Scanning Brookfield Technique (SBT)
(According to ASTM D5133
and D7110)
"Studies of the Flow and Gelation Response of Jet Fuels at Critical Low Temperatures"
Written by Theodore W. Selby, Savant Inc. and Marlin Vangsness & Linda Shafer,
The University of Dayton Research Institute
- Presented by Ted
Selby at the International Condition Monitoring Conference 2004 -- Joint Oil Analysis
Program (JOAP), Pensacola Beach, FL, April 18-22, 2004.
Abstract
Many jet aircraft
fly at altitudes and ambient temperatures exposing the jet fuel to
temperatures well below -40°C. Operation of aircraft at low
ambient temperatures and at higher altitudes is highly dependent on the
low-temperature flow properties of the jet fuel used. However,
these fuels vary widely in manufacture around the world and in quality
levels within a given hierarchy of fuels from commercial Jet A and Jet
A-1 to military JP-4 through JP-8 and more extended fuels.
Thus, the low-temperature viscosity and rheology of jet fuels is a
primary consideration in determining the temperature range within which
the aircraft can be operated. In particular, the tendency of the
fuel to form a congealed or gelated condition at temperatures below
-40°C can markedly restrict the operation of the aircraft both in
altitude and in flight path.
This paper shows application of the Scanning Brookfield Technique to
determine the viscosity and gelation tendencies of jet fuels over a
range of temperatures down to -65°C. Of critical
significance, the paper presents information on the practicality of
additive treatment approaches to significantly improve the operational
range of jet fuels at these very low temperatures.
"Pumpability -- Past Accomplishments; Present
and Future Challenges"
Written by Theodore W. Selby, Savant Inc.
-Published in Oil Flow Studies at Low Temperatures in Modern
Engines, ASTM STP 1388, H. Shaub, Ed., ASTM, West Conshohocken, PA
"Applying the Low-Temperature Scanning Brookfield
Technique to Analysis of Lubricants, Transmission Fluids, and Fuels"
Written by Gregory C. Miiller, Tannas Co. and Theodore W. Selby, Savant
Inc.
-
Presented by Greg Miiller at the Gulf Coast Conference, Galveston
Island, TX
Abstract
Adequate flow response can be a problem
with lubricants, transmission/differential fluids, and fuels at low
temperatures. In developing lubricants or fuel formulations expecting
to function well at low temperatures, it is critical to study their
behavior over the broadest temperature range likely to be encountered.
This can prove to be a complex task using the full scale equipment or
even with instruments requiring single point measurements.
This paper discusses a simple
scanning approach using rotational viscometry that provides a broad
temperature range yet specific evaluation of potential flow problems in
lubricants and fuels.
"Problems in Bench Test
Prediction
of Engine Oil Performance at Low Temperature"
Written by Theodore Selby, Savant Inc.
- SAE Paper #922287, SAE International Fuels and Lubricants
Meeting and Exposition in San Francisco, California, October 19-22, 1992.
Abstract
The author points out the necessity of a reevaluation of the SAE
J300 Engine Oil Viscosity Classification System and of the instruments and bench
tests developed over the last 30 years to predict low-temperature engine oil performance.
Greater ease in starting engines at low temperatures as a consequence of lower
friction, electronic timing, and fuel injection has resulted in engines with potentially
much higher Critical Starting Viscosities than those which formed the basis for
the low-temperature portion of the SAE J300 Classification System. Presenting
some of the pertinent low-temperature data available from a well-known engine
oil database, the author discusses the consequences of this situation with regard
to a number of questions related to the present application of pumpability and
startability bench tests, their limitations, and the importance of finding ways
to meet the technical challenges. In an effort to encourage dialogue, a
suggested replacement for the low-temperature section of the SAE J300 Classification
System is proposed which would alter the present system's startability-bias with
a gelation-bias reflecting both the improvement in engine startability and the
resultant increasing vulnerability of the engine to air-binding phenomena.
"The Scanning Brookfield
Technique
of Low-Temperature, Low-Shear Rheology - Its Inception, Development,
and
Applications"
Written by T.W. Selby, Savant Inc.
- Presented at the ASTM Symposium on Low-Temperature
Lubricant Rheology: Measurement and Relevance To Engine Operation,
Austin, Texas, December 10, 1991.
- Published in the ASTM STP 1143 technical book
entitled: "Low Temperature Lubricants Rheology Measurement and
Relevance to Engine Operation; pages
33-64. Robert B. Rhodes, Editor.
Abstract
The development of
the Scanning Brookfield Technique (SBT) has generated new
understandings of the rheology of automotive lubricants at low
temperatures, particularly in regard to the phenomenon of air-binding,
which is believed to be caused by oil gelation. The latter
phenomenon has been directly implicated in the pumpability failure of
engines in the field and in cold-room simulation.
The paper first traces the prior studies and use of the Brookfield
Viscometer at low temperature -- work which generated low-temperature
information on lubricants and methods ultimately leading to the
development of the Scanning Brookfield Technique (SBT) and the
application of this technique to the detection of the presence and
severity of gelation at lower temperatures of automotive
operation. The SBT has shown close correlation with the
Pumpability Reference Oils (PROs) used in the ASTM engine pumpability
study and has detected significant gelation in all known field- or
engine-failing oils.
The most recent studies generated by the SBT show that the technique
permits the measure of new criteria of gelation, two of which are: 1)
Gelation Index, a measure of maximum gelation severity closely
correlated with the yield stress of lubricant, and 2) Gelation
Temperature, the temperature at which Gelation Index is generated.
"Analysis of ASTM/IP Engine
Pumpability
Data -- Pertinent Insights Concerning a Landmark Cooperative Study"
Written by T.W. Selby
- SAE Paper #910751, SAE International
Congress
and Exposition, Detroit, Michigan, February 28, 1991.
"The Use of the Scanning
Brookfield
Technique to Study the Critical Degree of Gelation of Lubricants at Low
Temperatures"
Written by T.W. Selby
- SAE Paper #910746, SAE International Congress
and Exposition, Detroit, Michigan, February 28, 1991.
"Further Considerations of Low-Temperature,
Low-Shear Rheology Related to Engine Oil Pumpability - Information from The
Scanning Brookfield Technique"
Written by Theodore W. Selby
- SAE Paper #852115, SAE International Fuels and
Lubricants Meeting and Exposition, Tulsa, Oklahoma, October 21-24,
1985.
"Low Temperature Flow
Properties
of Engine Oils"
Written by T.W. Selby
- A written discussion of Paper No. 820509 by R.L.
Stambaugh and J.H. O'Mara of Rohm & Haas Company, SAE International
Congress, February, 22-26, 1982.
"Low Shear, Low Temperature
Properties
of Engine Oils - Techniques with the Brookfield Viscometer"
Written by T. W. Selby and D.A. Piasecki
- SAE Paper #800367, SAE/ASTM Symposium on the
Relationship
Between Engine Oil Viscosity and Engine Performance,
Paper VI, SAE Congress and Exposition,
Detroit, Michigan, February 25-29, 1980.
savant@savantgroup.com
