![]() ![]() Table for Kinematic viscosity / temperature chartĪs the temperature is lowered towards the pour point (lowest flow temperature) there is an increasing upward deviation from the viscosity indicated on the chart. ![]() Figure 7.3aįigure 7.3a Kinematic viscosity temperature chart for burner oil that specified by burner manufacturers for proper atomisation. ![]() From this line can be read the temperature required for any desired viscosity e.g. The approximate viscosity and temperature relationship for any petroleum fuel within these classes, for which viscosity at one temperature is known, can be determined by drawing through the known viscosity / temperature intersection a line parallel to those shown. The four lines on the chart show average viscosity/temperature relationships for fuel of Classes E to H at the maximum viscosity allowed by the specifications. Burner oilsĬlass E-H are residual blended oils for atomizing burners and normally require pre-heating before atomisation. The diagram may be used to construct the viscosity relationship for other oils if the associated viscosity temperature values are known for two points. The scales in the viscosity diagrams are themselves not linear but are adjusted so that the viscosity relationships are linear. This circumstance affects the calculation of the NPSHr (NPSH required) for the pump. Low-sulphurous heating oils have higher pour point temperatures than high-sulphurous ones.Ĭomplex petroleum products, petrol for example, have a vapor pressure range which is dependent upon the most easily flowing components. Pipes which are not heated must be able to be emptied in order to prevent stoppages building up if pumping is interrupted in ambient temperatures below the lowest flow temperature. When considering pumping sluggish, high-viscosity oils with solidifying temperatures near to or above the ambient temperature, (for outdoor installations for example), notice must be taken of the pour point and the installation must be designed so that the pipes and pump can be heated. A few degrees below this temperature, the oil changes to a completely solid form, the solidifying point.īecause of waxing, it is considered that mineral oils can only be handled by pumping at a temperature of at least 10☌ above the pour point. The pour point is reached if the temperature isįurther reduced. This temperature is called the cloud point (cold filter plugging point). When the oil is chilled, it goes cloudy at a certain temperature by reason of the precipitation of paraffin crystals, i.e. Mineral oils transform gradually from the liquid to the solid state, as opposed to other liquids (water, for example, which has an exact freezing point). Cloud point, lowest flow temperature (pour point) and solidifying temperatures In order to assess the needs of a pump installation, the viscosity-temperature relationship must be known and the way the oil behaves with variations in operational temperatures must also be clarified. The viscosity falls as the temperature rises. The viscosity is temperature dependent, oil are flowing more easily when heated. In common with water, they have constant viscosity independent of shear rate and time. The flow capability of oil follows Newton’s law. When pumping oil, the upper and lower operating temperature limits, viscosity, cloud point, lowest flow (pour point), solidifying temperature and the vapour pressure should all be established. Along with mineral oils, we can also reckon such petroleum products as solvents, petrol, kerosene and the like, which should be considered when pumping oil stocks. ![]() Pumping oil with different properties require knowledge of their viscosity and density which varies with the temperature. Oils are classified according to their origins into mineral oils, animal and vegetable oils, but in the context of pumps they can all be treated the same. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |