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D1933-03 – Standard Test Method Technical Guide
🧾 Standard Overview and Nitrogen Types
The ASTM D1933-03 (Reapproved 2017) specification defines nitrogen gas used as an electrical insulating material in electrical equipment. It covers three types of nitrogen obtained from air liquefaction processes:
Type I: Dried after liquefaction.
Type II: Deoxidized with hydrogen over a platinum catalyst and dried.
Type III: Deoxidized by suitable means if necessary.
Note that while metal containers meet this specification, contamination with unlisted impurities is possible. The standard includes a safety hazards caveat for test methods.
📊 Composition and Properties
Samples must conform to Table 1 requirements. Key properties and test methods:
| 🟦 Property | 📏 Test Method | 🎯 Requirement |
|---|---|---|
| Nitrogen & Rare Gases | Calculation by difference after O₂ and H₂ analysis | Balance |
| Hydrogen | Practice E260 or mutual agreement | As specified per type |
| Oxygen | Practice E260 or mutual agreement | As specified per type |
| Water Vapor (Dew Point) | Test Methods D2029 | As specified per type |
Specific limits are detailed in the full standard for each nitrogen type.
⚙️ Sampling, Test Methods, and Shipping
For nitrogen gas in high-pressure containers, extract specimens using a dual-stage regulator reducing 15 MPa (2200 psi) to low pressure. For liquid nitrogen used as gas, use a single-stage regulator with 1.7 MPa (250 psi). Ensure clean, dry tubing and purge apparatus thoroughly. Follow Practice E105 for multiple cylinder sampling. Test hydrogen and oxygen via Practice E260, and dew point via D2029. Package nitrogen in DOT-approved metal containers, dry and free from oil and corrosive chemicals.
❓ Frequently Asked Questions
🔍 What are the three types of nitrogen in D1933-03?
Type I: Dried; Type II: Deoxidized with hydrogen over platinum catalyst and dried; Type III: Deoxidized by suitable means.
💡 How to sample gas from high-pressure containers?
Use a dual-stage regulator for 15 MPa (2200 psi) with clean, dry tubing and purge system before sampling.
⚡ Which test method is used for hydrogen analysis?
Practice E260 for gas chromatography or a mutually agreed method.
📌 What are shipping requirements for nitrogen?
DOT-approved cylinders, dry and free from oil and corrosive chemicals.
⚠️ Safety Note: This standard does not address all safety concerns. Users must establish appropriate health practices and regulatory compliance prior to use.
💡 Tip: The dew point test per D2029 is critical for ensuring low moisture in insulating nitrogen, which affects electrical performance.