1. What is API Gravity?

API gravity is a measure of how heavy or light a petroleum liquid is compared to water. Developed by the American Petroleum Institute (API), it's an inverse measure of a petroleum liquid's density relative to water.

2. How Does the Calculator Work?

The calculator uses the API gravity formula:

Where:

• \( SG \) — Specific gravity of petroleum liquid (at 60°F)
• 141.5 and 131.5 — Constants in the API gravity formula

Explanation: The formula converts specific gravity to the API gravity scale, where higher values indicate lighter (less dense) oils.

3. Importance of API Gravity

Details: API gravity is a critical measurement in the petroleum industry used to classify oils as light, medium, heavy, or extra heavy. It affects oil pricing, transportation methods, and refining processes.

4. Using the Calculator

Tips: Enter the specific gravity value (measured at 60°F). The specific gravity must be greater than 0. The calculator will compute the corresponding API gravity.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of API gravity values?
A: API gravity typically ranges from less than 10°API (very heavy oils) to above 50°API (very light condensates). Most crude oils fall between 20°API and 45°API.

Q2: How does API gravity relate to oil quality?
A: Higher API gravity generally indicates lighter oil with higher proportion of valuable light hydrocarbons. Lighter oils typically command higher prices.

Q3: At what temperature should specific gravity be measured?
A: For accurate API gravity calculation, specific gravity should be measured at the standard temperature of 60°F (15.6°C).

Q4: What's the difference between specific gravity and API gravity?
A: Specific gravity is a direct ratio of densities, while API gravity is an arbitrary scale that increases as density decreases, making it more intuitive for oil classification.

Q5: Can API gravity be negative?
A: Yes, API gravity can be negative for substances denser than water (SG > 1.076), though this is rare for petroleum products.