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D3338 – Standard Test Method Technical Guide
📐 Scope and Applicability
This test method covers the estimation of the net heat of combustion of aviation gasolines and aircraft turbine and jet engine fuels. It is applicable to liquid hydrocarbon fuels that conform to specifications for Jet A, Jet A-1, Jet B, JP-4, JP-5, JP-7, and JP-8, as well as aviation gasolines grades 100/130 and 115/145.
The net heat of combustion range is from 40.19 MJ/kg to 44.73 MJ/kg (or 17,280 Btu/lb to 19,230 Btu/lb). The precision for estimation outside this range has not been determined for this test method.
⚙️ Test Procedure and Correlation
This test method is purely empirical and is based on a correlation from experimental data on heat of combustion, obtained by a precision method similar to Test Method D4809. The estimation of net heat of combustion is justified only when the fuel belongs to a well-defined class for which a relation between heat of combustion and aromatic and sulfur contents, density, and distillation range has been derived.
The correlation uses property ranges including aromatics from 0% to 100% by mass, API gravity from 25.7° to 81.2°API, and average boiling point from 160°F to 540°F. Users should recognize that estimates may be in error by large amounts for individual fuels.
📊 Key Measured Properties
The following table summarizes the property ranges used in the correlation for estimating net heat of combustion.
| 🟦 Property | 📏 Value Range | 📐 Units |
|---|---|---|
| Aromatics Content | 0 to 100 | % by mass |
| API Gravity | 25.7 to 81.2 | °API |
| Average Boiling Point | 160 to 540 | °F |
These ranges are based on experimental data from representative samples including kerosenes, alkylates, pure hydrocarbons, and reports from the Coordinating Research Council.
Tip: For best results, ensure that the fuel sample is within the specified property ranges and belongs to the defined class of fuels mentioned in the standard. SI units are preferred for calculations.
Warning: The empirical nature of this test method means that estimates may have significant errors for individual fuels. Always verify with precise test methods like D4809 when accuracy is critical.
❓ Frequently Asked Questions
🔍 What fuels are covered by ASTM D3338?
ASTM D3338 covers aviation gasolines and aircraft turbine and jet engine fuels such as Jet A, Jet A-1, Jet B, JP-4, JP-5, JP-7, and JP-8.
💡 Can this method be used for fuels outside the specified range?
No, the precision for estimation has not been determined for net heat of combustion outside 40.19 MJ/kg to 44.73 MJ/kg (or 17,280 Btu/lb to 19,230 Btu/lb).
⚡ What are the key parameters in the correlation?
The correlation uses aromatics content, API gravity, and average boiling point within specific ranges as detailed in the standard.
📌 How does D3338 relate to other test methods?
D3338 does not require aniline point, unlike D1405 and D4529. Both D1405 and D4529 offer similar precision with different calculation approaches.