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D1018-11 – Standard Test Method Technical Guide
📋 Scope and Significance
ASTM D1018-11 (Reapproved 2016) is a standard test method for determining hydrogen content in petroleum fractions that can be burned completely without smoking in a wick lamp. The values stated in SI units are to be regarded as standard. Knowledge of hydrogen content is essential for assessing performance characteristics of petroleum products, particularly fuels. This method is applicable for most laboratory determinations of hydrogen in liquid petroleum lubricants and products. It is approved for use by agencies of the U.S. Department of Defense.
⚙️ Apparatus and Test Procedure
The test involves burning the specimen from a cotton wick in purified air. Combustion gases are passed through absorption bulbs where water vapor is collected by a desiccant and subsequently weighed. The apparatus comprises a lamp with a 25 mL Erlenmeyer flask, a burner with concentric glass tubes and a small opening for pressure equalization, and a chimney constructed as per Appendix A3 of Test Method D1266, with modifications. Absorption bulbs are filled in layers: bottom 1–2 cm glass wool, 5 cm of 6–10 mesh anhydrous calcium chloride, 1 cm glass wool, 2 cm phosphorus pentoxide, and glass wool to the top. One filling suffices for approximately 10 g of water. The cotton wicking must be clean, unused, uniform, two-strand twisted, weighing 0.5 g/m to 0.6 g/m per strand.
⚠️ Compressed air for combustion is under high pressure; ensure proper handling and safety measures.
📊 Key Specifications and Data
The absorption bulb filling specifications are critical for accurate water collection:
| 🟦 Layer | 📏 Thickness (cm) | 📐 Description |
|---|---|---|
| Glass wool (bottom) | 1–2 | Layer at the base |
| Anhydrous calcium chloride | 5 | 6–10 mesh, cp grade |
| Glass wool | 1 | Separator layer |
| Phosphorus pentoxide | 2 | Desiccant layer |
| Glass wool (top) | To fill | Fills remaining space |
The cotton wicking specifications are equally important:
| 🟦 Property | 📏 Specification |
|---|---|
| Type | Two-strand twisted cotton |
| Weight per strand | 0.5 g/m to 0.6 g/m |
| Quality | Clean, unused, uniform |
💡 Turner-type absorption bulbs are recommended for this test method.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D1018-11?
It covers hydrogen determination in petroleum fractions that burn completely without smoking in a wick lamp.
💡 How is the water formed collected?
The water from combustion gases is collected by a desiccant in absorption bulbs and weighed.
⚡ What are the wicking specifications?
Wicking must be clean, unused, two-strand twisted cotton, weighing 0.5 g/m to 0.6 g/m per strand.
📌 What safety concerns are noted?
Compressed air is under high pressure; users should establish appropriate safety practices.