ASTM D7739-11(2020)

Standard Practice for Thermal Oxidative Stability Measurement via Quartz Crystal Microbalance

SIGNIFICANCE AND USE
3.1 The tendency of a jet fuel to resist the formation of deposits at elevated temperature is indicative of its oxidative thermal stability. This practice provides a technique for the simultaneous determination of deposit formation and oxygen consumption during the thermal oxidation of jet fuels and other hydrocarbon liquids. The practice can be used to evaluate the thermal stability of fuels and to determine the efficacy of additives in inhibiting deposition or slowing oxidation, or both. A test temperature of 140 °C and run length up to 16 h has been found to be effective for the relative evaluation of fuels and fuel additives. This practice has also been employed for other hydrocarbon liquids, such as gasoline and diesel fuels, but additional safety issues may need to be addressed by the user.
SCOPE
1.1 This laboratory practice covers the quantitative determination of surface deposits produced during the thermal oxidation of gas turbine fuels by monitoring the oscillation frequency of a quartz crystal during thermal exposure. In this practice, “thermal oxidative stability” refers to the tendency of a fuel to resist surface deposit formation during heating.  
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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-Nov-2020
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.J0.03 - Combustion and Thermal Properties

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: D7739 − 11 (Reapproved 2020)
Standard Practice for
Thermal Oxidative Stability Measurement via Quartz Crystal
1
Microbalance
This standard is issued under the fixed designation D7739; 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.
1. Scope crystal frequency decreases. The shift in resonance frequency
can be quantitatively related, in real time, to surface deposit
1.1 This laboratory practice covers the quantitative determi-
2
accumulation via a variation of the Sauerbrey equation.
nation of surface deposits produced during the thermal oxida-
tion of gas turbine fuels by monitoring the oscillation fre-
3. Significance and Use
quency of a quartz crystal during thermal exposure. In this
3.1 The tendency of a jet fuel to resist the formation of
practice, “thermal oxidative stability” refers to the tendency of
deposits at elevated temperature is indicative of its oxidative
a fuel to resist surface deposit formation during heating.
thermal stability. This practice provides a technique for the
1.2 The values stated in SI units are to be regarded as the
simultaneous determination of deposit formation and oxygen
standard. The values given in parentheses are for information
consumptionduringthethermaloxidationofjetfuelsandother
only.
hydrocarbon liquids. The practice can be used to evaluate the
1.3 This standard does not purport to address all of the
thermal stability of fuels and to determine the efficacy of
safety concerns, if any, associated with its use. It is the
additivesininhibitingdepositionorslowingoxidation,orboth.
responsibility of the user of this standard to establish appro-
Atesttemperatureof140 °Candrunlengthupto16 hhasbeen
priate safety, health, and environmental practices and deter-
found to be effective for the relative evaluation of fuels and
mine the applicability of regulatory limitations prior to use.
fuel additives. This practice has also been employed for other
1.4 This international standard was developed in accor-
hydrocarbon liquids, such as gasoline and diesel fuels, but
dance with internationally recognized principles on standard-
additional safety issues may need to be addressed by the user.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4. Apparatus
mendations issued by the World Trade Organization Technical
4.1 All dimensions without tolerance limits are nominal
Barriers to Trade (TBT) Committee.
values.
4.2 Reactor—A T316, 100 mL stainless steel reactor cylin-
2. Summary of Practice
der with an internal diameter of 5.23 cm (2.06 in.) and a depth
2.1 A quartz crystal, fitted with gold electrodes, is fully
3,4
of 4.93 cm (1.94 in.). A T316 stainless steel reactor head
immersed in test fuel contained within a reactor. An oscillator
with several openings (for example, gas inlet via dip tube, gas
circuit, connected to the crystal, supplies energy to excite the
release fitted with a dial gauge or pressure transducer,
quartz crystal and monitors its resonant frequency (nominally
thermocouple, safety rupture disk, frequency signal
5 MHz) over time via a computer interface. The reactor is
connection, sleeve for oxygen concentration probe). A
equipped with a magnetic stir bar, pressure gauge/transducer,
3
0.952 cm( ⁄8 in.)holeisdrilledinthecenterofthereactorhead
oxygen sensor (not recommended for certain test conditions,
to accommodate the frequency signal connectors. This hole
see 4.11), and thermocouple to monitor and control test
3
shall have a 0.952 cm ( ⁄8 in.) clearance from any adjacent
conditions. Prior to testing, the fuel is bubbled with the test gas
opening.
for 30 min to equilibrate.After equilibration, the reactor vessel
is isolated and raised to test temperature and pressure. As
deposits accumulate on the crystal surface during the run, the
2
Klavetter, E. A., Martin, S. J., and Wessendorf, K. O., “Monitoring Jet Fuel
Thermal Stability Using a Quartz Crystal Microbalance,” Energy & Fuels, Vol 3,
1993, pp. 582-588.
1 3
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum The sole source of supply of the apparatus (Parr Instrument cylinder model
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom- #452HC8 (100 mL)) known to the committee at this time is Parr Instrument
mittee D02.J0.03 on Combustion and Thermal Properties. Company, 211 Fifty-Third St., Moline, IL 61265-1770.
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