P
Reid Vapor Pressure
Reid vapor pressure is an empirical test that measures the pressure in pounds per square inch (psi) exerted by the vapors or light components of crude oil or petroleum product in a closed vessel at a temperature of 100°F (38°C).
A high Reid vapor pressure of crude oil indicates the presence of light products in it, and during processing, they will be burned in the torch if there is no proper recovery system. In the case of an internal combustion engine, an excess of vapor pressure can lead to vapor lock, which can block the flow of gasoline.
Freezing Point
It is the temperature at which crystals formed during the cooling of a sample of a product completely disappear when the temperature is raised under controlled conditions.
Pour Point
The temperature at which a liquid ceases to flow when cooled due to the precipitation of solid paraffin crystals.
The runoff temperature is very important, since in case of discharge of paraffinic crudes using marine terminals with submarine lines of a certain length, the temperature of the crude can drop below the runoff point, causing wax or solid paraffin to be deposited on the lines, preventing flow.
Flash Point
The flash point is the minimum temperature at which the vapors of a product ignite or detonate momentarily when a flame is applied under controlled conditions. It represents the maximum temperature at which a product can be stored or transported safely.
R
Carbon Residue
It is the weight of the residue remaining after the combustion of a fuel sample. It indicates the ease with which a heavy fuel can produce particles during combustion.
S
Salt
Crude oil contains salt (NaCl), which comes from oil fields or the seawater used for ballasting oil tankers. It is necessary to remove the salt using desalting equipment before the crude oil enters the atmospheric distillation unit to prevent corrosion at the top of the atmospheric tower. Salt decomposes to produce hydrochloric acid. It is expressed in grams of salt per cubic meter of crude oil.
T
Autoignition Temperature
Autoignition temperature is the temperature at which some products spontaneously ignite on contact with air (without a flame), probably due to the heat produced by slow oxidation, which accumulates, raising the temperature to the ignition point. Fortunately, distillates from petroleum have very high autoignition temperatures and are, therefore, difficult to achieve. In gasoline, it is 842°F (450°C). Gasoline-soaked rags, on the other hand, ignite easily, potentially causing fires and must be disposed of properly.