of water and sediment in residual fuel oils - Centrifuge method
WARNING - The use of this International Standard may involve hazardous materials, operations and equipment. This International Standard does not purport to address any 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 laboratory determination of the sum of water and sediment in residual fuel oils using the centrifuge method. With some oils it is difficult to obtain water or sediment contents using this method. When this situation is encountered, ISO 3733 and ISO 3735 should be used.

NOTE - It has been observed that centrifugal methods of determination of water and sediment may, in many cases, give erroneous results. This is especially so when use of a high-speed mixer has been employed to obtain a representative sample. The method is therefore not entirely satisfactory and the amount of water determined is almost always lower than the actual water content.

Significant quantities of water and sediment can cause operational problems in handling equipment and in engines and burners, particularly when the water present contains mineral salts. Design of residual fuel oil treatment facilities, such as filters or centrifuges, is based on a maximum quantity of material to be removed before combustion. Residual fuel oils destined for further refinery processing also require low levels of water and sediment to minimize corrosion problems.

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 3170:1988, Petroleum liquids - Manual sampling.
ISO 3171:1988, Petroleum liquids - Automatic pipeline sampling.
ISO 3733: Petroleum products and bituminous materials - Determination of water - Distillation method.
ISO 3735: Crude petroleum and fuel oils - Determination of sediment - Extraction method.
ISO 4787:1984, Laboratory glassware - Volumetric glassware - Methods for use and testing of capacity.
ISO 5272:1979, Toluene for industrial use - Specifications.
ISO 12937: Petroleum products - Determination of water - Coulometric Karl Fischer method.

3 Principle
Equal volumes of fuel oil and water-saturated toluene are placed in a cone-shaped centrifuge tube. After centrifuging, the volume of the higher-density water and sediment layer at the bottom of the tube is read.