Some people might be interested in how they can perform an API Gravity Test. API stands for the American Petroleum Institute who have been responsible for creating standards used in the Oil and Gas Industry. Standards are very important not only for process applications but also to enable buyers and sellers to compare apples with apples. If you would prefer to watch a video then please view the following presentation which is an excellent student resource.


What you will need to conduct the API Gravity test at a minimum is 

1. Graduated Cylinder
2. API Gravity Hydrometer
3. Thermometer and Hot Plate ( for Crude Oil Testing)

The experiment is normally first conducted at room temperature by novices and is meant to help people understand how heavy or light a liquid is compared to water. If the API Gravity is greater than 10, then it will be lighter and will float on water. If the fluid is less than 10 it is considered to be heavier and thus it will sink.

If you care to go deeper and understand the actual formula and want to move on further from basic concepts then it is expressed very clearly in the following Wikipedia Page which clearly shows how to derive the API Gravity from the density.

api density
API Gravity can also be measured online by speciality instruments called Densitometers. These days it is becoming more important for oil companies to have constant reporting for oil quality including the temperature,  BS&W , mass flow rate and other types of information which enable the business side of the company to determine the value of the product i.e. how pure it really is. The purer the product, the more BTU or Energy it can produce. This is important for buyers and sellers in custody transfer operations.

Not all measurement and analysis activities are going to center around custody transfer metering. There are instances where production companies need to know what is being produced in order to make decisions about the wells they are managing. In these cases there is a choice of examining the fluids using separation technology so that oil, gas and water can be examined and quantified individually. Many companies are also turning to what is commonly referred to as the MPFM. The following video presentation will give you an idea  of a company who is building inline sensing devices to determine the oil fractions online and in realtime.


A decade ago we saw that MPFM technology was something very new and in a kind of testing phase but currently there are now enough units being produced and installed by various manufacturers and more data is being gathered and studied while product development is being continually improved.