Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D1701-95 – Standard Test Method Technical Guide
🧪 Scope and Significance of Scavenger Content Testing
ASTM D1701-95 outlines test methods for determining arc-formed gas scavengers in askarels. It specifically covers tin tetraphenyl, phenoxypropene oxide (1,2-epoxy-3-phenoxypropane), and dicyclodiepoxy carboxylate (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane-carboxylate).
Measuring scavenger content assesses protection against arc-formed gases and permits estimation of required makeup additive.
| 🟦 Scavenger Type | 📏 Common Name | 🔬 Identification Method |
|---|---|---|
| Organometallic | Tin Tetraphenyl | Crystallizes at -20°C |
| Epoxide A | Phenoxypropene Oxide | No rapid test (assumed if Tin neg.) |
| Epoxide B | Dicyclodiepoxy Carboxylate | No rapid test (assumed if Tin neg.) |
⚠️ Regulatory Note: Many askarels contain polychlorinated biphenyls (PCBs), the manufacture and sale of which have been prohibited in the U.S. since 1978. Users are responsible for following all applicable Federal, state, and local regulations regarding the use, handling, and disposal of askarels containing PCBs.
🔬 Methodology for Tin Tetraphenyl Analysis
Tin tetraphenyl is the only scavenger that can be rapidly identified. If a sample is cooled to -20°C, it separates from the fluid and appears as a crystalline layer on the surface.
The test for tin tetraphenyl measures reacted and total scavenger content. Reacted scavenger is determined by hydrolyzing the reaction product and titrating the resulting HCl with standard KOH. Total scavenger is measured by first reacting the specimen with dry HCl gas, then following the same titration. Unreacted scavenger is the difference between total and reacted values.
| 🛠️ Apparatus | 🎯 Specification |
|---|---|
| Separatory Funnel | Squibb, pear-shaped, 125-mL capacity, standard-taper joint |
| Gas Bubbling Assembly | Male joint with side-arm tube, capillary tip reaching within 1 cm of funnel bottom |
| Drying Tower | For drying air supply (sulfuric acid for HCl gas) |
💡 Technical Tip: Ensure dry HCl gas is thoroughly dried through a sulfuric acid tower before sample introduction. Strict adherence to ASTM D1193 reagent water is required to avoid compromising titration accuracy.
📊 Identification and Reagent Purity Considerations
Identifying the specific scavenger is the first critical step. A negative cooling test at -20°C indicates the fluid contains one of the epoxide scavengers (phenoxypropene oxide or dicyclodiepoxy carboxylate), which have specific test methods detailed in the standard.
The standard mandates reagent grade chemicals conforming to ACS specifications. Reagent grade water must conform to ASTM Specification D1193.
❓ Frequently Asked Questions
🔍 What is the purpose of measuring scavenger content in askarels?
Measurement of scavenger content indicates the amount of protection available against arc-formed gases and permits estimation of the amount of makeup additive required to maintain fluid performance.
⚡ How is total scavenger content determined for tin tetraphenyl?
Total scavenger is measured by first reacting the test specimen with dry hydrochloric acid gas, hydrolyzing the product, and titrating the resulting acid with a standard potassium hydroxide solution.
💡 What does a negative result in the cooling test indicate?
If a test specimen of askarel gives a negative result for tin tetraphenyl upon cooling to -20°C, it may be assumed to contain one of the epoxide scavengers: phenoxypropene oxide or dicyclodiepoxy carboxylate.
📌 What types of scavengers are covered under ASTM D1701-95?
The standard covers tin tetraphenyl, phenoxypropene oxide (1,2-epoxy-3-phenoxypropane), and dicyclodiepoxy carboxylate (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane-carboxylate).