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D3802-23 – Standard Test Method Technical Guide
📐 Scope and Terminology
This test method, designated D3802‑23, provides a procedure for determining the ball‑pan hardness number of granular activated carbons. It is applicable to carbons where 90 % of particles exceed 80 mesh (180 µm) as per Test Method D2862. The standard includes definitions for nominal particle size for natural and pelleted carbons, as described in Terminology D2652.
| 🟦 Carbon Type | 📏 Small End Exclusion | 📐 Large End Exclusion |
|---|---|---|
| Natural, Granular, Irregular | Not more than 5 % | Not more than 5 % |
| Pelleted Carbons | Not more than 10 % | Not more than 5 % |
These definitions ensure consistent particle size characterization for testing.
⚙️ Test Procedure and Equipment
The test involves placing a screened and weighed sample of activated carbon into a brass hardness pan along with a specified number of stainless steel balls. The pan is subjected to a combined rotating and tapping action for 30 minutes. After this period, the degree of particle size degradation is determined by weighing the carbon retained on a sieve with openings approximately half the minimum nominal particle size of the original sample.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Test Duration | 30 minutes |
| Pan Material | Brass (conforming to B19) |
| Ball Material | Stainless steel (conforming to B150/B150M) |
| Sample Particle Size | ≥90 % > 80 mesh (180 µm) |
| Sieve Opening (retention) | ≈½ of minimum nominal particle size |
The referenced standards for equipment ensure consistency and accuracy in test results.
📊 Significance and Key Measured Properties
The ball‑pan hardness test measures the resistance of activated carbon to particle size degradation under service conditions. It is one of several methods, including stirring bar and dust elutriation methods, used to evaluate carbon durability. The test results help predict performance in applications where attrition resistance is critical. The key measured property is the weight fraction of carbon retained on the specified sieve after the test, which indicates the material’s hardness.
💡 Tip: Ensure the sample is properly screened and representative per Practice E300 to avoid biased results.
⚡ Note: The test conditions (rotating and tapping) may not replicate all service conditions. Consider complementary tests like stirring bar or dust elutriation for comprehensive evaluation.
❓ Frequently Asked Questions
🔍 What is the purpose of the ball‑pan hardness test?
It determines the resistance of granular activated carbon to particle size degradation under simulated mechanical agitation.
💡 How is the test performed?
A weighed sample is placed in a brass pan with stainless steel balls, subjected to rotating and tapping for 30 minutes, and then the retained carbon on a half‑size sieve is weighed.
⚡ What equipment is specified for this test?
Equipment includes a brass hardness pan (per B19), stainless steel balls (per B150/B150M), a rotating‑tapping machine, and sieves conforming to Specification E11.
📌 What does the test result indicate?
The result indicates the hardness of the carbon, with higher retention weight suggesting greater resistance to degradation.