of your textbook, and the procedure shown in Figure 9.13 to calculate the viscosity of the blend. For the same blend, we can use the Viscosity Blending Index Numbers in Table 12. Similar to pour point, the viscosity of blends can also be calculates using blending index numbers, or plots developed for this purpose. A serious underestimation of the pour point! Thinking that your diesel fuel has a pour point 8.4 ☏, you may try to start your diesel truck on a 12☏ day, to no avail, not knowing that your fuel tank has a gel, and not a liquid that can be easily pumped to the combustion cylinder. Note that if you would assume linear addition of the pour points, you would calculate a blend pour point as = 0.687x(-6) +0.313x40 = 8.4☏. Using the blend ASTM 50% just calculated (517) and the blending index for the blend from the pour factors (12.47), interpolate/read the pour point of the blend from the table in Figure 9.11, as 15☏.Calculate blend 50% ASTM temperature (linearly additive) of the blend by multiplying the volume fraction with ASTM 50% T of each component and adding them together (0.687x470 +0.313圆20 = 517).Add the pour factors for each component, to calculate the blending index for the blend = 12.47.

For example, the Pour Factor for straight-run gas oil = 0.687 x 6.3 = 4.33.

Multiply PPBI for individual distillates with their respective volume fraction to calculate the Pour Factor.

Straight- run gas oil PPBI =6.3 (using double interpolation), and Hydrotreated heavy gas oil PPBI = 26.

Read pour point blending indices for the two distillates in the table (PPI column) shown in Figure 9.11, and list it in the table (Figure 9.12).

The procedure used to calculate the pour point of the blend (shown Figure 9.12) can be summarized as follows: What would be the pour point of a binary blend that consists of 68.7 % vol of straight-run gas oil and 31.3% vol of hydrotreated heavy gas oil? By arrangement with Chevron Research CompanyĪs an example of using blending indices to calculate the pour point of a blend, consider blending a straight-run gas oil (50% ASTM T = 470☏ and pour point = -6☏) and a hydrotreated heavy gas oil (50% ASTM T = 620☏ and pour point = 40☏).

Viscosity index calculation example