ASTM D7097 Standard Test Method for Determination of Moderately High Temperature Piston Deposits by Thermo-Oxidation Engine Oil Simulation Test - TEOST MHT
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 MHT2) test method as derived from an interlaboratory study is approximately 10 to 100 mg. However, experience indicates that deposit values from 1 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 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. No other units of measurement are included in this standard.
1.3.1 The values stated in SI units are to be regarded as standard. Although not an SI unit, the special name, litre (L) is allowed by SI for the cubic decimetre (dm3) and the millilitre (mL) for the SI cubic centimetre (cm3).
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 and health practices and determine the applicability ofregulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D4485 Specification for Performance of Engine Oils
D6335 Test Method for Determination of High Temperature Deposits by Thermo-Oxidation Engine Oil Simulation Test
3. Terminology
3.1 Definitions ofTerms Specific to This Standard:
3.1.1 bubble airflow gauge, n - a precision bore glass tube marked in tenths of a millilitre 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.
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).