Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D4746-20 – Standard Test Method Technical Guide
📊 Overview and Significance of D4746-20
ASTM D4746-20 is an empirical standard test method for the determination of quinoline insolubles (QI) in tar and pitch by pressure filtration. This test method yields results comparable to those obtained by Test Method D2318 and is essential for characterizing raw materials in the carbon and aluminum industries. The values stated in inch-pound units are regarded as the standard; SI units provided in parentheses are for information only.
⚠️ Safety Notice: This standard involves the use of hot quinoline and pressurized nitrogen gas. Specific hazard information is provided in Sections 6.2, 6.3, and 7 of the standard. Users must establish appropriate safety, health, and environmental practices prior to use.
⚙️ Apparatus and Test Procedure
The core apparatus consists of a stainless steel (304) jacketed pressure filtration vessel heated by steam or cooled with water. The sample is digested in hot quinoline and filtered under nitrogen pressure through a sealed system. The insoluble matter is retained on a 3A2 Berlin porcelain filtration crucible.
| 🟦 Component | 📐 Specification / Detail |
|---|---|
| Filtration Vessel | Stainless steel (304) jacketed block |
| Filtration Crucible | 3A2 Berlin porcelain |
| Sealing Mechanism | Flat gasket, clamp, three O-rings, crucible sealing collar, and adjustable plunger |
| Filtration Pressure | Nitrogen gas at 10 psig to 30 psig |
The procedure demands strict adherence to all details due to its empirical nature. The digested sample is filtered through the heated pressure filter. The retained insoluble material is washed with hot, fresh quinoline followed by cold acetone, then dried and weighed to determine the final QI content.
📈 Key Measured Properties and Compliance
The primary measured property is the weight percentage of quinoline-insoluble (QI) matter. This property is critical for evaluating and characterizing tar and pitch and plays a key role in establishing the uniformity of shipments and sources of supply.
| 🎯 Property | ⚡ Method Detail |
|---|---|
| Quinoline Insolubles (QI) | Determined as weight % of residue after digestion and pressure filtration |
| Comparable Method | Results are comparable to Test Method D2318 |
| Test Requirement | Empirical nature requires strict adherence to all procedural details |
💡 Key Insight: The empirical nature of this test cannot be overstressed. Factors such as the digestion temperature, the specific porosity of the 3A2 Berlin crucible, and the nitrogen filtration pressure (10 psig to 30 psig) heavily influence the final QI value. Consistent conditions are vital for obtaining comparable results.
📌 Compliance Note: This test method (D4746-20) is under the jurisdiction of ASTM Committee D02. Referenced documents include test methods for density (D70), water content (D95), distillation (D850), and sampling procedures for pitch (D4296).
❓ Frequently Asked Questions
🔍 What is the fundamental principle behind the D4746-20 test method?
The sample is digested in hot quinoline to dissolve the soluble components. The insoluble matter (QI) is then isolated by pressure filtration, washed with hot quinoline and cold acetone, dried, and weighed to determine its percentage by mass.
💡 What is the required crucible specification for this test?
The method specifically requires a 3A2 Berlin porcelain filtration crucible. This crucible is sealed within the stainless steel pressure vessel using three O-rings, a crucible sealing collar, and an adjustable plunger to prevent leakage.
⚡ How is the filtration driven in this standard?
Filtration is driven by nitrogen gas introduced through the lid of the pressure filter at a pressure strictly between 10 psig and 30 psig. The entire apparatus is a jacketed block that is heated by steam or cooled with water to maintain the required temperature.
📌 Are the metric values considered standard in D4746-20?
No. The values stated in inch-pound units are regarded as the standard. The SI (metric) values provided in parentheses throughout the standard text are mathematical conversions and are supplied for information only.