The CPA-4 operatores online and it serves to monitor / maintain product quality for the in-spec production of mixtures such as diesel fuel and heating oil.
The product sample is cooled under defined conditions and it's turbidity is observed. The temperature at which a cloud of paraffin crystals first appears, is know as the CP. The low temperature behaviour of liquid mineral oil products is very important for their usage, as it affects their ability to be pumped, transported and filtered.
The CPA uses a photometric measurement principle. The CP is determined by light scattering caused by finely dispersed colloids which are formed when the product sample in the measuring cell is cooled. The degree of crystallisation of the paraffins in the product correlates with the 'cold energy' delivered to the sample.
The crystals are finely divided particles which scatter and absorb light or other electromagnetic radiation. The scattering depends on the number of particles, the difference in refractive index between the liquid and solids, and the wavelength of the light. The measured CP is the temperature at which a set limit for the scattering is exceeded.
The complete analysis procedure is controlled, monitored and visualised by the Process Analyser Control System (PACS) software.