ASTM D7097 Standard Test Method for Determination of Moderately High Temperature Piston Deposits by Thermo-Oxidation Engine Oil Simulation Test - TEOST MHT
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 Oil Feed Tube, the avenue for oil to be delivered from the pump to the top of the depositor rod.
6.1.1.9 End cap O-rings, Large, Petroleum-resistant, create a seal between the end-caps and glass mantle. (See Fig. 5.)
6.1.1.10 End cap O-rings, Small, Petroleum- and Heat-resistant, creates an air and fluid seal between depositor rod and end-caps. (See Fig. 5.)
6.1.1.11 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.)
6.1.1.12 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.)
6.1.1.13 Stainless Steel Hex Screws and Busbar End Piece, these secure the depositor rod to the busbars.
6.1.1.14 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.
6.1.1.15 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.)
6.1.1.16 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 to 30 mL/min. (See Fig. 1.)
6.1.2.2 Calibrated Flow Meter, capable of measuring approximately 1 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 +/- 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, stainless steel, 1 to 1.5 mm diameter, 300 to 350 mm length, 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 syringe of 100 µL capacity, for carefully metering the catalyst being weighed into the sample flask.
6.2.3 Oil Sample Transfer Pipettes, disposable glass or plastic pipettes or droppers.
6.2.4 Oil Extraction Test Tubes, three, 120-mm tall, made of glass or hydrocarbon solvent-resistant plastic.
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 millimetre 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 to 10 cm and notched in two diametrically opposed places to prevent the rod from rolling. (See Fig. 3.)
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.
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 to 100 kPa (2 to 15 psi) at more than 690 kPa (100 psi).
7.4 Cyclohexane or Other Alkane Hydrocarbon Solvent of Equivalent Volatility, reagent grade. (Warning - Flammable.) Do not use naphthenic or aromatic hydrocarbons. Throughout the test, this solvent is referred to as "hydrocarbon solvent".
7.4.1 Discussion - The volatility of the alkane hydrocarbon solvent ensures timely evaporation of the deposits on the rod and filter.
7.5 Catalyst - Catalyst contains iron, lead, and tin in ratios chosen for emulating engine deposit conditions.
7.5.1 Discussion - 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 to 15 mg), medium deposit fluid (MDF, about 40 to 50 mg), and high deposit fluid (HDF, about 70 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.
