Standard Test Method for Measurement of Thermal Stability of Aviation Turbine Fuels under Turbulent Flow Conditions (HiReTS Method) <a href="#fn00002"></a>
SIGNIFICANCE AND USE
The thermal stresses experienced by aviation fuel in modern jet engines may lead to the formation of undesirable and possibly harmful insoluble materials, such as lacquers, on heat exchangers and control surfaces, that reduce efficiency and require extra maintenance.
Aircraft fuel systems operate mainly under turbulent flow conditions. Most large-scale realistic test rigs operate in the turbulent flow regime but fuel volumes are very large and test times are very long.
This test method tests fuel under turbulent flow (high Reynolds number) conditions, and it gives a quantitative result under standard operating conditions of 65 or 125 min. Continuous analysis of results during the test allows performance of the fuel to be monitored in real time thus enabling the test time to be reduced manually or automatically, if required.
The results of this test method are not expected to correlate with existing test methods for all fuels, since the test methods and operating conditions are different (see Appendix X2).
SCOPE
1.1 This test method covers a laboratory thermal process, using a specified apparatus for measuring the tendencies of aviation turbine fuels to deposit insoluble materials and decomposition products, such as lacquers, within a fuel system. This test method provides a quantitative result for fuel under turbulent flow conditions in 65 or 125 min.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D6811–02 (Reapproved 2007)
Designation: 482/02
Standard Test Method for
Measurement of Thermal Stability of Aviation Turbine Fuels
,
1 2
under Turbulent Flow Conditions (HiReTS Method)
This standard is issued under the fixed designation D6811; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E128 Test Method for Maximum Pore Diameter and Per-
3 meability of Rigid Porous Filters for Laboratory Use
1.1 This test method covers a laboratory thermal process,
using a specified apparatus for measuring the tendencies of
3. Terminology
aviation turbine fuels to deposit insoluble materials and de-
3.1 Definitions of Terms Specific to This Standard:
composition products, such as lacquers, within a fuel system.
3.1.1 capillary tube, n—acoatedresistivelyheatedstainless
This test method provides a quantitative result for fuel under
steel tube through which fuel is pumped and controlled to give
turbulent flow conditions in 65 or 125 min.
a predefined constant fuel exit temperature.
1.2 The values stated in SI units are to be regarded as the
3.1.2 deposits, n—oxidativeproducts,suchaslacquers,laid
standard.
downpredominantlyatthefuelexitend(hottest),ontheinside
1.3 This standard does not purport to address all of the
of the heated capillary tube.
safety concerns, if any, associated with its use. It is the
3.1.3 HiReTS, n—high Reynolds number thermal stability.
responsibility of the user of this standard to establish appro-
3.1.4 HiReTS Peak (P) number and Total (T) number,
priate safety and health practices and determine the applica-
n—the quantitative results of the test.
bility of regulatory limitations prior to use.
3.1.5 tubeways, n—plastic and metal tubes through which
2. Referenced Documents fuel flows during cleaning and the test.
2.1 ASTM Standards:
4. Summary of Test Method
D4057 Practice for Manual Sampling of Petroleum and
4.1 Fuel is pumped, at pressure, through an electrically
Petroleum Products
heated capillary tube at a constant rate. The heating of the
D4177 Practice for Automatic Sampling of Petroleum and
capillary tube is controlled to maintain a constant fuel tem-
Petroleum Products
perature of 290 6 3°C at the exit of the capillary tube.Aflow
D4306 Practice for Aviation Fuel Sample Containers for
rate of greater than 20 mL/min and the specified capillary bore
Tests Affected by Trace Contamination
oflessthan0.300mmensuresthatturbulentflowismaintained
(see Appendix X1) within the capillary. The formation of
This test method is under the jurisdiction of ASTM Committee D02 on
lacquers and fuel degradation products act as a thermal
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee
insulator between the cooler fuel and hotter capillary tube,
D02.14 on Stability and Cleanliness of Liquid Fuels.
