ASTM D7097-19

Standard Test Method for Determination of Moderately High Temperature Piston Deposits by Thermo-Oxidation Engine Oil Simulation Test—TEOST MHT

SIGNIFICANCE AND USE
5.1 The test method is designed to predict the deposit-forming tendencies of engine oil in the piston ring belt and upper piston crown area. Correlation has been shown between the TEOST MHT procedure and the TU3MH Peugeot engine test in deposit formation. Such deposits formed in the ring-belt area of a reciprocating engine piston can cause problems with engine operation and longevity. It is one of the required test methods in Specification D4485 to define API Category-Identified engine oils.6
SCOPE
1.1 This test method covers the procedure to determine the mass of deposit formed on a specially constructed test rod exposed to repetitive passage of 8.5 g of engine oil over the rod in a thin film under oxidative and catalytic conditions at 285 °C. The range of applicability of the Moderately High Temperature Thermo-Oxidation Engine Test (TEOST MHT2) test method as derived from an interlaboratory study is approximately 10 mg to 100 mg. However, experience indicates that deposit values from 1 mg to 150 mg or greater may be obtained.  
1.2 This test method uses a patented instrument, method and patented, numbered, and registered depositor rods traceable to the manufacturer3 and made specifically for the practice and precision of the test method.4  
1.3 The values stated in SI units are to be regarded as standard.  
1.3.1 Although not an SI unit, the special name liter (L) is allowed by SI for the cubic decimeter (dm3) and the milliliter (mL) for the SI cubic centimeter (cm3). Likewise, the special name millimeter (mm) is allowed by SI as a measurement of length.  
1.4 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.  
1.5 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-2019
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.09.0G - Oxidation Testing of Engine Oils

Relations

• Replaces: ASTM D7097-16a - Standard Test Method for Determination of Moderately High Temperature Piston Deposits by Thermo-Oxidation Engine Oil Simulation Test—TEOST MHT
• Effective Date: 01-Dec-2019
• Refers: ASTM D6335-19 - Standard Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
• Effective Date: 01-Dec-2019
• Refers: ASTM D4485-18 - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 01-Jul-2018
• Refers: ASTM D6335-18 - Standard Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
• Effective Date: 01-Jun-2018
• Refers: ASTM D4485-16 - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 15-Dec-2016
• Refers: ASTM D6335-16 - Standard Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
• Effective Date: 01-Oct-2016
• Refers: ASTM D4485-15a - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 15-Apr-2015
• Refers: ASTM D4485-15 - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 01-Apr-2015
• Refers: ASTM D4485-14 - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 01-Dec-2014
• Refers: ASTM D4485-11b - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 01-Oct-2011
• Refers: ASTM D4485-11a - Standard Specification for Performance of Active API Service Category Engine Oils
• Effective Date: 01-Jul-2011
• Refers: ASTM D4485-11 - Standard Specification for Performance of Engine Oils
• Effective Date: 01-May-2011
• Refers: ASTM D4485-10a - Standard Specification for Performance of Engine Oils
• Effective Date: 01-Jul-2010
• Refers: ASTM D4485-10 - Standard Specification for Performance of Engine Oils
• Effective Date: 01-May-2010
• Refers: ASTM D6335-09 - Standard Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
• Effective Date: 01-Jun-2009

Overview

ASTM D7097-19 is a standard test method developed by ASTM International for the determination of moderately high temperature piston deposits by the Thermo-Oxidation Engine Oil Simulation Test (TEOST MHT). Engine oil can form deposits at elevated temperatures, particularly in the piston ring belt and upper piston crown area of reciprocating engines. Such deposits may lead to reduced engine performance, increased maintenance, and shorter engine life. The TEOST MHT procedure provides an accelerated, laboratory-based means to predict deposit-forming tendencies, supporting the design and selection of engine oils that deliver better performance and longevity.

This test method involves circulating a small amount of engine oil over a specialized test rod under controlled oxidative and catalytic conditions at 285 °C, simulating the thermal stresses found in actual engine environments. The process measures the mass of deposits formed, aiding engine oil formulation and quality control.

Key Topics

• Purpose: Supports the evaluation of engine oil deposit-forming tendencies at moderately high temperatures, mainly in the piston ring belt area.
• Test Procedure: Involves a patented instrument and rod, dynamically exposing 8.5 g of test oil mixed with catalyst over a heated wire-wound rod for 24 hours at 285 °C.
• Measurement Range: Typically, the deposit mass measured ranges from 10 mg to 100 mg (with practical experience extending from 1 mg to 150 mg or greater).
• Precision and Traceability: Utilizes patented, manufacturer-traceable depositor rods for high precision and repeatability.
• Correlation: The TEOST MHT procedure has shown correlation with the TU3MH Peugeot engine test for deposit formation, adding credence to its predictive value.
• Standardization: One of the required methods in ASTM D4485 for defining API Category-Identified engine oils.

Applications

The ASTM D7097-19 test method is used primarily by oil formulators, engine manufacturers, and quality assurance laboratories to:

• Assess Engine Oil Performance: Evaluate new and existing formulations for deposit control under high-temperature oxidative conditions.
• Support Engine Oil Specifications: Satisfy performance testing requirements for API classified engine oils, as referenced in ASTM D4485.
• Predict Field Performance: Anticipate deposit-related problems such as stuck piston rings, increased blow-by, or oil consumption in actual engines.
• Benchmark Oils: Compare the deposit-forming tendencies of different lubricants under standardized laboratory conditions.
• Assist Regulatory and Compliance Testing: Meet industry and international standards for engine oil performance.

Related Standards

• ASTM D4485: Specification for Performance of Active API Service Category Engine Oils, where TEOST MHT is a required test.
• ASTM D6335: Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test (TEOST 33C), focused on higher temperature conditions such as those in turbochargers.
• API Engine Oil Categories: Defines service classifications and minimum deposit control requirements, often referencing ASTM D7097.

Practical Value

Using the TEOST MHT test method outlined in ASTM D7097-19 allows industry professionals to proactively control engine oil quality, optimize formulations for deposit resistance, and ensure compliance with market and regulatory expectations. By simulating real-world engine conditions, this method delivers predictive insights that can reduce costly engine failures and extend both oil and engine life.

Keywords

ASTM D7097-19, TEOST MHT, engine oil oxidation, piston deposit test, engine oil simulation, piston ring belt deposits, engine oil performance, ASTM engine oil test, API engine oil category, lubricant deposit control, oil quality assessment.

