Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D2935-96 – Standard Test Method Technical Guide
📐 Scope and Terminology
This standard, designated ASTM D2935-96 (Reapproved 2000), defines a test method for measuring the apparent density of industrial aromatic hydrocarbons. The result is expressed in pounds in air per U.S. gallon, using a hydrometer at a convenient temperature, and reported at any specified atmospheric temperature. The term “apparent density at 60°F” is specifically defined within this method as the weight in air of a unit volume of sample at 60°F, with the density of the ambient air assumed to be 0.0012 g/cm³.
Significance and Use: This method is intended for use on high-purity benzene, toluene, styrene, ortho-, meta-, and para-xylene, mixed xylenes, and cyclohexane. Its precision has been rigorously tested between 55 and 100°F. While it is a powerful tool for internal quality control and research and development work, it is not designed for setting purchase specifications, but rather for accurate and reproducible density determination.
⚙️ Apparatus and Test Procedure
| 🟦 Apparatus | 📏 Specification Requirement |
|---|---|
| Hydrometer | ASTM E 100 pounds per gallon series, with a range consistent with the material density (see Table below). |
| Thermometer | ASTM E 1 (Gas Calorimeter Inlet, 50F), graduated in 0.1°F divisions, covering the range of 54 to 101°F. |
| Cylinder | Clear glass or plastic, with a lip for convenient pouring. |
| 🟦 Hydrometer Range (lb/gal) | 📐 Typical Test Material |
|---|---|
| 6.0 – 7.0 | Cyclohexane |
| 7.0 – 8.0 | Toluene, Mixed Xylenes |
| 8.0 – 9.0 | Benzene, Styrene |
Procedure Overview: A hydrometer reading is taken at any convenient temperature. The difference between this reading and the tabulated apparent density value at that specific test temperature is calculated. This difference is then applied to the tabulated value at the desired reporting temperature to determine the corrected apparent density. For routine work, a single determination may suffice, but duplicate determinations are strictly required in case of dispute or for formal referee purposes.
📊 Precision, Bias, and Reporting
To determine conformance with this test method, all observed or calculated values must be rounded “to the nearest unit” in the last right-hand digit of the specification limit. This rounding procedure must strictly follow the methodology outlined in ASTM Practice E 29. The flexibility of the measurement procedure, allowing for readings at various temperatures, provides robust utility across diverse laboratory conditions.
⚠️ Hazard Information: Specific hazard statements are provided in Section 7 and Note 3 of the standard. The user is responsible for consulting and complying with OSHA Regulations, specifically 29 CFR paragraphs 1910.1000 and 1910.1200, to establish appropriate safety and health practices.
💡 Technical Tip: The precision of the method is such that single determinations may be acceptable for routine checks, but always perform duplicate analyses for official referee work. This ensures the highest level of accuracy and defensibility for the reported apparent density value.
❓ Frequently Asked Questions
🔍 What is the precise definition of “apparent density” used in D2935?
It is defined as the weight in air of a unit volume of sample at 60°F, expressed in pounds per U.S. gallon, assuming an air density of 0.0012 g/cm³.
💡 What is the validated temperature range for this test method?
The test method has been tested for precision and is validated between 55 and 100°F.
⚡ Which materials are explicitly included in the scope of this standard?
The primary scope covers high-purity benzene, toluene, styrene, o-, m-, p-xylene, mixed xylenes, and cyclohexane.
📌 When are duplicate determinations strictly required by this method?
Duplicate determinations are mandatory in the case of a dispute between parties or for formal referee purposes, as indicated in Section 11.1 of the standard.