Chromel Thermocouple Wire,ASTM E230，1

### Technical Datasheet: Chromel Thermocouple Wire (Type K Positive Leg) **Classification:** Nickel-Chromium Thermocouple Alloy **Type:** K Thermocouple Positive Conductor (KP) **Standard:** ASTM E230/E230M **Common Designation:** Chromel® (90Ni-10Cr) --- #### 1.0 Introduction **Chromel** is the standardized positive leg material for Type K thermocouples, representing one of the most widely used base metal thermocouple systems globally. This nickel-chromium alloy, when paired with the negative leg Alumel (KN), creates a reliable and accurate temperature measurement system capable of operating from cryogenic temperatures up to 1260°C (2300°F). Chromel wire is specifically engineered to provide **stable thermoelectric properties, excellent oxidation resistance, and consistent performance** across its entire temperature range. --- #### 2.0 Chemical Composition (Weight %) | Element | Minimum | Maximum | Typical Value | Function | |---------|---------|---------|---------------|----------| | **Nickel (Ni)** | Balance | Balance | ~90% | Base element, thermoelectric properties | | **Chromium (Cr)** | 9.0 | 10.0 | 9.5 | Oxidation resistance, thermoelectric output | | **Iron (Fe)** | - | 0.5 | 0.2 | Controlled impurity | | **Silicon (Si)** | - | 0.5 | 0.2 | Oxidation resistance | | **Manganese (Mn)** | - | 0.5 | 0.1 | - | | **Carbon (C)** | - | 0.10 | 0.05 | - | | **Cobalt (Co)** | - | 0.2 | 0.1 | - | | **Other Elements** | - | 0.5 | 0.2 | - | *Note: The precise 90Ni-10Cr composition is critical for maintaining specified thermoelectric properties.* --- #### 3.0 Physical & Mechanical Properties | Property | Value | Condition/Notes | |----------|-------|-----------------| | **Density** | 8.73 g/cm³ | At room temperature | | **Melting Point** | 1427°C (2600°F) | - | | **Electrical Resistivity** | 0.71 μΩ·m | At 20°C | | **Thermal EMF** | +4.10 mV | At 100°C (relative to Pt-67) | | **Temperature Range** | -200°C to 1260°C | Continuous service | | **Curie Temperature** | 354°C (670°F) | Magnetic transition point | | **Tensile Strength** | 655-724 MPa | Annealed condition | | **Elongation** | 25-35% | Annealed condition | | **Thermal Conductivity** | 19.0 W/m·K | At 100°C | --- #### 4.0 Thermoelectric Properties **4.1 EMF Output (Reference Junction at 0°C):** | Temperature (°C) | EMF Output (mV) | |------------------|-----------------| | 0 | 0.000 | | 100 | 4.096 | | 200 | 8.138 | | 500 | 20.640 | | 1000 | 41.276 | **4.2 Accuracy Specifications (per ASTM E230):** - **Standard Grade:** ±2.2°C or ±0.75% (whichever is greater) - **Special Grade:** ±1.1°C or ±0.4% (whichever is greater) --- #### 5.0 Performance Characteristics **5.1 Advantages:** - Wide temperature range capability - Excellent oxidation resistance in clean atmospheres - High EMF output per degree temperature change - Good mechanical strength and durability - Cost-effective for general industrial applications - Reliable and repeatable performance **5.2 Limitations:** - Vulnerable to sulfur-containing atmospheres - Subject to "green rot" in low oxygen environments - Performance degradation in reducing atmospheres - Limited use in vacuum environments at high temperatures - Requires protection from certain chemical environments --- #### 6.0 Applications **6.1 Primary Application Areas:** - Industrial process control systems - Heat treatment furnaces and ovens - Power generation equipment monitoring - Chemical and petrochemical processing - Aerospace and automotive testing - Research and development laboratories - Food processing and packaging equipment **6.2 Specific Implementations:** - Furnace temperature profiling and control - Engine exhaust temperature measurement - Industrial heater monitoring systems - Boiler and steam system temperature control - Environmental chamber temperature verification - Manufacturing process monitoring --- #### 7.0 International Standards & Specifications **Primary Standards Compliance:** | Standard Organization | Standard Number | Title/Description | |----------------------|-----------------|-------------------| | **ASTM International** | ASTM E230/E230M | Standard Specification for Temperature-Electromotive Force Tables | | **International Electrotechnical Commission** | IEC 60584-1 | Thermocouples - EMF specifications and tolerances | | **International Electrotechnical Commission** | IEC 60584-2 | Thermocouples - Tolerances | | **American National Standards Institute** | ANSI MC96.1 | Temperature Measurement Thermocouples | | **British Standards Institution** | BS EN 60584-1 | Thermocouples - EMF specifications | **7.1 Tolerance Classifications:** - **Class 1 (Precision Grade):** ±1.5°C from -40°C to 375°C - **Class 2 (Standard Grade):** ±2.5°C from -40°C to 333°C --- #### 8.0 Wire Specifications & Configurations **8.1 Standard Wire Sizes Available:** - **AWG 8** (3.26 mm) - High temperature, heavy duty - **AWG 14** (1.63 mm) - General industrial use - **AWG 20** (0.81 mm) - Laboratory and general purpose - **AWG 24** (0.51 mm) - Space-constrained applications - **AWG 28** (0.32 mm) - Fast response requirements **8.2 Insulation Options:** - **PVC:** Maximum 105°C, general purpose - **Teflon/FEP:** Maximum 205°C, chemical resistance - **Fiberglass:** Maximum 480°C, high temperature - **Ceramic Fiber:** Maximum 1260°C, extreme temperature --- #### 9.0 Installation & Maintenance Guidelines **9.1 Best Practices:** - Use proper extension wire for long distance runs - Ensure clean, tight connections at all junctions - Avoid mechanical stress and vibration at measurement points - Use appropriate protection tubes in corrosive environments - Maintain proper grounding and shielding techniques **9.2 Common Failure Prevention:** - Protect from sulfur-containing atmospheres - Avoid temperature cycling beyond specifications - Prevent contamination during installation - Use adequate insulation in high-temperature applications - Regular calibration verification in critical applications --- **Note:** Chromel is a registered trademark of Hoskins Manufacturing Company. Type K thermocouples offer the widest temperature range of all common base metal thermocouple types. For optimal performance and accuracy, always follow manufacturer recommendations and industry best practices for installation and maintenance. Regular calibration and proper handling are essential for maintaining measurement accuracy over time.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3282 gallon liquid totes Special package is available on request.