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: D7097 − 19
Standard Test Method for
Determination of Moderately High Temperature Piston
Deposits by Thermo-Oxidation Engine Oil Simulation Test—
TEOST MHT
This standard is issued under the fixed designation D7097; 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* responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This test method covers the procedure to determine the
mine the applicability of regulatory limitations prior to use.
mass of deposit formed on a specially constructed test rod
1.5 This international standard was developed in accor-
exposedtorepetitivepassageof8.5gofengineoilovertherod
dance with internationally recognized principles on standard-
in a thin film under oxidative and catalytic conditions at
ization established in the Decision on Principles for the
285°C. The range of applicability of the Moderately High
2 Development of International Standards, Guides and Recom-
Temperature Thermo-Oxidation Engine Test (TEOST MHT )
mendations issued by the World Trade Organization Technical
test method as derived from an interlaboratory study is
Barriers to Trade (TBT) Committee.
approximately 10mg to 100mg. However, experience indi-
cates that deposit values from 1mg to 150mg or greater may
2. Referenced Documents
be obtained.
2.1 ASTM Standards:
1.2 Thistestmethodusesapatentedinstrument,methodand
D4485Specification for Performance ofActiveAPI Service
patented, numbered, and registered depositor rods traceable to
Category Engine Oils
the manufacturer and made specifically for the practice and
D6335Test Method for Determination of High Temperature
precision of the test method.
Deposits by Thermo-Oxidation Engine Oil Simulation
1.3 The values stated in SI units are to be regarded as
Test
standard.
1.3.1 Although not an SI unit, the special name liter (L) is
3. Terminology
allowed by SI for the cubic decimeter (dm ) and the milliliter
3.1 Definitions of Terms Specific to This Standard:
(mL) for the SI cubic centimeter (cm ). Likewise, the special
3.1.1 bubble airflow gauge, n—a precision bore glass tube
name millimeter (mm) is allowed by SI as a measurement of
marked in tenths of a milliliter used to measure accurately the
length.
flow rate of air around and past the depositor rod and to
1.4 This standard does not purport to address all of the
calibrate mass air flow controllers recommended for use in the
safety concerns, if any, associated with its use. It is the
procedure.
3.1.2 depositor rod deposits, n—particulate matter formed
on the depositor rod surface by oxidation of the thin film of
This test method is under the jurisdiction of ASTM Committee D02 on
passingoilexposedtotherodtemperatureandair,andweighed
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.09.0G on Oxidation Testing of Engine Oils. after appropriate washing and drying to obtain the net mass
Current edition approved Dec. 1, 2019. Published January 2020. Originally
gain.
approved in 2005. Last previous edition approved in 2016 as D7097–16a. DOI:
3.1.3 filter deposits, n—particulates washed from the de-
10.1520/D7097-19.
TEOSTand MHTare registered trademarks of theTannas Co. (Reg. 2001396),
positor rod after the test and collected on a special multi-layer
Tannas Company, 4800 James Savage Rd., Midland, MI 48642.
filter cartridge.
The sole source of supply of the apparatus known to the committee at this time
is Tannas Company, 4800 James Savage Rd., Midland, MI 48642. If you are aware 3.1.4 TEOST , n—an acronym for Thermo-Oxidation En-
of alternative suppliers, please provide this information to ASTM International
gine Oil Simulation Test.
Headquarters.Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend.
The TEOST instrument, method and rod are patented. Interested parties are
invited to submit information regarding the identification of an alternative(s) to this For referenced ASTM standards, visit the ASTM website, www.astm.org, or
patented technology to ASTM Headquarters. Your comments will receive careful contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
consideration at a meeting of the responsible technical committee, which you may Standards volume information, refer to the standard’s Document Summary page on
attend. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7097 − 19
3.1.5 total rod deposits, n—the mass of deposits collected 6.1.1.2 Depositor Rod, Wire-Wound, a specially patented,
onthedepositorrodplusanymassofdepositswashedfromthe numbered, and registered steel tube wound with pretreated
depositor rod and later extracted on a filter. steel wire. The steel tube is formed to a selected interior
diameter to precisely contact the surface of a metal-sheathed
3.1.6 volatilized oil, n—oil vapor coalesced on the mantle
thermocouple.Theregistereddepositorrodsarerequiredtorun
wall, and subsequently collected in a vial.
the TEOST MHT procedure. (See Fig. 4, Fig. 5, and Fig. 7.)
3.2 Abbreviations:
NOTE 1—Precision of the TEOST MHT procedure is highly dependent
3.2.1 MHT , n—moderately high temperature.
on the uniformity of manufacture and use of patented and registered
3.2.1.1 Discussion—The TEOST MHT procedure evaluates
depositor rods. Each depositor rod is numbered and traceable to the
deposit formation at temperatures that are closely related to
manufacturer and raw steel tubing mill.
those of the piston ring zone in reciprocating engines (as
6.1.1.3 End-cap, Upper, holds the upper end of the glass
distinguished from the much higher temperatures associated
mantleanddepositorrodinplaceandallowsairandoiltoenter
with the TEOST 33C, Test Method D6335, procedure for
the deposit-forming zone separately. (See Fig. 4 and Fig. 7.)
determining potential deposits in turbochargers).
6.1.1.4 End-cap, Lower, holds the lower end of the glass
4. Summary of Test Method mantleanddepositorrodinplaceandprovidesanoutletforthe
oil to pass into the sample flask and subsequently to the
4.1 Deposit-forming tendencies of an engine oil under
recirculating pump inlet tubing. (See Fig. 6.)
oxidative conditions are determined by circulating an oil-
6.1.1.5 End-cap Nuts, Four, used for compressing small
catalyst mixture comprising a small sample (8.4g) of the oil
O-rings around depositor rod and for positioning and sealing
andaverysmall(0.1g)amountofanorgano-metalliccatalyst.
theoilfeedtubeandsealingtheairinlettubing.(SeeFig.4and
This sample mixture is then circulated for exactly 24h in the
Fig. 5.)
TEOST MHT instrument over a special wire-wound depositor
6.1.1.6 Glass Mantle, the glass casing that surrounds the
rod heated by electrical current to a controlled temperature of
depositor rod and diverts volatilized oil into a collecting vial.
285°C at the hottest location on the rod. The depositor rod is
(See Figs. 4-6.)
weighed before and after the test and any deposit formation on
6.1.1.7 Mantis Clip, a wire-spring device holding the
therodaswellasanydepositscollectedfromrodwashingsare
sampleflaskinplaceonthelowerend-cap.(SeeFig.2andFig.
determined. During the test, precisely controlled and directed
6.)
air is caused to bathe the oil flowing down the depositor rod
and, thereby, to provide opportunity for oxidation. Precision of 6.1.1.8 Lower End-cap Seal, a flexible oil temperature
thetestisstronglyinfluencedbythecareinmanufactureofthe resistant rubber seal (see Fig. 9).
wire-wound steel depositor rods and the treatment of the
6.1.1.9 Oil Feed Tube, the avenue for oil to be delivered
coating of the wound wire, the rate of air flow, and the amount
from the pump to the top of the depositor rod.
and degree of mixing of the catalyst.
6.1.1.10 End cap O-rings, Large, Petroleum-resistant, cre-
ate a seal between the end-caps and glass mantle. (See Fig. 5.)
5. Significance and Use
6.1.1.11 End cap O-rings, Small, Petroleum- and Heat-
5.1 The test method is designed to predict the deposit- resistant, creates an air and fluid seal between depositor rod
