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D120-22 – Standard Test Method Technical Guide
📐 Types and Classes of Rubber Insulating Gloves
ASTM D120-22 specifies rubber insulating gloves for worker protection from electrical shock. Two types are defined: Type I is non-resistant to ozone, while Type II is resistant to ozone. Six classes, Class 00 through Class 4, provide varying levels of electrical protection based on their dielectric strength.
| 🟦 Type | 📏 Description |
|---|---|
| Type I | Non-resistant to ozone |
| Type II | Resistant to ozone |
Each class has unique electrical characteristics; refer to the standard for specific proof test voltage ratings and maximum use voltages.
⚙️ Testing and Physical Property Requirements
The standard mandates several test methods from ASTM references to ensure glove performance. These include D412 for tensile strength, D624 for tear strength, D573 for oven aging, D1415 for International hardness, and D2240 for Durometer hardness. Additional chemical analysis is covered under D297. Compliance with these methods verifies mechanical integrity under electrical stress.
| 🛠️ Test Method | 🎯 Property Measured |
|---|---|
| D412 | Tensile strength and elongation at break |
| D624 | Tear strength |
| D1415 | International hardness |
| D2240 | Durometer hardness |
📊 Key Definitions and Specifications
Important terminology includes “working area,” which encompasses all finger and thumb crotches, the palm, and the areas facing the palm not extending beyond the center line of the crotch. “Halogenation treatment” exposes the entire glove surface to a halogen for reduced friction, while “glove cuff roll” refers to the reinforced edge at the cuff. “Ozone” is a highly active form of oxygen that may be produced by corona or arcing, influencing glove type selection.
⚠️ Warning: This standard does not purport to address all safety concerns, if any, associated with its use. It is the responsibility of the user to establish appropriate safety, health, and environmental practices (see Section 1.5).
💡 Tip: For environments with potential ozone exposure, Type II gloves are recommended to enhance longevity and safety, as they are specifically formulated to resist ozone degradation.
❓ Frequently Asked Questions
🔍 What is the difference between Type I and Type II gloves?
Type I gloves are non-resistant to ozone, whereas Type II gloves are resistant to ozone, making them suitable for work areas with corona, arcing, or ultraviolet rays that generate ozone.
💡 How many classes of rubber insulating gloves are defined?
There are six classes: Class 00, Class 0, Class 1, Class 2, Class 3, and Class 4. These differ in electrical characteristics for protection at varying voltage levels.
⚡ What is halogenation treatment used for?
Halogenation treatment reduces surface friction on the entire glove area, making it easier to don and doff without compromising the glove’s electrical or physical properties.
📌 What does the term “working area” refer to?
The working area includes all finger and thumb crotches, the palm, and the area of the finger and thumb facing the palm, not extending beyond the center line of the crotch, as illustrated in Fig. 1 of the standard.