ASTM D5191

Standard Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method).

Get more information about the standard at  ASTM D5191-22.

eraspec

Spectral Fuel Analysis
The FTIR spectral fuel analyzer ERASPEC

The FTIR spectral fuel analyzer.

eravap

Vapor Pressure Testing
The vapor pressure tester ERAVAP
fully compliant with ASTM D5191

The all-round vapor pressure tester.

eravap for crude oil

Vapor Pressure Testing
The vapor pressure tester ERAVAP for crude oil and an eralytics Manual Piston Cylinder in front of it.
fully compliant with ASTM D5191

The crude oil vapor pressure tester.

eravap for lpg

Vapor Pressure Testing
The vapor pressure tester ERAVAP and a Floating Piston Cylinder in front of it.
fully compliant with ASTM D5191

The LPG vapor pressure tester.

eravap online

Vapor Pressure Testing
The online vapor pressure tester ERAVAP ONLINE

The process vapor pressure tester.

ASTM D5191 specifies a procedure for measuring the vapor pressure of petroleum products, including gasoline, gasoline-oxygenate blends, and other volatile fuels. Vapor pressure is a crucial property for fuel performance, safety, and environmental compliance, influencing fuel evaporation, engine performance, and emissions. This method provides accurate, rapid results using a piston based mini vapor pressure analyzer, making it a preferred choice for quality control and regulatory compliance.

Details

ASTM D5191 is a method for determining the vapor pressure of fuels at a specified temperature.  The test is conducted using a piston based mini vapor pressure analyzer, which operates under controlled conditions to provide precise and reproducible measurements. The sample must be chilled and air-saturated to give accurate results. After introducing the sample, the valves of the

instruments are closed and the piston is expanded to generate a vacuum in the headspace above the sample. Due to the volatility of the sample, the vapor pressure of the sample can be detected in the head space after thermal equilibrium.

ASTM D5191 is advantageous because it requires a smaller sample volume and operates more quickly than traditional vapor pressure methods like ASTM D4953. However, due to the requirement of sample preparation, it is prone to operator bias, a significant disadvantage compared to more modern vapor pressure methods like ASTM D6378.  

Vapor pressure data from ASTM D5191 is used to evaluate seasonal fuel volatility, prevent vapor lock, ensure safety during transportation and storage, and limit evaporative emissions in accordance with environmental standards such as those set by the U.S. Environmental Protection Agency (EPA).

Industries & Applications

ASTM D5191 is widely used in the following industries:

  • Petroleum refining: Ensures fuel meets regional and seasonal volatility specifications
  • Fuel blending facilities: Monitors ethanol-gasoline blends to comply with emissions and performance standards
  • Automotive industry: Validates that fuels meet performance and emissions criteria for modern engines
  • Environmental agencies: Enforces compliance with fuel volatility regulations to control evaporative emissions
  • Fuel distribution and storage: Maintains safety and stability during transportation and storage under varying conditions