The need for fuel-efficient engines is driven by environmental and economic concerns. One method engine manufacturers are increasingly turning to in order to get more power from a set amount of fuel, is designing the engine to run a high compression.
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The fuel in this design is ‘squeezed’ more by the piston at the point of ignition. Or in any case, this is the intention behind the practice. If the fuel has a low octane rating, it will ignite before the maximum level of compression is reached, nullifying the improved efficiency for which the engine was designed. Instead, a clear and distinct ‘knocking’ sound will be heard, thanks to unwanted combustion within the engine, which can cause engine damage. Therefore, these high-efficiency engines require a high-octane fuel.
In the past, ‘TEL’ or tetraethyl lead has been added to fuel in order to improve the octane rating. However, in the 1990s, it was discovered that leaded fuel caused air pollution which negatively impacted human health, which lead to it being phased out. These days, methylcyclopentadiethyl manganese tricarbonyl, or MMT, has mostly replaced TEL as an octane-boosting additive.
Testing for Manganese in Fuel
The main focus is the manganese content in fuel rather than the MMT content, as the level of manganese (Mn) is what we test for. The current ASTM test method, which is used to measure the level of manganese in fuel, requires atomic absorption spectroscopy – ASTM D3831 – 12(2017). ASTM is revising the test method to bring the standards up to date with current additives used in the industry. ASTM is reviewing the method D5059 (Standard test method for lead in gasoline by X-ray spectroscopy) to extend its scope as well as include the ability to detect manganese in gasoline (ASTM WK62596).
The LAB-X5000 Benchtop Analyzer
The Hitachi High-Tech LAB-X5000 XRF benchtop analyzer is able to measure manganese content in motor gasoline and aviation fuel. The table below summarizes its typical performance for this application:
| . |
. |
| Analyte |
Mn |
| Concentration Range |
0-300 |
| Unit |
mg/1 |
| Standard Error of Calibration |
1.5 |
| Measurement Time |
60 s |
| Limit of detection (3 sigma) |
0.8 |
| Limit of quantification (10 sigma) |
2.5 |
| Mid-range precision (2 sigma) |
2.1 |
Refineries all around the world use the LAB-X in order to measure many elements found in fuels, including sulfur, spanning from the ppm range to several percent. The LAB-X conforms to ASTM D4294, ISO20847 and IP336, as well as meeting the precision requirements of ASTM D5059.
The LAB-X5000 is engineered for accurate and repeatable fuel oil analysis, and incorporates automatic compensation for changes in sample density which arise because of variations in the oil matrix. This means different variations of oils and fuels can be measured on one single calibration rather than matrix-match: an especially useful feature if you are testing samples from different provenances.
For decades, the petroleum industry has trusted the LAB-X range of analyzers. The years of experience have only developed and improved the range to meet wider industry developments. The LAB-X5000 is designed for round-the-clock use, and will help you to ensure that your aviation fuel and gasoline is meeting the right specification for manganese.
This information has been sourced, reviewed and adapted from materials provided by Hitachi High-Tech Analytical Science.
For more information on this source, please visit Hitachi High-Tech Analytical Science.