forming tendencies of engine oil in the piston ring belt and
and end-caps. (See Fig. 5.)
upper piston crown area. Correlation has been shown between
6.1.1.12 Pump Outlet Tubing, a flexible transparent vinyl
the TEOST MHT procedure and the TU3MH Peugeot engine
tube of 3.2mm outer diameter with a flared end used to
test in deposit formation. Such deposits formed in the ring-belt
transport the oil sample from the oil pump to the oil feed tube.
area of a reciprocating engine piston can cause problems with
(See Fig. 6.)
engine operation and longevity. It is one of the required test
6.1.1.13 Sample Flask, a small (~25mL), modified form of
methods in Specification D4485 to define API Category-
an Erlenmeyer flask with sidearm into which the catalyst and
Identified engine oils.
sample are first weighed, then later used to feed the sample to
the circulating system. (See Fig. 2 and Fig. 6.)
6. Apparatus
6.1.1.14 Stainless Steel Hex Screws and Busbar End Piece,
6.1 TEOST MHT Instrument, with specific fittings for the
these secure the depositor rod to the busbars.
MHTprocedure including parts and assemblies are as follows:
6.1.1.15 Thermocouples, Two, stainless steel sheathed,
6.1.1 Depositor Rod Casing Assembly:
1.57mmdiameterby150mmlength.One,aJ-type,isusedfor
6.1.1.1 Ceramic Isolators, special non-conductive fittings
controllingthetesttemperature(depositorrod)whiletheother,
that compress the depositor rod O-rings into the end-caps and
a K-type, is used to protect against an over-temperature
centers the depositor rod in the end-caps to prevent leakage of
condition.
oil from the lower end-cap. (See Figs. 4 and 5.)
6.1.1.16 Thermocouple Locking Collar, a fitting that can be
tightened on the thermocouple to ensure the thermocouple tip
is at the correct position when placed inside the depositor rod.
Selby,T.W.,andFlorkowski,D.F.,“TheDevelopmentoftheTEOSTProtocol
(See Fig. 4.)
MHT Bench Test of Engine Oil Piston Deposit Tendency,” Supplement to the
6.1.1.17 Volatiles Vial Clip, the device that holds the vola-
Proceedings of the 12th Esslingen Colloquium,Esslingen,Germany,January11-13,
2000, pp. 55-62. tiles collection vial in place on the mantle. (See Fig. 4.)
D7097 − 19
FIG. 1 Bubble Gauge
6.1.2 Airflow Control Assembly, sets air flow at chosen flow 6.1.2.2 Calibrated Flow Meter, capable of measuring ap-
rate.
proximately 1mL⁄min to 20mL⁄min of air and providing a
6.1.2.1 Bubble Airflow Gauge, a device for precisely estab-
continuous reading on airflow rate when calibrated.
lishing the airflow rate and calibrating the flow meter from
1mL⁄min to 30mL⁄min. (See Fig. 1.)
D7097 − 19
6.2.7 Vials and Caps, a vial and matching cap of 10mL or
more in volume with an 11.5mm diameter mouth and an outer
diameter of 20mm to collect the volatile material emitted by
the oil and collected on the mantle wall during the test as well
as the recovered, end-of-test oil sample. (See Fig. 4.)
6.2.8 Weighing Boat, a light, circular or oblong weighing
container, preferably made of aluminum with a diameter or
length of 7cm to 10cm and notched in two diametrically
opposed places to prevent the rod from rolling (see Fig. 3)or
FIG. 2 Sample Flask with Stirring Bar and Mantis Clip
a suitable weighing device capable of preventing the rod from
rolling and from losing any deposits.
6.1.2.3 Handheld Digital Flow Meter, an optional device to
monitor air flow to or out of the mantle, capable of reading a
6.2.9 Air-Flow Restrictor—a small PTFE washer designed
flow rate of 10.0mL⁄min 6 0.1mL⁄min of air.
to limit the amount of air allowed to pass between the sample
6.1.2.4 Precision Digital Mass Flow Controller, an optional
flask and the drain on the lower end-cap.
devicethatallowstheprecisecontroloftheinputairflow.(See
Fig. 1a.)
7. Reagents and Materials
6.1.2.5 Stopwatch, reading to 1/100s.
7.1 Abrasive Paper, 800-grit emery (aluminum oxide).
6.1.3 Filtering Flask Assembly, provides the means for
filtering particles washed from the depositor rod. (See Fig. 8.)
7.2 Acetone, particle-free, reagent grade, for final cleaning
6.1.3.1 Filter Cartridge, a special multilayer filter made for
of new depositor rods. (Warning—Flammable. Health haz-
the TEOST MHT procedure fitting the end of the filter funnel
ard.)
also made for the TEOST procedure. (See Fig. 8.)
7.3 Air, oil-free, clean, and dry, obtained from cylinder gas
6.1.3.2 Filter Funnel, a special combination funnel of
or house line, regulated to 15kPa to 100kPa (2psi to 15psi)
~400mL capacity, necking down to a 10mL graduated or
at more than 690kPa (100psi).
non-graduatedsectionthat,inturn,endsinaglassorLuer-lock
tipfittingthespecialfiltercartridgeusedintheprocedure.(See
7.4 Cyclohexane or Other Alkane Hydrocarbon Solvent,
Fig. 8.)
reagent grade. (Warning—Flammable.) Cyclohexane is the
6.1.3.3 Filter Tube Assembly, a metal or polyethylene tube
onlyallowednaphthenichydrocarbon.Donotuseanyaromatic
inserted through a No. 8 rubber stopper in the vacuum flask to
hydrocarbons. Throughout the further description of the test,
fit the lower outlet of the filter cartridge. (See Fig. 8.)
the solvent selected is referred to as “hydrocarbon solvent.”
6.1.3.4 Vacuum Flask, 1000mL capacity for collecting the
7.4.1 The volatility of the cyclohexane as the solvent
hydrocarbon solvent and oil during the filter rinse.
ensurestimelyevaporationofthedepositsontherodandfilter.
6.1.3.5 Vacuum Source, a vacuum source sufficient to draw
If another alkane hydrocarbon is used as the solvent, longer
the hydrocarbon solvent and oil through the filter and provide
drying times may be required. The higher the purity of the
the necessary filter drying.
solvent, the quicker the solvent should evaporate.
6.1.3.6 Wire Rod, a thin, clean, stainless steel wire rod, for
dislodging any deposits trapped in the narrow portion of the
7.5 Catalyst —Catalyst contains iron, lead, and tin in ratios
filter funnel just above the filter.
chosen for emulating engine deposit conditions.
6.2 Ancillary Equipment, needed or helpful:
7.5.1 Forlongtermstorage,itisacceptabletorefrigeratethe
6.2.1 Balance, capable of weighing deposits to the nearest
catalystuntilafewhoursbeforeuse(letcatalystwarmtoroom
0.1mg with a minimum capacity of 100g.
temperature before opening to eliminate condensation). Tem-
6.2.2 Catalyst Syringe,a small glass syringe that uses either
porary unopened storage, up to four weeks, may be at room
a glass or PTFE plunger (do not use rubber plunger) of 100µL
temperature.
capacity,forcarefullymeteringthecatalystbeingweighedinto
7.6 Certified Reference Oils, certified low deposit fluid
the sample flask. (An optional approach is to use a small
(LDF, about 10mg to 15mg), medium deposit fluid (MDF,
disposable glass pipet.)
about 40mg to 50mg), and high deposit fluid (HDF, about
6.2.3 Oil Sample Transfer Pipettes, disposable glass or
70mg to 90mg).
plastic pipettes or droppers.
6.2.4 Oil Extraction Test Tubes, three glass test tubes of
7.7 Combination Pump Calibration and Temperature Con-
sufficientheighttocoverallbuttheupper20mmofaninserted 3
trol Thermocouple Depth Setting Oil, TPC-1, ahighlydeposit-
deposit-carrying rod. Plastic tubes are not acceptable.
resistant oil used in setting pump calibration and temperature
6.2.5 Temperature Recorder, an optional device for tracking
control calibration without forming significant deposits on the
the temperature of the upper depositor rod thermocouple over
depositor rod during these calibrations.
the 24h period of the test.
7.8 Varnish Cleaning Liquid, used in cleaning varnish from
6.2.6 Thermocouple Depth Insertion Gauge, an optional
measurementdevicefabricatedforsimplesettingandchecking mantle,end-caps,andothercomponentsoftheequipmentafter
test. Other glass cleaners with varnish removing capabilities
of the thermocouple insertion depth, using a millimeter gradu-
ation scale. also may be used.
D7097 − 19
FIG. 3 Weighing Boat and Rod
FIG. 4 Depositor Assembly (Cut-away View)
8. Programming the Apparatus set them to the specified settings for a specific controller. See
