ASTM D240 for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter
1. Scope
1.1 This test method covers the determination of the heat of combustion of liquid hydrocarbon fuels ranging in volatility from that of light distillates to that of residual fuels.

1.2 Under normal conditions, this test method is directly applicable to such fuels as gasolines, kerosines, Nos. 1 and 2 fuel oil, Nos. 1-D and 2-D diesel fuel and Nos. 0-GT, 1-GT, and 2-GT gas turbine fuels.

1.3 This test method is not as repeatable and not as reproducible as Test Method D4809.

1.4 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only.

1.5 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 of regulatory limitations prior to use. For specific hazard statements, see Sections 7 and 9 and A1.10 and Annex A3.

2. Referenced Documents
2.1 ASTM Standards:
D129 Test Method for Sulfur in Petroleum Products (General Bomb Method)
D1018 Test Method for Hydrogen In Petroleum Fractions
D1266 Test Method for Sulfur in Petroleum Products (Lamp Method)
D2622 Test Method for Sulfur in Petroleum Products by Wavelength Dispersive X-ray Fluorescence Spectrometry
D3120 Test Method for Trace Quantities of Sulfur in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry
D3701 Test Method for Hydrogen Content of Aviation Turbine Fuels by Low Resolution Nuclear Magnetic Resonance Spectrometry
D4294 Test Method for Sulfur in Petroleum and Petroleum Products by Energy Dispersive X-ray Fluorescence Spectrometry
D4809 Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimeter (Precision Method)
D5453 Test Method for Determination of Total Sulfur in Light Hydrocarbons, Spark Ignition Engine Fuel, Diesel Engine Fuel, and Engine Oil by Ultraviolet Fluorescence
E 1 Specification for ASTM Liquid-in-Glass Thermometers
E 200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis

3. Terminology
3.1 Definitions:
3.1.1 gross heat of combustion, Qg (MJ/kg) - the quantity of energy released when a unit mass of fuel is burned in a constant volume enclosure, with the products being gaseous, other than water that is condensed to the liquid state.
3.1.1.1 Discussion - The fuel can be either liquid or solid, and contain only the elements carbon, hydrogen, nitrogen, and sulfur. The products of combustion, in oxygen, are gaseous carbon dioxide, nitrogen oxides, sulfur dioxide, and liquid water. In this procedure, 25°C is the initial temperature of the fuel and the oxygen, and the final temperature of the products of combustion.

3.1.2 net heat of combustion, Qn (MJ/kg) - the quantity of energy released when a unit mass of fuel is burned at constant pressure, with all of the products, including water, being gaseous.
3.1.2.1 Discussion - The fuel can be either liquid or solid, and contain only the elements carbon, hydrogen, oxygen, nitrogen, and sulfur. The products of combustion, in oxygen, are carbon dioxide, nitrogen oxides, sulfur dioxide, and water, all in the gaseous state. In this procedure, the combustion takes place at a constant pressure of 0.1012 MPa (1 atm), and 25°C is the initial temperature of the fuel and the oxygen, and the final temperature of the products of combustion.

3.1.3 The following relationships may be used for converting to other units (conversion factor is exact only for Btu):
1 cal (International Table calorie) = 4.1868 J
1 Btu (British thermal unit) = 1055.06 J and refer to as factor not exact
1 cal (I.T.)/g = 0.0041868 MJ/kg
1 Btu/lb = 0.002326 MJ/kg

3.2 Definitions of Terms Specific to This Standard:
3.2.1 energy equivalent - (effective heat capacity or water equivalent) of the calorimeter is the energy required to raise the temperature 1° expressed as MJ/°C.
1 MJ/kg = 1000 J/g

In SI, the unit of heat of combustion has the dimension J/kg, but for practical use a multiple is more convenient. The MJ/kg is customarily used for the representation of heats of combustion of petroleum fuels.

NOTE 1 - The energy unit of measurement employed in this test method is the joule with the heat of combustion reported in megajoules per kilogram.

3.3 Symbols:
3.3.1 The net heat of combustion is represented by the symbol Qn and is related to the gross heat of combustion by the following equation:
Qn (net, 25°C) = Qg (gross, 25°C) - 0.2122 x H
where:
Qn (net, 25°C) = net heat of combustion at constant pressure, MJ/kg,
Qg (gross, 25°C) = gross heat of combustion at constant volume, MJ/kg, and
H = mass % of hydrogen in the sample.