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D5661-95 – Standard Test Method Technical Guide
ASTM D5661-95 (Reapproved 2001) outlines a test method for determining the relative solvency of petroleum oils used in ink formulations through a pentaerythritol ester of resin acids (PKP) titration method. This standard is essential for ensuring compositional consistency in petroleum oils and differentiating between hydrotreated and non-hydrotreated oils with similar viscosity.
📐 Test Overview and Scope
This test method applies to petroleum oils with an initial boiling point over 90°C and a dry point under 500°C as determined by Method D86. The PKP value, defined as the volume in millilitres of pentane required to produce a defined turbidity in a mixture of 10 g of test oil and 5 g of a standard PKP solution at 25±2°C, serves as a key indicator of solvency. High PKP values suggest high aromatic or naphthenic content, contributing to greater relative solvency.
The method is used alongside kinematic viscosity measurements from Test Method D445 to ensure compositional consistency and can differentiate between oil types. Safety precautions are necessary due to the use of pentane, a flammable chemical designated by OSHA. Users must establish appropriate safety and health practices and determine regulatory applicability before use.
⚙️ Apparatus and Reagents
The standard specifies precise equipment for the titration procedure, ensuring accurate and reproducible results. The following are required for testing:
| 🛠️ Equipment | 📏 Specification |
|---|---|
| Magnetic Stirrer | With stir bar |
| Erlenmeyer Flask | 1000-mL capacity |
| Glass Beaker | 250-mL capacity |
| Burette | 50-mL capacity |
| Print Specimen | 152 x 152 mm sheet of newspaper with 10-point type |
| Analytical Balance | 100-g capacity, reproducibility 0.01 g |
| Sieve Screen | 10 mesh |
Reagent grade chemicals are required, including toluene and pentane. A 40% by weight solution of PKP in toluene is used for standardization, with toluene-heptane solutions employed during the process.
📊 Test Procedure and Significance
The test begins by standardizing a 40% PKP solution in toluene in two steps: mixing with toluene and titrating with pentane, and also mixing with a toluene-heptane solution and titrating until a turbidity end point is reached. The standardized PKP solution is then mixed with the test oil and titrated with pentane until the same end point is achieved. The result is expressed in millilitres of pentane.
PKP values indicate high aromatic or naphthenic content, which contributes to high relative solvency of the oil. This method, combined with viscosity measurements, ensures compositional consistency and can differentiate between hydrotreated and non-hydrotreated oils with the same viscosity.
⚠️ Warning: Pentane is a flammable chemical as designated by OSHA. Always consult the supplier’s Material Safety Data Sheet for specific hazard information and guidance. Establish appropriate safety and health practices before use, including proper ventilation and handling procedures.
💡 Tip: For comprehensive compositional consistency, use this test method in conjunction with viscosity measurements from ASTM D445. The PKP value, combined with viscosity data, provides robust quality control for petroleum oils in ink formulations.
❓ Frequently Asked Questions
🔍 What is the PKP value of a solvent?
According to ASTM D5661, the PKP value is the volume in millilitres, at 25±2°C, of pentane required to produce a defined degree of turbidity in a mixture containing 10 g of the test oil and 5 g of a standard solution of a pentaerythritol ester of resin acids in toluene.
💡 Why is this test method significant?
This test method is crucial for determining the relative solvency of petroleum oils used in ink formulations. PKP values indicate high aromatic or naphthenic content, which contributes to high relative solvency. It is also used to ensure compositional consistency when combined with viscosity measurements.
⚡ What are the safety concerns regarding pentane?
Pentane is classified as a flammable chemical by OSHA. Users should consult the Material Safety Data Sheet for specific hazard information and establish appropriate safety protocols, including handling, storage, and disposal precautions to minimize risks.
📌 How is the test result expressed?
The test result is expressed as millilitres of pentane required to reach the turbidity end point during titration. This value directly reflects the relative solvency of the petroleum oil tested.