the individual unit Instrument Manual for more details on the
8.1 PID (proportional, integral, and derivative) Settings for
specific settings and on the adjustment technique.
Temperature Control—In order for the thermocouple sensitiv-
ity and response values (PID settings) to have the minimum
excursion from the temperature value desired during operation
D7097 − 19
FIG. 5 Insertion of Oil Inlet Tube (Cut-away View)
8.2 Temperature Controller Setting—Set the temperature 9.1.2 Calibration of Air Flow Rate Using an Air Flow
control program to maintain 285°C for 24h according to the Meter:
instructions in the Instrument Manual.
9.1.2.1 Use the bubble gauge or other primary calibration
device semi-annually to check or calibrate analog or digital
8.3 If using a strip chart recorder, turn on the strip chart, set
flow meters (see Note 3).
thechartspeedto10mm⁄h,butdonotlowerthepen(s)orturn
9.1.2.2 Set up the bubble gauge and flow meter equipped
on the chart drive at this time.
withafineneedlevalveasshownschematicallyinFig.1awith
8.4 If using other means of continuously recording
a three-way stopcock or Fig. 1c with a ball valve.
temperatures, prepare these for receiving information.
NOTE 3—A handheld flow meter may also be used.
9. Calibration and Standardization
9.1.2.3 Connect the dry air source to the flow meter and set
9.1 Calibration of Air Flow Rate (alternative procedures, the source’s regulator to a pressure value no greater than
follow 9.1.1 and 9.1.2): allowed by the tolerances of the flow meter used.
9.1.1 Calibration of Air Flow Rate Using a Mass Flow
9.1.2.4 Inserttheendoftheairinlettubeintothesoftrubber
Controller:
tubing attached to the bubble gauge and check that the joint is
9.1.1.1 Use the bubble gauge or other primary calibration
leak tight with soap solution.
device semi-annually to check or calibrate a mass flow
9.1.2.5 Adjusttheflowmeterrateandretestbubbleriserate
controller.
to bring the flow rate to 10.0mL⁄min 6 0.2mL⁄min.
(1)The TEOST MHT protocol is sensitive to flow rate,
9.2 OilPumpRateCalibration—Followthetechniqueinthe
therefore primary calibration of mass flow meters or other
manufacturer’s Instrument Manual to set a test oil flow rate of
forms of air flow control such as analog or digital flow meters
0.25g⁄min 6 0.01g⁄min.
is desired to ensure proper flow rate.
9.3 Temperature Controller Setting—Follow the technique
NOTE 2—Models of some mass flow meters may permit adjustment of
in the manufacturer’s Instrument Manual to set a test tempera-
the readout to the calibration value when the appropriate air flow is
reached. ture of 285°C on the temperature controller.
D7097 − 19
FIG. 6 Flexible Tube Connection to Oil Feed Tube and Sample
Flask Placement with Mantis Clip (Cut-away View)
FIG. 7 Front and Side Views of Upper Mantle End Cap Showing Air Inlet
9.4 Calibration of Control Thermocouple: usingafineabrasivepad(500gritorfiner)oremerypaper(800
9.4.1 Calibrate the depositor rod temperature control ther-
grit). The resulting cleaned surface shall show bright metal,
mocouple in a liquid or sand bath maintained at 285°C 6
particularly in the temperature-sensitive area at the end of the
50°C and, if necessary, adjust the temperature offset of the
thermocouple. Do not overclean the thermocouple surface or
temperature controller to match the bath temperature for this
use coarse abrasives, as the thermocouple wall could be
thermocouple. In the absence of either a liquid, block or sand
thinned and damaged.
bath,boilingdistilledwatermaybeusedtocalibrateat100°C.
9.5 Determination, Setting, and Use ofAppropriate Position
The temperature should be able to be calibrated within
for the Temperature Control Thermocouple—Follow the tech-
60.1°C.
nique in the manufacturer’s Instrument Manual to find the
9.4.2 Before each reuse of the thermocouple, clean any
hottest point within the bore of the depositor rod.
corrosion or other deposits from the thermocouple surface
D7097 − 19
10. Instrument and Sample Preparation
10.1 Beforetestingunknownsamples,confirmthefunction-
ality of the TEOST MHT instrument by testing one of the
certified reference oils (see 7.6). Choosing one of the certified
referenceoilsmentionedin7.6,followthedirectionsinSection
10.
10.2 Make sure that the TEOST heat switch is in the off
position to prevent any accidental startup of the test.Then turn
on the main power switch and allow 30min or more for the
instrument electronics to warm up. Ensure that the pump
switch is off.
10.3 Makesurethatthethermocouplesareclean(see9.4.2).
10.4 Invert both the catalyst vial and the oil container at
least three times to ensure homogeneity of both components
prior to use.
10.5 Place a clean sample flask (see Fig. 2) on a precision
balanceandtarethebalance(tobringtheindicatedmassofthe
container to zero).
10.6 Using a microliter glass syringe that uses either a glass
or PTFE plunger (do not use rubber plunger), or optional
disposable glass pipet, add the pre-calculated mass of catalyst
requiredtomake8.5gofsample-catalystmixturebasedonthe
certifiedvalueofthecatalystandrecordthemasstothenearest
0.0001g. The range for the mass of catalyst to be added shall
be 60.0003g of the mass required.
NOTE 6—The mass of oil required for the appropriate mixture of
catalyst-to-oil ratio is stated on the label of the vial of certified catalyst.
10.7 Again,tarethebalanceandaddtherequiredmassofoil
to the sample flask to make the sample-catalyst mixture total
8.5g 6 0.05g. The range for the mass of the oil to be added
shall be 60.01g of the mass required to obtain the catalyst/oil
ratio shown on the catalyst bottle. If more oil than required is
added, make a new sample.
NOTE 7—An electronic file containing a generic calculation table to
FIG. 8 Filter Funnel Setup
determine the appropriate catalyst/sample weights can be obtained from
the ASTM Test Monitoring Center.
10.8 Add a TFE-fluorocarbon-coated magnetic stirring bar
to the sample flask, and place the flask on the magnetic stirrer
incorporated on the platform of the TEOST (or other appro-
9.5.1 Insert the thermocouple gently (see Note 5) into the
bore of the depositor rod to bring the collar into contact with priate magnetic stirrer) and stir for 30min to 60min. Do not
heat the mixture. Do not stir the mixture too vigorously, and
the emergent top of the rod when it is in position within the
depositor rod casing assembly positioned in the busbars. particularly avoid creating a large vortex where the mixture
may splash out. Be sure to load the sample and start the test
NOTE 4—The locking collar may slip if the thermocouple is forced into
within 20min of the completion of the mixing process.
the depositor rod thus resulting in a wrong position for the temperature
NOTE 8—For planning purposes, the hardware setup and the finish of
sensing area of the thermocouple.
sample mixing can be arranged to coincide, so the test can be started in a
9.5.2 If desired, adjust the strip chart recorder or other
shorter preparation time.
temperature-recording device to record temperature sensed by
11. Hardware Setup
the temperature control thermocouple.
NOTE 5—Continuously record the temperature of the controlling
11.1 Install new end-cap O-rings in both end-caps.
thermocouple at maximum sensitivity setting to determine any aberration
NOTE 9—At this point, any interest of the operator in determining the
in temperature during a run that may be caused by temporary electrical
mass of volatiles, recovered end-of-test oil, and mantle deposits will
failure or brownout of the local power supply.
require weighing and recording the initial mass of the volatiles collection
vial, the recovered oil vial, and the cleaned and dried mantle.
9.6 Install the over-temperature thermocouple according to
the manufacturer’s Instrument Manual.
9.7 Standardize the TEOST MHT procedure using certified
ASTM Test Monitoring Center, 6555 Penn Ave., Pittsburgh, PA 15206.
