19 Analytical Instrumentation
measurements. ASTM D6378 is widely used in the industry due to its accuracy and reliability, particularly for fuels with high vapor pressures.
• ASTM D5191: Standard Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method) This is a test method that measures the vapor pressure of gasoline and gasoline-oxygenate blends. It is commonly used to ensure compliance with EPA regulations. A sample is placed in a test chamber, and the vapor pressure is measured at 37.8°C (100°F) after a single expansion. This standard is essential for testing reformulated gasoline (RFG) and ensuring it meets regulatory limits on vapor pressure.
• ASTM D5188: Standard Test Method for Vapor-Liquid Ratio Temperature Determination of Fuels (Evacuated Chamber and Piston Based Method) This test method measures the vapor-liquid ratio of fuels at a specifi ed temperature, typically 60°C (140°F). It helps determine the propensity of a fuel to form vapor at high temperatures. The sample is heated to the test temperature, and the volume of vapor formed is measured and compared to the liquid volume. This standard is particularly useful for assessing the performance of fuels in hot climates and ensuring they do not cause excessive vapor lock in engines.
for avoiding fuel vaporization that causes fuel handling issues such as no starts, rough idling, and poor full-throttle acceleration.
V/L has an inverse relationship with vapor pressure – as the vapor pressure of a sample increases, its T(V/L=20) decreases (higher tendency of vapor-lock). The producer’s goal is to blend less expensive, volatile components that increase vapor pressure, making it more profi table, while complying with the V/L specifi cation. The refi nery must perform many V/L measurements daily and therefore needs multiple reliable units.
To meet requirements, fuel labs require the most accurate, precise, and robust laboratory analyzer capable of performing T(V/L=20) measurements according to the piston-based method ASTM D5188.
This analyzer must be easy to operate and maintain, with a fast return on investment (ROI) and low cost of ownership.
Additionally, the manufacturer or vendor must be able to provide continued service and calibration.
MINIVAP VP VISION
Vapor Pressure analyzer The MINIVAP VP Vision from AMETEK Grabner Instruments is designed to meet vapor pressure testing standards. This portable vapor pressure tester offers high precision and a pressure range of 0-2000 kPa. Its closed-system, automatic oiler signifi cantly extends the service life of components such as the piston and valves, reducing the cost of ownership.
Grabner Instruments’ proprietary 2-D calibration ensures accuracy and precision across the full measuring range of the MINIVAP VP Vision. The automatic dead volume calculation program, essential for reliable V/L measurements, ensures precise sample injection volumes.
The analyzer is highly versatile, with the capability to measure both V/L and global vapor pressure methods. Its rapid test program allows automatic performance of dry vapor pressure equivalent (DVPE) and T(V/L = 20) measurements back-to- back.
Controlling the blending process and continuously monitoring allows producers to deliver fuel cost-effectively and high-performing
If a dedicated vapor pressure analyzer fails or is unavailable, the MINIVAP VP Vision can handle vapor pressure measurement tasks until the dedicated analyzer is returned to service, providing system redundancy.
The Challenge of Meeting Vapor
Pressure Testing Standards In back blending, a small amount of high-quality fuel is mixed with a larger quantity of lower-quality fuel to improve its overall quality. This practice allows fuel producers to maximize the use of available resources while ensuring that the fi nal product meets the required specifi cations.
By carefully controlling the blending process and continuously monitoring the quality, producers can deliver fuel that is both cost-effective and high-performing.
Producers of gasoline and gasoline-oxygenate blends operating in the United States must certify their products for vapor-liquid ratio temperature (commonly referred to as ‘V/L’), according to regional and federal regulations.
The industry-standard test method for vapor-liquid ratio temperatures T(V/L=20) is ASTM D5188. This is one of many fuel-characteristic methods that are required within the standard specifi cation for automotive spark-ignition engine fuel (ASTM D4814).
The vapor-liquid ratio temperature indicates the tendency of a fuel to vaporize, within a vehicle’s fuel system.
Modern vehicles have the highest under-hood operating temperatures of all time. This means that V/L is critical
Certifi ed for its robustness and durability, the MINIVAP VP Vision uses Grabner Instruments’ Cockpit™ technology for enhanced networking and global analyzer access. It can measure gasoline, jet fuel, crude oil, LPG, and solvents, maintaining precision across a pressure range of 0-2000 kPa.
Long-term testing demonstrates repeatability of less than 0.13 kPa. The 2D-Calibration (273 points) and precise piston positioning ensure accurate results over the full measuring range. The Sampling Pro™ valve design minimizes cross- contamination, which is crucial when switching from volatile samples to those with a lower vapor pressure.
The analyzer features an intuitive user interface on a 10” touchscreen, simplifying measurement selection and monitoring. Measurement templates can be customized easily, and Grabner Instruments’ Cockpit™ PC software enhances fl exibility by consolidating results from multiple locations.
The MINIVAP VP Vision supports all major VP methods for fuels and LPG. Every analyzer incorporates a speed-adjustable shaker to provide rapid equilibrium for crude oil with fuels and LPG. It is certifi ed for operation in various climates and can withstand vibrations and heavy shocks, making it suitable for mobile laboratories, military applications, and harsh environments.
The Cockpit™ PC software allows automatic recognition and confi guration of multiple instruments worldwide. Through a secure VPN, instruments can be monitored, diagnosed, serviced, and upgraded remotely. The call home function enables easy support from the Grabner Instruments team.
The triple expansion method used by the MINIVAP VP Vision helps users to ensure they are meeting the government regulations as closely to the standard as possible, maximizing profi ts and maintaining fuel quality.
The graph shows relevant ASTM standards and their impact on profi t margins. The indicated ‘give away range’ demonstrates how much potential profi t is given away each year by fuel blenders who adhere to standards that do not meet expectations of the Grabner Instruments triple expansion method.
In addition, the MINIVAP ON-LINE Reid Vapor Pressure (RVP) analyzer can be used for this application. It uses exactly the same principles and methods as the MINIVAP VP Vision, and shares many of the same components, so it can be advantageous to a refi nery to use this analyzer for process monitoring, while the VP Vision is kept for laboratory use.
Up to two different sample streams can be connected to one single MINIVAP ON-LINE analyzer, and this process vapor pressure tester fully complies to the industry relevant ASTM standards for gasoline (ASTM D6378), crude oil (D6377) and LPG (D6897).
Conclusion
In the competitive and highly regulated world of fuel blending, ensuring that blended fuels meet government vapor pressure standards is crucial. Vapor pressure testing methods such as ASTM D6378, ASTM D5191, and ASTM D5188 provide the framework for accurate and reliable measurements.
By leveraging precise vapor pressure measurements, fuel blenders can navigate the complexities of regulatory requirements, optimize their operations for maximum profi tability, and ensure that their products meet the highest standards of quality and safety.
By supplying advanced testing solutions like the MINIVAP VP Vision, Grabner Instruments supports fuel blenders in achieving compliance, optimizing blending processes, and maintaining high-quality fuel standards.
MINIVAP VP Vision is a highly versatile portable vapor pressure tester that demonstrates excellence in engineering
Author Contact Details Ametek Grabner Instruments GmbH • Web:
www.grabner-instruments.com
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