ASTM D6986-03(2020)

Standard Test Method for Free Water, Particulate and Other Contamination in Aviation Fuels (Visual Inspection Procedures)

SIGNIFICANCE AND USE
5.1 The two procedures in the test method provide rapid methods for field detection of free water and solid contaminants, or any other visually apparent contamination. Uncertain or marginal results by either of these methods would normally result in the performance of methods such as D2276, D5452, or D3240 for quantitative determination of contaminants.  
5.1.1 Particulate determination in appearance tests is sensitive to sampling procedures. The presence of a small number of particles may indicate, for example, that the sample line was not flushed to provide a representative sample. The persistent presence of even a small number of particles, however, may be cause for further investigation depending on the situation.  
5.2 Experience has shown that an experienced tester using a clear bottle can detect as little as 40 ppm of free, suspended water in the fuel. Thus, a fuel rated as clear and bright can still fail lower limits set by quantitative methods. A rater will also have difficulty resolving particles smaller than 40 μm. Smaller particles must be determined by other than visual methods such as D2276, D5452 or chemical field tests listed in Manual 5.5  
5.3 Experience has shown the visual appearance of fuel in a white porcelain bucket to be the most suitable method for the detection of dye contamination or other unusual discoloration. In the U.S., the white porcelain bucket is used to detect the dye.
SCOPE
1.1 This test method covers two procedures for establishing the presence of suspended free water, solid particulate, and other contaminants in aviation gasoline and aviation turbine fuels.  
1.1.1 Both procedures are intended primarily for use as field tests with the fuel at handling temperature.  
1.1.2 Procedure A uses transparent sample containers; Procedure B uses opaque containers.  
1.2 Both procedures are rapid methods for contamination detection and include ratings of haze appearance and particulate presence.  
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2020
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.J0 - Aviation Fuels

Relations

• Refers: ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 01-Jun-2011
• Refers: ASTM D4176-04(2009) - Standard Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)
• Effective Date: 01-Jun-2009
• Refers: ASTM D2276-06 - Standard Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling
• Effective Date: 01-Dec-2006
• Refers: ASTM D5452-06 - Standard Test Method for Particulate Contamination in Aviation Fuels by Laboratory Filtration
• Effective Date: 01-Dec-2006
• Refers: ASTM D2276-05 - Standard Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling
• Effective Date: 01-Dec-2005
• Refers: ASTM D5452-05 - Standard Test Method for Particulate Contamination in Aviation Fuels by Laboratory Filtration
• Effective Date: 01-Dec-2005
• Refers: ASTM D3240-05 - Standard Test Method for Undissolved Water In Aviation Turbine Fuels
• Effective Date: 01-Nov-2005
• Refers: ASTM D3240-11 - Standard Test Method for Undissolved Water In Aviation Turbine Fuels
• Effective Date: 01-Nov-2005
• Refers: ASTM D4176-04 - Standard Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)
• Effective Date: 01-Nov-2004
• Refers: ASTM D4176-04e1 - Standard Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)
• Effective Date: 01-Nov-2004
• Refers: ASTM D4176-93(1997) - Standard Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)
• Effective Date: 10-Feb-2002
• Refers: ASTM D4176-02 - Standard Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)
• Effective Date: 10-Feb-2002
• Refers: ASTM D5452-00 - Standard Test Method for Particulate Contamination in Aviation Fuels by Laboratory Filtration
• Effective Date: 10-Jun-2000
• Refers: ASTM D2276-00 - Standard Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling
• Effective Date: 10-Jun-2000
• Refers: ASTM D4057-95(2000) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 10-Apr-2000

Overview

ASTM D6986-03(2020) is the internationally recognized standard test method developed by ASTM International for detecting free water, particulate, and other visually apparent contamination in aviation fuels. Using straightforward visual inspection procedures-including transparent and opaque sample container methods-this standard enables rapid, field-based identification of water, solid contaminants, and other anomalies in aviation gasoline and turbine fuels. By relying on clear procedures and rating systems for appearance, ASTM D6986 helps ensure the integrity and performance of aviation fuels at critical points in the fuel supply chain.

