A Concern With Biodiesel

Fuel quality control veteran outlines issues related to transport of emerging fuels


One of the major problems for fuel suppliers in assuring jet fuel is free from potential FAME carryover is the lack of widely available testing facilities to measure low-level FAME content. The industry is addressing this issue with a fast track program to develop reliable test methods. But even when these methods are developed, the number of laboratories with the capability to test for FAME content at 5 ppm will be limited.

In the meantime, the approach at Air BP is to follow the guidelines set out in Joint Inspection Group (JIG) Bulletins 15, 16, and 21. We are assessing the potential risk of FAME carryover in all our supply chains and are conducting focused testing. Where investigations suggest that there could be a potential risk of FAME carryover in jet fuel supplies at very low levels, existing and well-established quality assurance procedures are adopted to ensure bulk contamination is below industry-accepted limits. We have adopted these procedures to ensure that all supplies contain less than the current 5ppm max FAME limit.

Industry reaction
The situation is very dynamic and industry is actively working to manage this issue. We are contributing to the development of new test methods and to an industry program that is seeking approval from the aero engine and airframe manufacturers for up to 100 ppm of FAME in jet fuel. Based on existing test results, 100 ppm represents a realistic and achievable level but the approval process will take at least 12 months. In the interim we are working with the OEMs to agree on an emergency protocol to allow fuel with a FAME content greater than 5 ppm to be used to avoid a service disruption at an airport.

Associated risks
The risk of using non-grade dedicated road transports is an issue. While a primary focus has been the risk of FAME contamination during the transport of jet fuel in multi-product pipelines, another serious risk exists in the aviation fuel industry. Some aviation fuel suppliers do not require grade dedicated tanks on road transports. (At a recent road transport carrier forum we asked a group of carriers if they regularly transport biodiesel or other biofuels. Of this group 70 percent answered yes and some stated they transported a grade of biodiesel called B100 which contains 100 percent FAME components.)

It has been our company’s policy that aviation fuel transports be grade dedicated. After the introduction of ultra low sulfur diesel (ULSD) and with the threat of FAME contamination, we are reminding our road transport carriers not to haul jet fuel after biodiesel or ULSD.

We have also advised them that although steam cleaning and drying was an approved procedure prior to hauling aviation fuel, sampling and testing should be done to ensure there is no FAME carryover and that the cleaning procedure was effective. The concern is the fact that FAME is ‘surface active’ and sticks to metal surfaces creating a risk of cross contamination.

To demonstrate this point the JIG Bulletin No. 21 states, “Experience has shown that the practice of three rinses for sample cans does not always remove all traces of FAME and therefore dedicated sample cans and new gloves are simple options to reduce the risk of false alarms.”

Special care must be taken to ensure that if the carrier’s engine driven pump is used to off-load product, it is free of any product remaining from previous use that could contaminate the aviation fuel.

Remember that while the tank may have hauled aviation fuel in previous loads, the pump may have not been used in some time — less than one gallon of B5 in 8,000 gallons of jet fuel will render the fuel off-specification and unfit for use.

An additional risk: ULSD
On the subject of carry-over contamination caused by the use of non-grade dedicated transports, mention needs to be made of the risk posed by the fairly recent introduction of ultra low sulfur diesel — the primary on-road diesel product in the U.S. Not only may ULSD contain up to 5 percent of FAME without any declaration (per ASTM D975), it also contains a lubricity additive found to have the same ‘trail-back’ characteristics as FAME.

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