askvity

How to Calculate Specific Gravity of Oil?

Published in Oil Properties 2 mins read

The specific gravity of oil can be calculated using the API gravity through a specific formula.

Understanding Specific Gravity and API Gravity

Before diving into the calculation, it's important to understand these concepts:

  • Specific Gravity (SG): This is the ratio of the density of a substance to the density of a reference substance, usually water (at 4°C). For oil, it indicates how dense it is compared to water.
  • API Gravity: This is an arbitrary scale developed by the American Petroleum Institute (API) to measure the relative density of petroleum liquids. Higher API gravity means the oil is less dense and lighter.

The API to Specific Gravity Conversion Formula

The formula to convert API gravity to specific gravity is:

SG(oil) = 141.5 / (°API + 131.5)

Step-by-Step Calculation

Here's how you use the formula:

  1. Obtain the API Gravity: You'll need the API gravity of the oil you are working with. This is usually provided in the specifications of the oil.

  2. Plug the Value into the Formula: Insert the API gravity value into the formula above.

  3. Calculate: Perform the mathematical operation to get the Specific Gravity.

Example

Let's use the reference information provided:

  • API Gravity (°API) = 35

Using the formula:

SG(oil) = 141.5 / (35 + 131.5)
SG(oil) = 141.5 / 166.5
SG(oil) = 0.8499 (approximately 0.850)

So, for an oil with 35 API gravity, its specific gravity is approximately 0.850.

Quick Recap

Step Action
1. Get API Gravity Find the API gravity of the oil.
2. Insert API into Formula Plug the °API into: SG = 141.5 / (°API + 131.5)
3. Calculate Specific Gravity Solve the calculation.

This is how you can calculate the specific gravity of oil using its API gravity.

Related Articles