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D3505-18 – Standard Test Method Technical Guide
📐 Scope and Applicability
This test method describes a simplified procedure for the measurement of density or relative density of pure liquid chemicals for which accurate temperature expansion functions are known. It is restricted to liquids having vapor pressures not exceeding 79,993 Pa (0.800 bar, 600 mm Hg, 0.789 atm) at the equilibration temperature, and having viscosities not exceeding 15 cSt at 20 °C.
Results can be reported in density (g/cm³ or g/mL at 20 °C) and relative density (20 °C/4 °C or 15.56 °C/15.56 °C). The method is based on the old definition of the litre, where 1 L = 1.000028 dm³, but now 1 mL = 1 cm³ exactly.
⚠️ Liquid Restrictions: Vapor pressure must not exceed 79,993 Pa and viscosity must not exceed 15 cSt at 20 °C for accurate results.
⚙️ Test Procedure and Equipment
The specified procedure uses a beam balance to determine weight, avoiding corrections for gravity variations. When torsion or spring balances are used, corrections are necessary. The test requires accurate control of equilibration temperature and knowledge of temperature expansion functions for the liquid.
Referenced standards such as D3437 for sampling handling and D6809 for quality assurance provide additional guidance. The method is suitable for liquids with viscosities ≤ 15 cSt at 20 °C and vapor pressures ≤ 79,993 Pa.
💡 Historical Note: This test method is based on the old definition of 1 L = 1.000028 dm³. In 1964, the definition was changed so that 1 mL = 1 cm³ exactly. Ensure consistency when comparing with modern data.
📊 Key Measured Properties
The test method allows reporting in various units, as shown in the table below. Results should be rounded off in accordance with Practice E29.
| 🏷 Measurement | 📏 Reference Temperature | 🐐 Unit |
|---|---|---|
| Density | 20 °C | g/cm³ or g/mL |
| Relative Density | 20 °C/4 °C | dimensionless |
| Relative Density | 15.56 °C/15.56 °C | dimensionless |
For alternative methods, see Test Method D4052 for relative density determination using a digital density meter.
❓ Frequently Asked Questions
🔍 What is the purpose of ASTM D3505-18? It provides a simplified method for measuring density or relative density of pure liquid chemicals with known temperature expansion functions.
💡 What are the liquid restrictions for this test method? Liquids must have vapor pressures ≤ 79,993 Pa and viscosities ≤ 15 cSt at 20 °C to be eligible.
⚡ How is mass determined in the test method? A beam balance is used to avoid correction for gravity; otherwise, corrections are applied for other balance types.
📌 What units can be reported for density and relative density? Density can be reported in g/cm³ or g/mL at 20 °C, and relative density at 20 °C/4 °C or 15.56 °C/15.56 °C.