Pourpoint

The pour point ( engl. "pour" for " pour ", " pouring " within the meaning of ) labeled according to DIN 51597 for a liquid product, the temperature at which it just flows on cooling. The pour point refers to the temperature at which the previously frozen liquid product. According to ISO 3016, the process is certified, which sets out the procedure.

Methods

In the measurement of different cooling baths are used that have been adjusted by 3 ° C lower, respectively. The oil sample is filled into a glass vessel and cooled in the bathrooms. Once the sample has reached the bath temperature, take out the vessel and flips it horizontally. Flowing the oil still, the pour point is not yet reached; the sample in the next colder bath is cooled until the sample stops flowing after removal. A pour point is then added to the bath temperature penultimate used, in which the sample was still fluid. Pour point and pour point are thus 3-6 ° C apart ( see also, however, should be taken into account that this reference refers to another ( DIN ) procedure This reference also clearly describes the distinction between pour point and pour point. ).

In the petrochemical industry often finds the slightly different ASTM standard D97 ( for petroleum products) or D5853 ( for crude oils ) application. And thereby, the sample is cooled, and at each integer multiple of 3 ° C, the flow behavior of the sample is checked by means of tilting of the measurement vessel. Stops flowing the sample, the pour point is reached. As a pour point of the last temperature step is specified in the flow behavior was observed.

A more detailed specification is achieved by using ASTM D5985. Here, the measuring vessel with the sample in a slow rotation ( about 0.1 min -1) is added. A flexibly mounted measuring head immersed in the sample and is moved on reaching the pour point of the abrupt increase in the viscosity of its location, the resulting tilting motion of a sensor triggers. This method provides an accurate approximately 0.1 ° C indicating the pour point. Rounding to the nearest divisible by 3 degrees number of standards-compliant Pour Point ASTM / DIN / ISO can also be obtained.

Applications

The pour point is still set in the valid for heavy fuel oil and marine diesel oil ISO 8217:2005, but no longer used in all other current specifications of main petroleum products such as jet, diesel or fuel oil.

Distinction between

Pour point and pour point are - even in technical descriptions - often used interchangeably, but this is incorrect because the pour point according to DIN 51583 is called. The term freezing point should be related to the pour point and pour point also can not be used because hereby the transition between liquid and crystalline phase is defined and represents a change in the aggregate state. Petrochemical products usually solidify in an amorphous phase (glass).