resulting in an increase in temperature of the capillary tube
Current edition approved Nov. 1, 2007. Published January 2008. Originally
approved in 2002. Last previous edition approved in 2002 as D6811–02. DOI: which is measured at a number of positions by a contactless
10.1520/D6811-02R07.
pyrometer. The HiReTS Total (T) number is displayed during
This test method is being jointly developed with the Institute of Petroleum,
andattheendofthetest.TheHiReTSPeak(P)numbercanbe
where it is designated IP 482.
determined from analysis of the results.
This process is covered by a patent. Interested parties are invited to submit
information regarding the identification of an alternative(s) to this patented item to
the ASTM Headquarters. Your comments will receive careful consideration at a 5. Significance and Use
meeting of the responsible technical committee, which you may attend.
4 5.1 The thermal stresses experienced by aviation fuel in
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
modern jet engines may lead to the formation of undesirable
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
and possibly harmful insoluble materials, such as lacquers, on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6811–02 (2007)
heat exchangers and control surfaces, that reduce efficiency 7.2 Trisolvent, for cleaning sampling vessels. (Warning—
and require extra maintenance. Each of the components and the trisolvent is flammable;
5.2 Aircraft fuel systems operate mainly under turbulent harmful if inhaled; irritating to skin, eyes and mucous mem-
flow conditions. Most large-scale realistic test rigs operate in branes.) It consists of equal volumes of the following:
the turbulent flow regime but fuel volumes are very large and 7.2.1 Acetone, CH ·CO·CH ,technicalgrade,95%purity.
3 3
test times are very long. 7.2.2 Toluene, C H·CH , technical grade, 95% purity.
6 5 3
5.3 This test method tests fuel under turbulent flow (high 7.2.3 Propan-2-ol, (CH ) ·CH·OH, technical grade, 95%
3 2
Reynolds number) conditions, and it gives a quantitative result purity.
under standard operating conditions of 65 or 125 min. Con- 7.3 Cleaning Solvent, technical grade, 95% purity, for
tinuous analysis of results during the test allows performance cleaning sampling vessels. (Warning—Extremely flammable;
of the fuel to be monitored in real time thus enabling the test harmful if inhaled.) It consists of one of the following:
time to be reduced manually or automatically, if required. 7.3.1 2-methylpentane.
5.4 The results of this test method are not expected to 7.3.2 3-methylpentane.
correlate with existing test methods for all fuels, since the test 7.3.3 2,2,4-trimethylpentane.
methods and operating conditions are different (see Appendix 7.4 Drying Components,todrytheairusedforaerationand
X2). to indicate the absorption of water by changes from blue to
pink color. Use a mix, by volume or weight of the following:
6. Apparatus (see Annex A1)
7.4.1 Calcium Sulfate Anhydrous Powder, CaSO (97%).
6.1 General—(See Fig.A1.2.) Fuel contained in the sample
7.4.2 Cobalt Chloride Anhydrous, CoCl (3%) granules.
vessel is drawn through the sample filter by a pump. The 7.5 Air, 1.5 L/min for aeration of the test sample.
temperature of the fuel is checked by the input fuel electronic
thermometer.Thefuelispumpedataconstantrate,atpressure
8. Sampling and Sample Containers
set by the back pressure valve, through an electrically heated
8.1 Obtain samples for testing in accordance with Practices
capillary tube which has a blackened outer surface to give a
D4057 or D4177, with the following additional requirements:
high thermal emissivity. The heating of the capillary tube is
8.1.1 Containers shall be fully epoxy lined or made of
controlledtomaintainaconstantfueltemperature,asmeasured
polytetrafluoroethylene (PTFE). See Note 2 and Practice
by the capillary exit electronic thermometer, at the exit of the
D4306.
