Aviation fuel is a mixture of different hydrocarbons. The longer the hydrocarbons are and the higher the molecular weight of the compounds, the more the chemical parameters such as melting point or smoke point differ. These chemical parameters have a considerable influence on the quality of the aviation fuel. An important parameter for quality control used by the aviation fuel manufacturer is the viscosity.
The purity of the aviation fuel in particular is of vital importance for the aviation industry. If the fuel is contaminated with water, ice may form in the fuel tanks and fuel lines at high flying altitudes – a dangerous situation. These ice crystals would disturb or interrupt the flow of fuel to the turbines. At worst this could lead to a failure of the turbines during the flight.
Purity brings safety
The purity of the aviation fuel can be determined via a viscosity measurement. On this subject, standards have been developed and introduced and are recognized around the world. These standards are published and managed by the American Society for Testing and Materials (abbreviation: ASTM). The viscosity measurement of aviation fuel is covered by both ASTM D1655 and ASTM D7566.
When the viscosity is too high
If the viscosity of the aviation fuel is too high, this is a problem for the injection nozzles of the turbines. During fuel injection, the nozzles then have to use more energy to spray the fuel. This shortens the working life of the injection nozzles, which leads to greater maintenance costs and causes re-ignition of the engine in case of a failure during flight. The viscosity also affects the pressure drop in the fuel lines. The higher the viscosity, the higher the pressure drop. As a consequence the fuel pump must work harder to guarantee a constant flow rate so that the turbines can continue working as required.
When the viscosity is too low
If the viscosity is too low, the lack of lubrication in the system can lead to a total failure and cause a crash. The quality of aviation fuel is therefore an essential factor for people and machines in the aviation industry.
The way to safety
Meeting the demands of ASTM D1655 and ASTM D7566 for the certification of aviation fuel requires a viscometer like SVM™ 3001 from Anton Paar. The measurement of viscosity and density on aviation fuel provides the following:
- Density and viscosity values at minus 20 °C and below.For measurements at minus 20 °C SVM™ 3001 requires no additional accessories or other equipment. SVM™ 3001 can reach temperatures down to minus 60 °C by using an external cooler.
- Every batch is checked.Due to the great number of samples this creates it is important to work with small sample volumes. SVM™ 3001 requires a low sample volume of just 1.5 mL and provides quick analysis results.
- Density and viscosity valuesAs SVM™ 3001 has both a viscosity and a density cell, the density measurement does not have to be carried out separately. This measuring cell combination covers the whole measuring range for viscosity, density and temperature. The measuring cells are filled in a single work step.
- Consistent and constant quality of the fuel.SVM™ 3001 is listed in ASTM D1655 and D7566.
Due to the easy operation and useful features of SVM™ 3001 it is now possible to ensure the quality of aviation fuel with little effort for the long term.