Jet Fuel Analysis — DEF STAN 91-091 / ASTM D1655 / Jet A-1

What Is Jet Fuel?

Jet fuel analysis is the measurement of aviation fuel's specification parameters. Appearance and cleanliness, density, distillation, flash point, freezing point, kinematic viscosity, net heat of combustion, smoke point, aromatic and sulfur content, copper strip corrosion, thermal stability (JFTOT), existent gum, water separation characteristics (MSEP), electrical conductivity and additive content fall within this scope.

Purpose of Jet Fuel

The purpose is to verify that the fuel does not freeze at high altitude, burns cleanly in the engine, and leaves no deposit in the fuel system. In aviation, fuel quality is directly flight safety.

Which Products Is Jet Fuel Applied To?

Jet A-1 aviation fuel
Jet A and JP-8 derivatives
Sustainable aviation fuel (SAF) blends
Depot and refuelling point samples
Pipeline transfer samples

In Which Sectors Is Jet Fuel Used?

Oil & GasPetrokimyaEnergyAerospace

Standards Related to Jet Fuel

DEF STAN 91-091 (Jet A-1 specification)
ASTM D1655 (aviation turbine fuels)
ASTM D3241 (thermal oxidation stability — JFTOT)
TS EN ISO 2719 / ASTM D56 (flash point)
ASTM D2386 (freezing point)
ASTM D3948 (water separation characteristics — MSEP)
ASTM D2624 (electrical conductivity)
ASTM D7566 (SAF blends)

Jet Fuel Conditions

Sample cleaning: The sample container and the sampling chain must be absolutely clean; contamination invalidates the result
Specimen container: Epoxy coated or stainless steel containers are used; conductivity measurement is affected by the container
Test sequence: Appearance and cleanliness check is the first step
Yeniden sertifikasyon: Defined parameter sets are measured again after transfer and storage

Equipment for Jet Fuel

JFTOT thermal stability apparatus
Freezing point apparatus
Flash point apparatus
MSEP measurement apparatus
Conductivity meter
Membrane filtration and particle counting system

Sample Requirements for Jet Fuel

Sampling determines the validity of the result in fuel analysis: ISO 3170 (manual) and ISO 3171 (automatic in-line) define the sampling rules. The sample must be taken into a clean container of a suitable material, filled with no air gap, and kept cold for volatile products.
The sample container must be suitable for aviation samples; plastic containers are not used
Cleanliness of the sampling chain must be documented
The sampling point, tank and transfer information must be recorded
The sample must be analysed without delay for conductivity measurement

Duration of Jet Fuel

The full specification package takes a few working days. JFTOT and some stability tests require their own durations. Since result speed is critical in aviation, the test sequence is planned accordingly.

Jet Fuel Procedure

1The sample is taken with the cleanliness chain verified.
2Appearance, free water and particulate checks are performed.
3Density, distillation and flash point are measured.
4Freezing point and viscosity are determined.
5The JFTOT thermal stability test is applied.
6MSEP, conductivity and additive analyses are performed.

Jet Fuel Acceptance Criteria

DEF STAN 91-091 and ASTM D1655 define limit values for each parameter; Additionally, JIG (Joint Inspection Group) guides determine which tests will be performed at which stage in the supply chain. Acceptance criteria come from the relevant product specification and vary by season, market and grade. Specification versions are updated; The current limit values to be applied to your product are confirmed in the specification text at the bidding stage.

Evaluation of Results

In aviation fuel, a single out-of-limit parameter prevents use of the batch; other parameters being good does not compensate. MSEP and conductivity values are particularly sensitive and can be affected by the sample container, filter, or additive order; sampling is repeated for suspect results.

Jet Fuel Report

Sample description, tank/line information and sampling chain
Applied specification and its version
Method, result and specification limit for each parameter
Appearance and cleanliness observations
Additive declarations

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Provisions of the aviation authority and the specification owner (MoD, ASTM)
(EU) 2023/2405 ReFuelEU Aviation Regulation

Petroleum, Fuel and Oil Analysis — What Does This Testing Field Cover?