Key Topics

• Visual Inspection Procedures

  • Procedure A uses transparent sample containers for viewing haze, water, and particulates.
  • Procedure B uses opaque containers (white bucket method) for optimal detection of unusual coloration, dye, or sediment.

• Field Detection and Rapid Assessment

  • Enables on-the-spot evaluation at handling temperature, suitable for fuel farms, airport fueling stations, and transportation nodes.
  • Can detect as little as 40 ppm of suspended water with experienced personnel.

• Ratings and Reporting

  • Provides guidelines for classifying samples as “clear and bright” or assigning haze/contaminant ratings.
  • Utilizes bar charts and rating guides for consistent, non-quantitative reporting.
  • Results are a key trigger for more quantitative laboratory tests if contamination is suspected.

• Contaminant Recognition

  • Focuses on the identification of free water, particulate matter, color changes, microbial growth, dye contamination, and other anomalies.
  • Sample appearance guides help determine when to escalate to further analysis.

Applications

ASTM D6986-03(2020) delivers practical value across the aviation fuel industry by supporting:

• Routine Quality Control

  • Field inspection of aviation fuels during receiving, storage, and before delivery to aircraft.
  • Early detection of contamination events to prevent safety incidents and equipment damage.

• Compliance with International Standards

  • Alignment with best practices for aviation fuel handling as recognized by international and regulatory authorities.
  • Provides documentation and traceability for fuel quality assurance programs.

• Fuel Supply Chain Safety

  • Used by fuel suppliers, airport authorities, maintenance teams, and regulatory inspectors to maintain high fuel quality standards.
  • Visual inspection is embedded in operational checklists before fueling aircraft.

• Support for Further Testing

  • Clarifies when additional quantitative testing (using methods such as ASTM D2276, D5452, D3240) is necessary based on visual findings.

Related Standards

• ASTM D2276 - Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling
• ASTM D5452 - Test Method for Particulate Contamination in Aviation Fuels by Laboratory Filtration
• ASTM D3240 - Test Method for Undissolved Water in Aviation Turbine Fuels
• ASTM D4057 - Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4176 - Test Method for Free Water and Particulate Contamination in Distillate Fuels (Visual Inspection Procedures)

