To determine the water content of crude oils and petroleum products, three methods can be used:

  • The Karl Fisher coulometric method

This method is used for petroleum products and crude oils – regardless of the pour point. It is commonly used as reference method and is based on a chemical reaction to measure the amount of water present in a sample. (ISO 10337 standard)

  • The Karl Fischer volumetric method

This method is used for crude oils whose pour point is below 18°C. It is commonly used as reference method and is based on a chemical reaction to measure the amount of water present in a sample. (ISO 10336 standard)

It is also used for “white” refined products with the addition of a specific solvent.

  • By distillation (in particular for fuel oils – NFT 60113 standard)


Our laboratory has two means of analysis:

  • Using an electronic hydrometer, we are able to measure a sample’s density at different temperatures, and to convert it according to API tables. The most frequently sought value is the density at 15°C. The electronic hydrometer allows for a constant measurement temperature. The result is thereby more reliable and directly “usable” without conversion. (ISO 12185 standard)
  • An aerometer can also be used to measure density, in cases where the analysis cannot be performed with an electronic hydrometer and for all paraffinic products or too heterogeneous mixtures). (ISO 3675 standard)


Again, two methods can be used:

  • The laboratory has an electronic viscometer (SVM 3000) that allows it to measure the viscosity of the samples to be analyzed. The reference standard for the use of this device is ASTM D7042.
  • The laboratory can also use Cannon-Fenske tubes (ISO 3104 standard) for all products whose viscosity cannot be measured with an electronic viscometer viscosity e viscometer (paraffinic products, too heterogeneous mixtures).


The pour point of a product is the lowest temperature at which the product continues to flow when this temperature is cooled without stirring under standardized conditions (ISO3016 standard).

The SPSE laboratory has a thermostated bath allowing for the sample to be analyzed at different temperatures, thus measuring its pour point.

This number is crucial for determining the storage or transport conditions of hydrocarbons.


For “white” products, such as naphtha or gas oils, color is a quality criterion.

SPSE uses an automatic colorimeter to determine the color of the petroleum products to be analyzed. There are two benchmarks: Saybolt Color NF-ISO 2049 / 1998 and 1500/1996 ASTM Color.