reference oils in accordance with Sections 10 and 15. www.astmtmc.cmu.edu.
D7097 − 19
FIG. 9 Lower End-cap Seal
slide up and down on the machined narrower section of the rod around
11.2 Using a gentle twisting motion, insert the upper end of
which the wire coil is wrapped without being too loose.
the glass mantle squarely into the upper end-cap. Avoid
11.3.4 Use hydrocarbon solvent, to rinse both the outside
chipping the mantle glass, and make sure that the hole or
and inside of the rod. Use thin, solvent-resistant laboratory
window (see Fig. 5) in the upper mantle faces the correspond-
glovesorfingercotswhenhandlingtherodtokeepnaturalskin
ing oil feed tube opening in the upper end-cap. Set this
oils from affecting the mass of the rod.
assembly aside in a safe place until required to complete the
depositor rod casing assembly.
NOTE 12—If the cots or gloves are chemically attacked by the
hydrocarbon solvent, a film or residue will be left on the surface of the
11.3 Cleaning and Weighing a Depositor Rod; Use of
gloves.
Weighing Boat:
11.3.5 Using a pipe cleaner soaked in acetone, swab the
11.3.1 Select a weighing boat (see Fig. 3) for the depositor
inside bore of the depositor rod by pushing the pipe-cleaner all
rod and obtain the boat’s mass to 60.0001g. Keep covered
the way through the bore in one direction, then repeat the
when not in use to avoid contamination from particles falling
cleaningoftheinsideboreintheoppositedirectionwithafresh
from the air.
pipe cleaner soaked in acetone. Exercise particular care in
NOTE 10—If fluctuations are seen on the balance, momentarily touch
handling and cleaning the depositor rod during this stage,
the boat to a grounding pad to eliminate static.
avoiding any distortion of the wire coil.
11.3.2 Oncethedepositorrodpreparationhasbegun,handle
11.3.6 Rinsetheoutsideandtheinsideboreofthedepositor
the rod with care and do not set the rod down except on the
rod with acetone using appropriate solvent-resistant gloves.
weighing boat. Keep covered when not in use.
11.3.7 Vacuum-dry or blow clean, dry air on the inside of
11.3.3 When handling and cleaning the wire-wound deposi-
thedepositorrodwhileholdingitbetweenthethumbandindex
torrod,becarefulnottodistortthelengthandpitchofthewire
fingers.Drytheoutsideoftherodonlybyexposuretoambient
coils.
air.
11.3.8 Set the depositor rod down in the pre-weighed
NOTE 11—The wire coils on the depositor rod are preset to a specified
pitch by the manufacturer and are adjusted to a tension to just be able to weighingboatfrom11.3.1(seeFig.3).Weighthedepositorrod
D7097 − 19
and boat to a constant mass within 60.0001 g. Record this 11.5.4 Before every test, check to ensure that the tempera-
value as the initial depositor rod and boat mass. Subtract the ture control thermocouple’s lock collar is tight and correctly
boat mass from the total mass for later determination of the positioned for the proper insertion depth. This depth was
depositor rod mass carrying deposits from the test. previously established in 9.5.
11.3.9 After the boat and depositor rod masses have been
11.5.5 Placethetemperaturecontrolthermocoupledownthe
obtained, put the covered boat aside for later use when the
top center bore of the depositor rod to the lock collar. During
depositor rod has completed its exposure to deposits for 24h.
insertion of the thermocouple in either the depositor rod or
thermocouple depth gauge, be careful not to bend the thermo-
11.4 Completing the Depositor Rod Casing Assembly (see
couple.
Figs. 4-6):
11.4.1 Pick up the pre-assembled mantle and upper end-cap
11.6 Connecting the Rigid Oil Feed Tube and the Flexible
(see 11.2) and carefully slide the depositor rod up through the
Oil Flow Tubing:
bottom of the glass mantle/upper-end-cap assembly until the
11.6.1 Connecting a New Oil Feed Tube (see Fig. 5) for
end of the depositor rod emerges through the threaded stem of
First-time Use:
the upper end-cap.
11.6.1.1 Ensure that the depositor rod casing assembly h
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7097 − 16a D7097 − 19
Standard Test Method for
Determination of Moderately High Temperature Piston
Deposits by Thermo-Oxidation Engine Oil Simulation Test—
TEOST MHT
This standard is issued under the fixed designation D7097; 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*
1.1 This test method covers the procedure to determine the mass of deposit formed on a specially constructed test rod exposed
to repetitive passage of 8.5 g of engine oil over the rod in a thin film under oxidative and catalytic conditions at 285 °C. The range
of applicability of the Moderately High Temperature Thermo-Oxidation Engine Test (TEOST MHT ) test method as derived from
an interlaboratory study is approximately 10 mg to 100 mg. However, experience indicates that deposit values from 1 mg to
150 mg or greater may be obtained.
1.2 This test method uses a patented instrument, method and patented, numbered, and registered depositor rods traceable to the
3 4
manufacturer and made specifically for the practice and precision of the test method.
1.3 The values stated in SI units are to be regarded as standard.
1.3.1 Although not an SI unit, the special name liter (L) is allowed by SI for the cubic decimeter (dm ) and the milliliter (mL)
for the SI cubic centimeter (cm ). Likewise, the special name millimeter (mm) is allowed by SI as a measurement of length.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D4485 Specification for Performance of Active API Service Category Engine Oils
D6335 Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 bubble airflow gauge, n—a precision bore glass tube marked in tenths of a milliliter used to measure accurately the flow
rate of air around and past the depositor rod and to calibrate mass air flow controllers recommended for use in the procedure.
3.1.2 depositor rod deposits, n—particulate matter formed on the depositor rod surface by oxidation of the thin film of passing
oil exposed to the rod temperature and air, and weighed after appropriate washing and drying to obtain the net mass gain.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.09.0G on Oxidation Testing of Engine Oils.
Current edition approved Sept. 1, 2016Dec. 1, 2019. Published September 2016January 2020. Originally approved in 2005. Last previous edition approved in 2016 as
D7097 – 16.D7097 – 16a. DOI: 10.1520/D7097-16A.10.1520/D7097-19.
TEOST and MHT are registered trademarks of the Tannas Co. (Reg. 2001396), Tannas Company, 4800 James Savage Rd., Midland, MI 48642.
The sole source of supply of the apparatus known to the committee at this time is Tannas Company, 4800 James Savage Rd., Midland, MI 48642. If you are aware of
alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible
technical committee, which you may attend.
The TEOST instrument, method and rod are patented. Interested parties are invited to submit information regarding the identification of an alternative(s) to this patented
technology to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7097 − 19
3.1.3 filter deposits, n—particulates washed from the depositor rod after the test and collected on a special multi-layer filter
cartridge.
3.1.4 TEOST , n—an acronym for Thermo-Oxidation Engine Oil Simulation Test.
3.1.5 total rod deposits, n—the mass of deposits collected on the depositor rod plus any mass of deposits washed from the
depositor rod and later extracted on a filter.
3.1.6 volatilized oil, n—oil vapor coalesced on the mantle wall, and subsequently collected in a vial.
3.2 Abbreviations:
3.2.1 MHT , n—moderately high temperature.
3.2.1.1 Discussion—
The TEOST MHT procedure evaluates deposit formation at temperatures that are closely related to those of the piston ring zone
in reciprocating engines (as distinguished from the much higher temperatures associated with the TEOST 33C, Test Method
D6335, procedure for determining potential deposits in turbochargers).
4. Summary of Test Method