Practical Value

Following ASTM D6986-03(2020) helps organizations minimize fuel contamination risks by providing a fast, effective field test for aviation gasoline and turbine fuels. Its procedures reinforce operational safety, enable ongoing quality monitoring, and offer clear action points for fuel handlers and inspectors throughout the aviation sector. This standard, built on internationally recognized principles, is essential for improving aviation fuel reliability, protecting engines, and supporting global fuel quality compliance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6986 − 03 (Reapproved 2020)
Standard Test Method for
Free Water, Particulate and Other Contamination in Aviation
Fuels (Visual Inspection Procedures)
This standard is issued under the fixed designation D6986; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Fuel quality is paramount in aviation fuels because of their critical application. Many successive
types of inspections are conducted to ensure quality protection. Rapid, visual inspections carried out
at various locations in the fuel supply system are a critical part of the inspection program. Experience
hasshownthatsubjectiveevaluationssuchasdescribedbythistestmethodformaneffectivefieldalert
system that is backed by other, more quantitative tests.
The present test method duplicates much of Test Method D4176, a test method applicable to all
distillate fuels. However, the present test method also includes field methods applicable especially to
aviation fuels, and is therefore published as a separate test method.
1. Scope 2. Referenced Documents
1.1 This test method covers two procedures for establishing
2.1 ASTM Standards:
the presence of suspended free water, solid particulate, and
D2276 Test Method for Particulate Contaminant in Aviation
other contaminants in aviation gasoline and aviation turbine
Fuel by Line Sampling
fuels.
D3240 Test Method for Undissolved Water In Aviation
1.1.1 Both procedures are intended primarily for use as field Turbine Fuels
D4057 Practice for Manual Sampling of Petroleum and
tests with the fuel at handling temperature.
Petroleum Products
1.1.2 Procedure A uses transparent sample containers; Pro-
D4176 Test Method for FreeWater and Particulate Contami-
cedure B uses opaque containers.
nation in Distillate Fuels (Visual Inspection Procedures)
1.2 Both procedures are rapid methods for contamination
D5452 Test Method for Particulate Contamination in Avia-
detection and include ratings of haze appearance and particu-
tion Fuels by Laboratory Filtration
late presence.
2.2 ASTM Adjuncts:
1.3 The values stated in SI units are to be regarded as the
ADJD417601 Distillate Fuel Bar Chart
standard. The values given in parentheses are for information
ADJD417602 Distillate Fuel Haze Rating Standard
only.
3. Terminology
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.1 Definitions of Terms Specific to This Standard:
ization established in the Decision on Principles for the
3.1.1 aviation fuels, n—as used in this standard, the term
Development of International Standards, Guides and Recom-
includes both aviation gasoline and aviation turbine fuels.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
This test method is under the jurisdiction of ASTM Committee D02 on Standards volume information, refer to the standard’s Document Summary page on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of the ASTM website.
Subcommittee D02.J0 on Aviation Fuels. Available from ASTM International Headquarters. Order Adjunct No.
Current edition approved May 1, 2020. Published June 2020. Originally ADJD417601.
published in 2003. Last previous edition approved in 2016 as D6986 – 03 (2016). Available from ASTM International Headquarters. Order Adjunct No.
DOI: 10.1520/D6986-03R20. ADJD417602.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6986 − 03 (2020)
3.1.2 clear and bright, adj—a condition in which the fuel 5.1.1 Particulate determination in appearance tests is sensi-
contains no visible water drops or particulates and is free of tivetosamplingprocedures.Thepresenceofasmallnumberof
haze or cloudiness. particles may indicate, for example, that the sample line was
not flushed to provide a representative sample. The persistent
3.1.3 free water, n—water in excess to that soluble in the
presence of even a small number of particles, however, may be
fuel at the temperature of the test and may appear in the fuel as
cause for further investigation depending on the situation.
a haze, cloudiness, droplets, or water layer.
5.2 Experience has shown that an experienced tester using a
3.1.4 solid particulates, n—small solid or semi-solid
clear bottle can detect as little as 40 ppm of free, suspended
particles, sometimes referred to as silt or sediment, present in
water in the fuel.Thus, a fuel rated as clear and bright can still
a fuel as the result of contamination by airborne dusts,
fail lower limits set by quantitative methods. A rater will also
corrosion by-products, or wear products.
have difficulty resolving particles smaller than 40 µm. Smaller
particlesmustbedeterminedbyotherthanvisualmethodssuch
4. Summary of Test Method
as D2276, D5452 or chemical field tests listed in Manual 5.
4.1 The test method describes two types of sampling con-
5.3 Experience has shown the visual appearance of fuel in a
tainers for evaluating the appearance of aviation fuel samples.
white porcelain bucket to be the most suitable method for the
Procedure A covers transparent sample containers, including
detection of dye contamination or other unusual discoloration.
the open jar and the closed circuit sampler, while Procedure B
IntheU.S.,thewhiteporcelainbucketisusedtodetectthedye.
uses opaque containers such as the white bucket.
4.2 Intheopenjarprocedure,aminimumof750 mL(24 oz)
6. Apparatus