capillary tube. The waste fuel is then cooled to a temperature
8.1.2 Prior to sampling, all containers and their closures
oflessthan20°Caboveambient,asmeasuredbythewastefuel
shallberinsedatleastthreetimeswiththefuelbeingsampled.
electronic thermometer, before being discharged to a waste
8.1.3 Test samples as soon as possible after sampling.
container.Duringthetest,thetemperatureoftheoutsideofthe
NOTE 2—Testmethodsformeasuringthermalstabilityareknowntobe
capillarytubeisscanned,checkedandrecordedevery5minat
sensitive to trace contamination during the sampling operation and from
12 points along the exit end of the capillary tube using a
samplecontainers.Newcontainersarerecommended,butwhenonlyused
contactless pyrometer which is located on a computer-
containers are available, a thorough rinse with trisolvent (see 7.2)
controlled elevating platform.
followed by cleaning solvent (see 7.1 and 7.3), and drying with a stream
5 5
6.2 The thermal stability apparatus and capillary tube is
of air is recommended.
specified in detail in Annex A1.
8.2 Aeration of Test Sample—Aerate the test sample, with
6.3 Sparger, of porosity 40 to 80 µm, which allows an air
dry air, through the sparger at an air flow rate of 1 to 2 L/min
flow of approximately 1.5 L/min.
for 10 min.
NOTE 1—TheporosityofthespargercanbecheckedusingTestMethod
8.3 Sample Size—Standardoperatingconditionsare:3Lfor
E128.
13 scans (65–min test) and 5 L for 25 scans (125-min test).
6.4 Sample Filter, 20-µm stainless steel.
6.5 Aeration Dryer, glass or other suitable transparent
9. Preparation of Apparatus
material,minimumheight250mm,minimumdiameter50mm,
9.1 Prepare the instrument for operation in accordance with
filled with dry calcium sulfate and cobalt chloride (see 7.4),
the manufacturer’s instructions. (Warning—Installing and re-
whichisusedinconjunctionwithanairsupplyandthesparger
moving the capillary tube may result in exposure to fuel or
(see 6.3) to aerate the test sample.
solvent.Itisrecommendedthatimpermeableglovesandsafety
glasses are worn.)
7. Reagents and Materials
9.2 Remove the sample filter and inlet tubing and clean by
7.1 Heptane, CH ·(CH ) ·CH ,technicalgrade95%purity,
3 2 5 3
rinsing with heptane and then by back flushing with heptane,
for cleaning the apparatus tubeways, and sampling vessels.
and then refit.
(Warning—Extremely flammable; harmful if inhaled.)
9.3 SettheinstrumentinaccordancewithTable1andcheck
thatthecorrectstandardoperatingconditionsareinaccordance
with Section 10.
The equipment, as listed in the research report being prepared, was used to
develop the precision statement. The apparatus and capillary tubes described in
9.4 Inspect 40 mm of the blackened section at both ends of
AnnexA1arebothsuppliedbyStanhope-Seta,Chertsey,SurreyKT168AP,UK.To
the capillary tube and reject the tube if any scratches, pinholes
datenootherequipmenthasdemonstratedthroughASTMinterlaboratorytestingthe
or cracks are deep enough to expose the capillary tube’s bright
ability to meet the precision of this test. This is not an endorsement or certification
by ASTM. A research report is being prepared. metal surface.
D6811–02 (2007)
TABLE 1 Standard Instrument Settings
12.3 Visually check the system for leaks. If a leak is found,
abort the test and vent the system by using the bypass valve.
NOTE 1—Tolerances for the instrument settings are given inAnnexA1.
Tighten or replace any leaking fittings if necessary and repeat
NOTE 2—Thedatumpositionisthebottomofthetopbusbarconnector.
See Fig. A1.3. 12.3.
