Factors Contributing to Vapor and Gravity Losses

Several factors affect and contribute to vapor and gravity losses in storage tanks: (I) vapor pressure of the product stored, (2) temperature of the product stored. (3) surface area of the product stored. Technical Data used in the field explained in petroleum courses in Rawalpindi.  (4) agitation of the product stored, (5) pressure on the storage tanks, (6) filling losses from the storage tanks, (7) breathing losses from the storage tanks, (8) size of the storage tanks, and (9) color of outside paint or coating. Several, if not all, of these factors usually contribute to the total loss from any one tank or battery.

The true vapor pressure (TVP) of a liquid is the actual pressure it exerts on the vapor space in a container at a given temperature. Water, for example, has a TVP of 1 psi at 100°F and a TVP of 14.7 psi at 212”F, yet it must be kept in a closed container to prevent evaporation. The same is true for crude oil if the TVP is below 14.7 psi. Crudes with a TVP of 10 psi and lower are usually relatively stable in closed-atmospheric storage. Some more details of petroleum courses in Rawalpindi are as under.

Temperature of crude is directly related to its vapor pressure. For example, a crude with a TVP of 8 psi at 50°F will have a TVP of 17 psi at 90°F. The vaporization loss is then approximately doubled at the90°F temperature.

Directly related to the rate of evaporation is the surface area of the crude. Take, for example, two tanks with a capacity of 500 bbl each, one a high 500-bbl tank and the other a low .500-bbl tank. If both are filled one-half full, the high 500 bbl has 0.74 sq ft of surface area exposed per  barrel stored, whereas the low 500 bblhas 1.46 sq ft of surface area exposed per barrel stored. The low SOO-bbl tank then has twice the evaporation rate of the high 500-bbl tank. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join petroleum courses in Islamabad.