4.1 Deposit-forming tendencies of an engine oil under oxidative conditions are determined by circulating an oil-catalyst mixture
comprising a small sample (8.4 g) of the oil and a very small (0.1 g) amount of an organo-metallic catalyst. This sample mixture
is then circulated for exactly 24 h in the TEOST MHT instrument over a special wire-wound depositor rod heated by electrical
current to a controlled temperature of 285 °C at the hottest location on the rod. The depositor rod is weighed before and after the
test and any deposit formation on the rod as well as any deposits collected from rod washings are determined. During the test,
precisely controlled and directed air is caused to bathe the oil flowing down the depositor rod and, thereby, to provide opportunity
for oxidation. Precision of the test is strongly influenced by the care in manufacture of the wire-wound steel depositor rods and
the treatment of the coating of the wound wire, the rate of air flow, and the amount and degree of mixing of the catalyst.
5. Significance and Use
5.1 The test method is designed to predict the deposit-forming tendencies of engine oil in the piston ring belt and upper piston
crown area. Correlation has been shown between the TEOST MHT procedure and the TU3MH Peugeot engine test in deposit
formation. Such deposits formed in the ring-belt area of a reciprocating engine piston can cause problems with engine operation
and longevity. It is one of the required test methods in Specification D4485 to define API Category-Identified engine oils.
6. Apparatus
6.1 TEOST MHT Instrument, with specific fittings for the MHT procedure including parts and assemblies are as follows:
6.1.1 Depositor Rod Casing Assembly:
6.1.1.1 Ceramic Isolators, special non-conductive fittings that compress the depositor rod O-rings into the end-caps and centers
the depositor rod in the end-caps to prevent leakage of oil from the lower end-cap. (See Figs. 4 and 5.)
6.1.1.2 Depositor Rod, Wire-Wound, a specially patented, numbered, and registered steel tube wound with pretreated steel wire.
The steel tube is formed to a selected interior diameter to precisely contact the surface of a metal-sheathed thermocouple. The
registered depositor rods are required to run the TEOST MHT procedure. (See Fig. 4, Fig. 5, and Fig. 7.)
NOTE 1—Precision of the TEOST MHT procedure is highly dependent on the uniformity of manufacture and use of patented and registered depositor
rods. Each depositor rod is numbered and traceable to the manufacturer and raw steel tubing mill.
6.1.1.3 End-cap, Upper, holds the upper end of the glass mantle and depositor rod in place and allows air and oil to enter the
deposit-forming zone separately. (See Fig. 4 and Fig. 7.)
6.1.1.4 End-cap, Lower, holds the lower end of the glass mantle and depositor rod in place and provides an outlet for the oil
to pass into the sample flask and subsequently to the recirculating pump inlet tubing. (See Fig. 6.)
6.1.1.5 End-cap Nuts, Four, used for compressing small O-rings around depositor rod and for positioning and sealing the oil
feed tube and sealing the air inlet tubing. (See Fig. 4 and Fig. 5.)
6.1.1.6 Glass Mantle, the glass casing that surrounds the depositor rod and diverts volatilized oil into a collecting vial. (See Figs.
4-6.)
6.1.1.7 Mantis Clip, a wire-spring device holding the sample flask in place on the lower end-cap. (See Fig. 2 and Fig. 6.)
6.1.1.8 Lower End-cap Seal, a flexible oil temperature resistant rubber seal (see Fig. 9).
6.1.1.9 Oil Feed Tube, the avenue for oil to be delivered from the pump to the top of the depositor rod.
6.1.1.10 End cap O-rings, Large, Petroleum-resistant, create a seal between the end-caps and glass mantle. (See Fig. 5.)
Selby, T. W., and Florkowski, D. F., “The Development of the TEOST Protocol MHT Bench Test of Engine Oil Piston Deposit Tendency,” Supplement to the Proceedings
of the 12th Esslingen Colloquium, Esslingen, Germany, January 11-13, 2000, pp. 55-62.
D7097 − 19
FIG. 1 Bubble Gauge
6.1.1.11 End cap O-rings, Small, Petroleum- and Heat-resistant, creates an air and fluid seal between depositor rod and
end-caps. (See Fig. 5.)
6.1.1.12 Pump Outlet Tubing, a flexible transparent vinyl tube of 3.2 mm outer diameter with a flared end used to transport the
oil sample from the oil pump to the oil feed tube. (See Fig. 6.)
6.1.1.13 Sample Flask, a small (~25 mL), modified form of an Erlenmeyer flask with sidearm into which the catalyst and sample
are first weighed, then later used to feed the sample to the circulating system. (See Fig. 2 and Fig. 6.)
6.1.1.14 Stainless Steel Hex Screws and Busbar End Piece, these secure the depositor rod to the busbars.
D7097 − 19
FIG. 2 Sample Flask with Stirring Bar and Mantis Clip
6.1.1.15 Thermocouples, Two, stainless steel sheathed, 1.57 mm diameter by 150 mm length. One, a J-type, is used for
controlling the test temperature (depositor rod) while the other, a K-type, is used to protect against an over-temperature condition.
6.1.1.16 Thermocouple Locking Collar, a fitting that can be tightened on the thermocouple to ensure the thermocouple tip is at
the correct position when placed inside the depositor rod. (See Fig. 4.)
6.1.1.17 Volatiles Vial Clip, the device that holds the volatiles collection vial in place on the mantle. (See Fig. 4.)
6.1.2 Airflow Control Assembly, sets air flow at chosen flow rate.
6.1.2.1 Bubble Airflow Gauge, a device for precisely establishing the airflow rate and calibrating the flow meter from 1 mL ⁄min
to 30 mL ⁄min. (See Fig. 1.)
6.1.2.2 Calibrated Flow Meter, capable of measuring approximately 1 mL ⁄min to 20 mL ⁄min of air and providing a continuous
reading on airflow rate when calibrated.
6.1.2.3 Handheld Digital Flow Meter, an optional device to monitor air flow to or out of the mantle, capable of reading a flow
rate of 10.0 mL ⁄min 6 0.1 mL ⁄min of air.
6.1.2.4 Precision Digital Mass Flow Controller, an optional device that allows the precise control of the input air flow. (See Fig.
1a.)
6.1.2.5 Stopwatch, reading to 1/100 s.
6.1.3 Filtering Flask Assembly, provides the means for filtering particles washed from the depositor rod. (See Fig. 8.)
6.1.3.1 Filter Cartridge, a special multilayer filter made for the TEOST MHT procedure fitting the end of the filter funnel also
made for the TEOST procedure. (See Fig. 8.)
6.1.3.2 Filter Funnel, a special combination funnel of ~400 mL capacity, necking down to a 10 mL graduated or non-graduated
section that, in turn, ends in a glass or Luer-lock tip fitting the special filter cartridge used in the procedure. (See Fig. 8.)
6.1.3.3 Filter Tube Assembly, a metal or polyethylene tube inserted through a No. 8 rubber stopper in the vacuum flask to fit
the lower outlet of the filter cartridge. (See Fig. 8.)
6.1.3.4 Vacuum Flask, 1000 mL capacity for collecting the hydrocarbon solvent and oil during the filter rinse.
6.1.3.5 Vacuum Source, a vacuum source sufficient to draw the hydrocarbon solvent and oil through the filter and provide the
necessary filter drying.
6.1.3.6 Wire Rod, a thin, clean, stainless steel wire rod, for dislodging any deposits trapped in the narrow portion of the filter
funnel just above the filter.
6.2 Ancillary Equipment, needed or helpful:
6.2.1 Balance, capable of weighing deposits to the nearest 0.1 mg with a minimum capacity of 100 g.
6.2.2 Catalyst Syringe, a small glass syringe that uses either a glass or PTFE plunger (do not use rubber plunger) of 100 μL
capacity, for carefully metering the catalyst being weighed into the sample flask. (An optional approach is to use a small disposable
glass pipet.)
6.2.3 Oil Sample Transfer Pipettes, disposable glass or plastic pipettes or droppers.
6.2.4 Oil Extraction Test Tubes, three glass test tubes of sufficient height to cover all but the upper 20 mm of an inserted
deposit-carrying rod. Plastic tubes are not acceptable.
6.2.5 Temperature Recorder, an optional device for tracking the temperature of the upper depositor rod thermocouple over the