NOTE 3—Touching the blackened section of the capillary tube should
12.4 Closethecapillarytubeenclosuredoor,ensurethatthe
be avoided, especially within 50 mm of each end.
bypass valve is set to TEST, and commence heating the
Distance from datum (see Fig. A1.3) to the first measurement posi- 1mm
capillary tube.
tion
Number of capillary tube temperature measurement positions 12
NOTE 6—The pyrometer commences measuring the temperature of the
Distance between individual measuring points 2.5 mm
capillary tube at the required positions when the fuel exit temperature,
Rate of scanning all capillary tube temperature measurement posi- 12/h
from the capillary tube, has stabilized to the prescribed value.
tions
12.5 Attheendofthetestremovethesamplefilterandinlet
tubing and clean by rinsing with heptane and then by back-
9.5 Commence the pre-test by installing a new capillary flushing with heptane, and then refit. Immerse the input tube
andsamplefilterinheptaneandcleanthesysteminaccordance
tube and carrying out the following in accordance with the
with the manufacturer’s instructions. When this procedure has
manufacturer’s instructions.
9.6 Immerse the input tube and sample filter in heptane. been completed, vent the system using the bypass valve.
9.7 Clean the tubeways with heptane and reset the bypass
NOTE 7—Heptane draining out of the apparatus can be avoided by
valve to TEST.
leaving a capillary tube installed or by capping the upper and lower
9.8 Visually check the system for leaks. If a leak is found,
unions, and ensuring that the bypass valve is in the TEST position.
abort the pre-test and vent the system using the bypass valve.
12.6 The result of the test is automatically calculated. (See
Tighten or replace any leaking fittings, if necessary, and repeat
Section 13 for the derivation of the HiReTS Peak and Total
9.6.
numbers.)
9.9 Checkthealignmentandfocusofthepyrometerandthe
straightness of the capillary tube in accordance with the
13. Calculation of Result
manufacturer’s handbook.
13.1 The HiReTSTotal number is the total ofthedifference
between the minimum and final temperatures measured at the
10. Standard Operating Conditions
required positions, along the surface of the capillary tube,
10.1 Fuel Test Temperature, preset at 290°C or as specified
during the test.
in applicable specifications or as agreed upon between the
HiReTSTotalnumber5dT 1dT 1dT 1dT 1dT 1dT 1dT
1 2 3 4 5 6 7
parties.
1dT 1dT ……1dT (1)
8 9 n
10.2 Fuel Flow Rate, preset at 35 mL/min or as specified in
applicablespecificationsorasagreeduponbetweentheparties.
where:
10.3 Number of Capillary Scans, preset as 13 (for a 65 min
dT = difference between the minimum and final tempera-
n
test) or 25 (for a 125 min test), or as specified in applicable
turesmeasuredatPosition n,°Cduringthetestwhile
specifications or as agreed upon between the parties.
the fuel exit temperature is maintained at a stable
level.
NOTE 3—Each capillary scan takes 5 min to complete.
13.2 The HiReTS Peak number is the largest of the differ-
NOTE 4—Other test temperatures, besides 290°C, and flow rates,
besides 35 mL/min, can be used but the precision may be affected. ences between the minimum and final temperatures measured
at any of the required positions, along the surface of the
11. Calibration and Standardization
capillary tube, during the test.
11.1 Ensure that all of the manufacturer’s instructions for
13.3 Express the HiReTS Total and Peak results as whole
calibrating,checking,cleaning,andoperatingtheapparatusare
numbers. Round up any fractions. Use the formats T65, T125,
followed.
P65andP125todenoteTotal(T)orPeak(P)andthetesttime.
11.2 Verify the performance of the temperature, flow, and
14. Report
pressure sensors at least every 6 months. The testing of fuels
with poor thermal stability may necessitate more frequent
14.1 Report the source, type, and identification of the
equipment verification and cleaning.
material tested, plus the date tested.
14.2 Report the result of the test (see 13.3) and the number
12. Procedure
of capillary scans. Refer to this test metho
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