ASTM 909 Standard Test Method for Supercharge Rating of Spark-Ignition Aviation Gasoline
7. Apparatus
7.1 Engine Equipment - This test method uses a single cylinder, CFR engine that consists of standard components as follows: crankcase, a cylinder/clamping sleeve, a thermal siphon recirculating jacket coolant system, an intake air system with controlled temperature and pressure equipment, electrical controls, and a suitable exhaust pipe. The engine flywheel is connected to a special electric dynamometer utilized to both start the engine and as a means to absorb power at constant speed when combustion is occurring (engine firing). See Fig. 1 and Table 1.
7.1.1 The CFR Engines, Inc. designation for the apparatus required for this test method is Model CFR F-4 Supercharge Method Octane Rating Unit.
7.2 Auxiliary Equipment - A number of components and devices have been developed to integrate the basic engine equipment into complete laboratory measurement system.
8. Reference Materials
8.1 Cylinder Jacket Coolant - Ethylene Glycol shall be used in the cylinder jacket with the required amount of water to obtain a boiling temperature of 191 °C +/- 3 °C (375 °F +/- 5 °F). (Warning - Ethylene glycol based antifreeze is poisonous and may be harmful or fatal if inhaled or swallowed. See Annex A1.)
8.1.1 Water shall be understood to mean reagent water conforming to Type IV of Specification D1193.
8.2 Engine Crankcase Lubricating Oil - An SAE 50 viscosity grade oil meeting the current API service classification for spark-ignition engines shall be used. It shall contain a detergent additive and have a kinematic viscosity of 16.77 mm2/s to 25.0 mm2/s (cSt) at 100 °C (212 °F) and a viscosity index of not less than 85. Oils containing viscosity index improvers shall not be used. Multigraded oils shall not be used. (Warning - Lubricating oil is combustible and its vapor is harmful. See Annex A1.)
8.3 PRF, isooctane (2,2,4-trimethylpentane) and n-heptane meeting the specifications in Table 2. (Warning - Primary reference fuel is flammable and its vapors are harmful. Vapors may cause flash fire. See Annex A1.)
8.4 Tetraethyllead concentrated antiknock mixture (aviation mix) containing not less than 61.0 weight % of tetraethyllead and sufficient ethylene dibromide to provide two bromine atoms per atom of lead. The balance of the antiknock mixture shall be a suitable oxidation inhibitor, an oil-soluble dye to provide a distinctive color for identification, and kerosene.
8.4.1 Temperature Corrections - If the temperature of the fuel is below that of the TEL, the quantity of the TEL is increased and vice versa as calculated by the coefficient of expansion, obtained from the supplier, of concentrated TEL.
8.4.2 Analysis for TEL - It is recommended that each blend of fuel, particularly drum blends, be analyzed for lead content in accordance with standard test methods (see Test Methods D3237, D3341, and D5059.)
8.5 Isooctane+6.0 mL TEL - a mixture of isooctane and aviation mix tetraethyllead that contains 6.00 mL +/- 0.05 mL of tetraethyllead per U.S. gallon (1.68 g +/- 0.014 g of elemental lead per litre) which may be blended with isooctane to prepare reference fuel blends.
8.5.1 Blend ratios for diluting isooctane+6.0 mL TEL with isooctane to prepare the reference fuel compositions that are employed in this test method are shown in Table 3.