of fuel is placed into a clear one litre (1 qt) container and
6.1 Cylindrical Clear Container, such as:
examined visually. The jar is then closed and the sample is
6.1.1 Clear Container, with lid, capable of holding 750 mL
swirled and examined for visual sediment and water at the
(nominal 1 U.S. qt) of fuel and having a diameter of 100 mm
bottom of the vortex.Additionally, fuel clarity may be rated by
610 mm(4 in. 60.4 in.).Thereshouldbenogasketinthelid.
placing a standard bar chart behind the sample and comparing
6.1.2 Closed Circuit Sampler, holding about 4 L(1 gal U.S.)
its visual appearance with the standard haze rating photo-
of fuel and being permanently mounted to receive fuel from a
graphs. The presence or absence of free water and of particu-
fuel line or a storage tank and having inlet and outlet valves to
lates is reported.
control filling and emptying of the container. The sampler base
4.3 In the closed circuit sampler procedure, approximately
is normally conical and incorporates the fuel inlet and outlet.
3500 mL(0.9 U.S. gal) of fuel is placed into the sampler and is
The fill port is designed to cause the fuel to swirl around the
examined for clarity and for visual sediment or water droplets
sides of the clear glass tube. The circuit sampler may also
on the bottom of the sampler.Additionally, fuel clarity may be
contain hydrometer and chemical water detection ports.
rated by placing a standard bar chart behind the sample and
6.2 Appearance Card and Photographs:
comparing its visual appearance with the standard haze rating
6.2.1 Paper Card (Bar Chart), laminated in clear plastic
photographs. The presence or absence of free water and of
having five parallel lines of different widths (see ASTM
particulates is reported.
adjunct ADJD417601).
4.4 In the white bucket procedure fuel to a depth of
6.2.2 Appearance Photographs, a series of standard photo-
approximately 15 cm (6 in.) is collected in a white porcelain
graphs of the bar chart through a series of samples of different
coated or stainless steel bucket. The sample is examined for
haze levels, numbered from one through six. Photograph No. 1
solids or sediment, or both, on the bottom of the bucket.
is the clearest, while No. 6 represents the densest haze (see
Sample clarity can be checked by the appearance of a small,
ASTM adjunct ADJD417602). A fuel sample rated clear and
shiny coin on the bucket’s bottom. If the fuel is dry, the raised
bright will have a rating of “one.”
letters on the coin should be easily readable. The amount of
6.2.2.1 The differences between these haze levels are arbi-
sediment can be described by a letter category using a rating
trary and are not intended to represent equivalent increases in
guide.
suspended water content or particulates. It is essential,
therefore, that only the proper approved bar charts and photo-
4.5 In both procedures, the sample is inspected for color or
other unusual appearance. graphs be used.
6.3 Opaque Sample Containers:
4.6 Field inspection procedures are performed immediately
after sampling at fuel handling temperature conditions. 6.3.1 White Bucket, a circular bucket with straight but
non-parallel sides and a flat bottom and a minimum capacity of
5. Significance and Use 7.5 L (2.0 U.S. gal) and approximately 20 cm (8 in.) high,
either coated with white porcelain enamel or made of stainless
5.1 The two procedures in the test method provide rapid
steel. Porcelain coatings must be free of dark spots, chips, or
methods for field detection of free water and solid
other surface damage, most particularly on the bottom of the
contaminants, or any other visually apparent contamination.
bucket. Stainless steel buckets shall be made of a rust-resistant
Uncertain or marginal results by either of these methods would
normally result in the performance of methods such as D2276,
D5452,or D3240 for quantitative determination of contami-
Manual 5, Aviation Fuel Quality Control Procedures, 2nd Ed., ASTM
nants. International, W. Conshohocken, PA, 1995.
D6986 − 03 (2020)
steel and have a polished internal surface. The white porcelain examine the bottom of the vortex for particulate matter and
bucket should be used for the optimum detection of unusual water droplets. Also look for brown slime or a water layer on
coloration. the bottom of the container. Record the particulate and water
appearance rating of the sample using the ratings in Tables 1
NOTE 1—A quantitative description of acceptable white color is in
and 2. Record the appearance of any other contaminant using
preparation.
Table 3 as a guide. Record the ambient temperature.
NOTE 2—Buckets made of white, hard plastic have been found to stain
a yellow color over time, which can make it difficult to observe a haze or
8.1.1.2 Use of Bar Chart and Photographs—Immediately
color changes. The use of plastic containers is also discouraged unless
on drawing a sample, place the container into a well-lighted
provision is made for bonding such containers to the filling line.
area, avoiding light reflections on the front of the container as
6.4 Color and Particle Assessment Rating Guide:
much as possible. Place the bar chart directly behind the
6.4.1 This guide contains both a series of photographs of
container, with the lines toward the container and parallel with
particulates of differing concentrations, each having a different
the bottom of the container.The narrowest line should be at the
letter rating, and a series of color photographs for rating filter
bottom of the container. Directly facing the container and bar
membranes obtained by Test Methods D2276. For this test
chart, compare the appearance of the bar chart through the
method, only the particle rating scale is used. The particle
sample with the standard photogr
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