The section below describes the field that the Jet Fuel test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Petroleum, fuel and oil analysis determines whether a fluid meets its specification and how it behaves in use. Standards in this field consist largely of ASTM and EN publications, with a separate method defined for each parameter.

What distinguishes this family is that product specifications are written as PARAMETER LISTS. Specifications such as EN 590 (diesel), EN 228 (petrol), EN 14214 (biodiesel) and ISO 8217 (marine fuels) state for each parameter both the limit and the method by which that limit is to be measured. If the method changes the result may change too; the specification therefore binds the method as well, and the use of an "equivalent method" is possible only where the specification allows it.

On the fuel side, parameters describe three different properties of the product. Physical properties (density, viscosity, distillation curve, pour point, cloud point) determine pumpability and cold weather behaviour. Combustion properties (cetane number, octane number, calorific value) indicate performance in the engine. Contaminant and stability parameters (sulphur, water, sediment, oxidation stability, copper strip corrosion) affect both emissions and storage life.

Oil analysis is carried out for two different purposes and the two must not be confused. Analysis of NEW oil verifies the conformity of the product to its specification: viscosity index, additive content, flash point. Analysis of USED oil, by contrast, is done to read the condition of the machine — elemental analysis shows wear metals (iron, copper, chromium, aluminium), water and fuel contamination point to leaks, and oxidation and acid number determine the remaining life of the oil.

Used oil analysis is therefore a PREDICTIVE MAINTENANCE tool. The trend of samples taken at regular intervals is followed; it is the trend rather than a single result that is meaningful. Iron levels climbing over the course of months allow intervention before a failure occurs.

Marine fuels are the most active sub-body of the field. The global tightening of sulphur limits has brought new blended fuels onto the market; for these fuels stability, compatibility (whether two fuels form deposits when mixed) and catalytic fines content have become critical parameters.

Sampling is part of the result in this family too. A sample taken from the bottom of a tank shows different water and sediment content from one taken from the upper level; in commercial deliveries the sampling point and method are set by contract.

Method groups in this field

Physical properties
Density (oscillating U-tube and hydrometer), kinematic viscosity, distillation, pour and cloud point, flash point.
Combustion properties
Cetane number and cetane index, research and motor octane number, calorific value.
Sulphur and elements
Sulphur by UV fluorescence and XRF; elemental analysis and additive content by ICP.
Stability and corrosion
Oxidation stability, copper strip corrosion, water and sediment, filter blocking tendency.
Composition analysis
Boiling range distribution by gas chromatography, hydrocarbon types (FIA), benzene and aromatics content, fatty acid methyl ester content.
Used oil
Wear metals, contamination (water, fuel, soot), oxidation, acid and base number, change in viscosity.

Commonly confused in this field

The specification binds the method as well; a result measured by a different method may not be accepted for specification conformity.
A single result on used oil is not meaningful; the decision is made on the trend.
The sampling point determines the result; the tank bottom and the upper level show different water and sediment.
The cetane index is a calculated value and is not the same thing as a measured cetane number.
Fuels blended with biodiesel behave differently in terms of storage life and microbial growth; classical diesel parameters are not sufficient.
Mixing marine fuels from different sources can cause deposits; compatibility is assessed separately.

Which decisions these results support

Conformity of a fuel lot to specification and commercial delivery
Predictive maintenance decisions based on used oil analysis
Determining parameters for customs and tax classification
Quality verification after storage, blending and transport
Compliance with sulphur limits under emissions legislation

Related Tests

Frequently Asked Questions About Jet Fuel

Is separate analysis needed for an SAF blend?

SAF blends are assessed under ASTM D7566, and the blended product is expected to meet the D1655 specification. The blend ratio and production pathway used are additionally documented.

Why is the sample container so important?

Plastic containers adsorb the conductivity additive and distort the MSEP result; substances dissolving from the container can also affect the thermal stability result. A sample taken in an unsuitable container gives information about the container, not the fuel.