24 h period of the test.
6.2.6 Thermocouple Depth Insertion Gauge, an optional measurement device fabricated for simple setting and checking of the
thermocouple insertion depth, using a millimeter graduation scale.
6.2.7 Vials and Caps, a vial and matching cap of 10 mL or more in volume with an 11.5 mm diameter mouth and an outer
diameter of 20 mm to collect the volatile material emitted by the oil and collected on the mantle wall during the test as well as
the recovered, end-of-test oil sample. (See Fig. 4.)
6.2.8 Weighing Boat, a light, circular or oblong weighing container, preferably made of aluminum with a diameter or length of
7 cm to 10 cm and notched in two diametrically opposed places to prevent the rod from rolling. (Seerolling (see Fig. 3.)) or a
suitable weighing device capable of preventing the rod from rolling and from losing any deposits.
6.2.9 Air-Flow Restrictor—a small PTFE washer designed to limit the amount of air allowed to pass between the sample flask
and the drain on the lower end-cap.
D7097 − 19
FIG. 3 Weighing Boat and Rod
FIG. 4 Depositor Assembly (Cut-away View)
7. Reagents and Materials
7.1 Abrasive Paper, 800-grit emery (aluminum oxide).
7.2 Acetone, particle-free, reagent grade, for final cleaning of new depositor rods. (Warning—Flammable. Health hazard.)
7.3 Air, oil-free, clean, and dry, obtained from cylinder gas or house line, regulated to 15 kPa to 100 kPa (2 psi to 15 psi) at more
than 690 kPa (100 psi).
D7097 − 19
FIG. 5 Insertion of Oil Inlet Tube (Cut-away View)
7.4 Cyclohexane or Other Alkane Hydrocarbon Solvent, reagent grade. (Warning—Flammable.) Cyclohexane is the only
allowed naphthenic hydrocarbon. Do not use any aromatic hydrocarbons. Throughout the further description of the test, the solvent
selected is referred to as “hydrocarbon solvent.”
7.4.1 The volatility of the cyclohexane as the solvent ensures timely evaporation of the deposits on the rod and filter. If another
alkane hydrocarbon is used as the solvent, longer drying times may be required. The higher the purity of the solvent, the quicker
the solvent should evaporate.
7.5 Catalyst —Catalyst contains iron, lead, and tin in ratios chosen for emulating engine deposit conditions.
7.5.1 For long term storage, it is acceptable to refrigerate the catalyst until a few hours before use (let catalyst warm to room
temperature before opening to eliminate condensation). Temporary unopened storage, up to four weeks, may be at room
temperature.
7.6 Certified Reference Oils, certified low deposit fluid (LDF, about 10 mg to 15 mg), medium deposit fluid (MDF, about 40 mg
to 50 mg), and high deposit fluid (HDF, about 70 mg to 90 mg).
7.7 Combination Pump Calibration and Temperature Control Thermocouple Depth Setting Oil, TPC-1, a highly deposit-
resistant oil used in setting pump calibration and temperature control calibration without forming significant deposits on the
depositor rod during these calibrations.
7.8 Varnish Cleaning Liquid, used in cleaning varnish from mantle, end-caps, and other components of the equipment after test.
Other glass cleaners with varnish removing capabilities also may be used.
8. Programming the Apparatus
8.1 PID (proportional, integral, and derivative) Settings for Temperature Control—In order for the thermocouple sensitivity and
response values (PID settings) to have the minimum excursion from the temperature value desired during operation set them to
the following settings: Pb 160 Re: 1.0 Ra 0.1. See specified settings for a specific controller. See the individual unit Instrument
Manual for more details on the specific settings and on the adjustment technique.
8.2 Temperature Controller Setting—Set the temperature control program to maintain 285 °C for 24 h according to the
instructions in the Instrument Manual.
D7097 − 19
FIG. 6 Flexible Tube Connection to Oil Feed Tube and Sample
Flask Placement with Mantis Clip (Cut-away View)
FIG. 7 Front and Side Views of Upper Mantle End Cap Showing Air Inlet
8.3 If using a strip chart recorder, turn on the strip chart, set the chart speed to 1010 mm mm/h, ⁄h, but do not lower the pen(s)
or turn on the chart drive at this time.
8.4 If using other means of continuously recording temperatures, prepare these for receiving information.
9. Calibration and Standardization
9.1 Calibration of Air Flow Rate (alternative procedures, follow 9.1.1 and 9.1.2):
9.1.1 Calibration of Air Flow Rate Using a Mass Flow Controller:
9.1.1.1 Use the bubble gauge or other primary calibration device before each test semi-annually to check or calibrate a mass
flow controller.
(1) The TEOST MHT protocol is sensitive to flow rate, therefore primary calibration of mass flow meters or other forms of
air flow control such as analog or digital flow meters is desired to ensure proper flow rate.
D7097 − 19
FIG. 8 Filter Funnel Setup
NOTE 2—Models of some mass flow meters may permit adjustment of the readout to the calibration value when the appropriate air flow is reached.
9.1.2 Calibration of Air Flow Rate Using an Air Flow Meter:
9.1.2.1 Use the bubble gauge or other primary calibration device before each test tosemi-annually to check or calibrate analog
or digital flow meters (see Note 3).
9.1.2.2 Set up the bubble gauge and flow meter equipped with a fine needle valve as shown schematically in Fig. 1a with a
three-way stopcock or Fig. 1c with a ball valve.
NOTE 3—A handheld flow meter may also be used.
9.1.2.3 Connect the dry air source to the flow meter and set the source’s regulator to a pressure value no greater than allowed
by the tolerances of the flow meter used.
9.1.2.4 Insert the end of the air inlet tube into the soft rubber tubing attached to the bubble gauge and check that the joint is
leak tight with soap solution.
9.1.2.5 Adjust the flow meter rate and retest bubble rise rate to bring the flow rate to 10.0 mL ⁄min 6 0.2 mL ⁄min.
9.2 Oil Pump Rate Calibration—Follow the technique in the manufacturer’s Instrument Manual to set a test oil flow rate of
0.25 g ⁄min 6 0.01 g ⁄min.
9.3 Temperature Controller Setting—Follow the technique in the manufacturer’s Instrument Manual to set a test temperature of
285 °C on the temperature controller.
9.4 Calibration of Control Thermocouple:
D7097 − 19
FIG. 9 Lower End-cap Seal
9.4.1 Calibrate the depositor rod temperature control thermocouple in a liquid or sand bath maintained at 285 °C 6 50 °C and,
if necessary, adjust the temperature offset of the temperature controller to match the bath temperature for this thermocouple. In the
absence of either a liquid, block or sand bath, boiling distilled water may be used to calibrate at 100 °C. The temperature should
be able to be calibrated within 60.1 °C.
9.4.2 Before each reuse of the thermocouple, clean any corrosion or other deposits from the thermocouple surface using a fine
abrasive pad (500 grit or finer) or emery paper (800 grit). The resulting cleaned surface shall show bright metal, particularly in
the temperature-sensitive area at the end of the thermocouple. Do not overclean the thermocouple surface or use coarse abrasives,
as the thermocouple wall could be thinned and damaged.
9.5 Determination, Setting, and Use of Appropriate Position for the Temperature Control Thermocouple—Follow the technique
in the manufacturer’s Instrument Manual to find the hottest point within the bore of the depositor rod.
9.5.1 Insert the thermocouple gently (see Note 5) into the bore of the depositor rod to bring the collar into contact with the
emergent top of the rod when it is in position within the depositor rod casing assembly positioned in the busbars.
NOTE 4—The locking collar may slip if the thermocouple is forced into the depositor rod thus resulting in a wrong position for the temperature sensing
area of the thermocouple.
9.5.2 If desired, adjust the strip chart recorder or other temperature-recording device to record temperature sensed by the
temperature control thermocouple.
NOTE 5—Continuously record the temperature of the controlling thermocouple at maximum sensitivity setting to determine any aberration in
temperature during a run that may be caused by temporary electrical failure or brownout of the local power supply.
9.6 Install the over-temperature thermocouple according to the manufacturer’s Instrument Manual.
9.7 Standardize the TEOST MHT procedure using certified reference oils in accordance with Sections 10 and 15.
10. Instrument and Sample Preparation
10.1 Before testing unknown samples, confirm the functionality of the TEOST MHT instrument by testing one of the certified
reference oils (see 7.6). Choosing one of the certified reference oils mentioned in 7.6, follow the directions in Section 10.
D7097 − 19
10.2 Make sure that the TEOST heat switch is in the off position to prevent any accidental startup of the test. Then turn on the
main power switch and allow 30 min 30 min or more for the instrument electronics to warm up. Ensure that the pump switch is
off.
10.3 Make sure that the thermocouples are clean (see 9.4.2).
10.4 Invert both the catalyst vial and the oil container at least three times to ensure homogeneity of both components prior to
use.
10.5 Place a clean sample flask (see Fig. 2) on a precision balance and tare the balance (to bring the indicated mass of the
container to zero).
10.6 Using a microliter glass syringe that uses either a glass or PTFE plunger (do not use rubber plunger), or optional disposable
glass pipet, add the pre-calculated mass of catalyst required to make 8.5 g of sample-catalyst mixture based on the certified value
of the catalyst and record the mass to the nearest 0.0001 g. The range for the mass of catalyst to be added shall be 60.0003 g of
the mass required.
NOTE 6—The mass of oil required for the appropriate mixture of catalyst-to-oil ratio is stated on the label of the vial of certified catalyst.
10.7 Again, tare the balance and add the required mass of oil to the sample flask to make the sample-catalyst mixture total 8.5 g
6 0.05 g. The range for the mass of the oil to be added shall be 60.01 g of the mass required to obtain the catalyst/oil ratio shown
on the catalyst bottle. If more oil than required is added, make a new sample.
NOTE 7—An electronic file containing a generic calculation table to determine the appropriate catalyst/sample weights can be obtained from the ASTM
Test Monitoring Center.
10.8 Add a TFE-fluorocarbon-coated magnetic stirring bar to the sample flask, and place the flask on the magnetic stirrer
incorporated on the platform of the TEOST (or other appropriate magnetic stirrer) and stir for 30 min to 60 min. Do not heat the
mixture. Do not stir the mixture too vigorously, and particularly avoid creating a large vortex where the mixture may splash out.
Be sure to load the sample and start the test within 20 min of the completion of the mixing process.
NOTE 8—For planning purposes, the hardware setup and the finish of sample mixing can be arranged to coincide, so the test can be started in a shorter
preparation time.
11. Hardware Setup
11.1 Install new end-cap O-rings in both end-caps.
NOTE 9—At this point, any interest of the operator in determining the mass of volatiles, recovered end-of-test oil, and mantle deposits will require
weighing and recording the initial mass of the volatiles collection vial, the recovered oil vial, and the cleaned and dried mantle.
11.2 Using a gentle twisting motion, insert the upper end of the glass mantle squarely into the upper end-cap. Avoid chipping
the mantle glass, and make sure that the hole or window (see Fig. 5) in the upper mantle faces the corresponding oil feed tube
opening in the upper end-cap. Set this assembly aside in a safe place until required to complete the depositor rod casing assembly.
11.3 Cleaning and Weighing a Depositor Rod; Use of Weighing Boat:
11.3.1 Select a weighing boat (see Fig. 3) for the depositor rod and obtain the boat’s mass to 60.0001 g. Keep covered when
not in use to avoid contamination from particles falling from the air.
NOTE 10—If fluctuations are seen on the balance, momentarily touch the boat to a grounding pad to eliminate static.
11.3.2 Once the depositor rod preparation has begun, handle the rod with care and do not set the rod down except on the
weighing boat. Keep covered when not in use.
11.3.3 When handling and cleaning the wire-wound depositor rod, be careful not to distort the length and pitch of the wire coils.
NOTE 11—The wire coils on the depositor rod are preset to a specified pitch by the manufacturer and are adjusted to a tension to just be able to slide
up and down on the machined narrower section of the rod around which the wire coil is wrapped without being too loose.
11.3.4 Use hydrocarbon solvent, to rinse both the outside and inside of the rod. Use thin, solvent-resistant laboratory gloves or
finger cots when handling the rod to keep natural skin oils from affecting the mass of the rod.
NOTE 12—If the cots or gloves are chemically attacked by the hydrocarbon solvent, a film or residue will be left on the surface of the gloves.
11.3.5 Using a pipe cleaner soaked in acetone, swab the inside bore of the depositor rod by pushing the pipe-cleaner all the way
through the bore in one direction, then repeat the cleaning of the inside bore in the opposite direction with a fresh pipe cleaner
soaked in acetone. Exercise particular care in handling and cleaning the depositor rod during this stage, avoiding any distortion
of the wire coil.
11.3.6 Rinse the outside and the inside bore of the depositor rod with acetone using appropriate solvent-resistant gloves.
11.3.7 Vacuum-dry or blow clean, dry air on the inside of the depositor rod while holding it between the thumb and index
fingers. Dry the outside of the rod only by exposure to ambient air.
ASTM Test Monitoring Center, 6555 Penn Ave., Pittsburgh, PA 15206. www.astmtmc.cmu.edu.
D7097 − 19
11.3.8 Set the depositor rod down in the pre-weighed weighing boat from 11.3.1 (see Fig. 3). Weigh the depositor rod and boat
to a constant mass within 60.0001 g. Record this value as the initial depositor rod and boat mass. Subtract the boat mass from
the total mass for later determination of the depositor rod mass carrying deposits from the test.
11.3.9 After the boat and depositor rod masses have been obtained, put the covered boat aside for later use when the depositor
rod has completed its exposure to deposits for 24-h.24 h.
11.4 Completing the Depositor Rod Casing Assembly (see Figs. 4-6):
11.4.1 Pick up the pre-assembled mantle and upper end-cap (see 11.2) and carefully slide the depositor rod up through the
bottom of the glass mantle/upper-end-cap assembly until the end of the depositor rod emerges through the threaded stem of the
upper end-cap.
11.4.2 Place two new small O-rings on the emergent depositor rod.
11.4.3 Place one of the ceramic isolators over the top of the depositor rod with the wider diameter of the isolator facing the
O-rings. Pushing with the ceramic isolator, bring the O-rings in contact with the top of the threaded stem of the end-cap as shown
in Fig. 4.
11.4.4 Place an end-cap nut on the emergent depositor rod and insert the narrower diameter of the isolator through the clearance
hole in the nut. Finger-tighten the nut onto the threaded end-cap stem to compress the two-stacked O-rings around the depositor
rod thus sealing and insulating the depositor rod from the end-cap.
11.4.5 Make sure that the bottom of the depositor rod helical wire winding is resting on the bottom shoulder of the narrower
midsection of the rod.
11.4.6 Insert the bottom end of the depositor rod through the top of the lower end-cap and continue by inserting the lower end
of the mantle into upper end of the lower end-cap (see Figs. 4 and 5). Again, use a careful twisting motion so as not to stress or
fracture the glass mantle.
11.4.7 Repeat the same pro
...