KP/KN Pin Type K Thermocouple Connector (Chromel-Alumel Contact Pins)

Thermocouple k-type KP KN chromel alumel alloy

1. Material Composition & Properties

Leg Alloy Designation Chemical Composition Key Characteristics

Positive (KP) Chromel Equivalent Ni 89-91%, Cr 9-10%, Si/Mn ≤1% Non-magnetic, resistivity 0.71 μΩ·m

Negative (KN) Alumel Equivalent Ni 94-97%, Al 1.5-2.5%, Mn 1.5-2.5%, Si ≤1% Magnetic, resistivity 0.23 μΩ·m

2. Performance Specifications

Parameter Value Standard/Notes

Temp Range (Wire Grade) Short-term: -200°C to 1,300°C Max 1,260°C per IEC 60584-1

Long-term:0°C to 1,100°C Optimal stability range

Temp Range (Extension) 0°C to 200°C Limited accuracy beyond 200°C

EMF Output 41 µV/°C at 1,000°C Vs. Platinum 67 reference

Accuracy (Class 1) ±1.5°C or ±0.4% (>0°C) Whichever greater

±2.5°C (-200°C to 0°C) Cryogenic tolerance

Oxidation Resistance Superior to Type J/T/E below 1,000°C Cr2O3 protective layer

3. Environmental Compatibility & Restrictions

Recommended Atmospheres:

• Oxidizing: Air, combustion exhausts (electric furnaces)
• Inert Gases: Argon, nitrogen (full performance up to 1,100°C)

Prohibited Conditions:

Scenario Failure Mechanism Mitigation

Sulfur-containing gases Sulfidation → brittle fracture Avoid H2S/SO2 environments

Alternating redox cycles Calibration drift >5°C Use Type N in cyclic apps

Vacuum >1 hour (>800°C) Chromium vaporization Max 60-min exposure

H2/CO atmospheres Green Rot corrosion (815-1040°C) Ceramic protection tubes

4. Competitive Advantages

• Cost Efficiency: 30–50% cheaper than noble-metal types (R/S/B)
• Radiation Hardness: Preferred in nuclear applications vs. Type J
• Lifetime: 5× longer than Type J at 900°C (Fe oxidation in J)

5. Precision Tolerance Standards

Class Tolerance Formula Application Context

Class 1 ±1.5°C or ±0.004×|t| (°C) Aerospace, calibration labs

Class 2 ±2.5°C or ±0.0075×|t| (°C) Industrial process control

|t| = Absolute temp in °C; Special Error Grade (±0.4%) available for high-precision needs

Supplemental Technical Notes

Connection Best Practices:

• Use MgO-insulated nickel-alloy extension wires for EMF stability
• Avoid copper terminals → galvanic corrosion in humid environments

Aging Prevention:

• Pre-aging at 850°C for 2 hrs reduces drift in precision sensors

Physical Properties:

Property KP Value KN Value

Density (g/cm³) 8.5 8.6

Tensile Strength ≥490 MPa ≥390 MPa

Elongation ≥10% ≥15%

Thermocouples are used in processes to sense temperature and is connected to the pyrometers for indication and control. The thermocouple and pyrometer are electrically conducted by thermocouple extension cables / thermocouple compensating cables. The conductors used for these thermocouple cables are required to have similar thermo-electric (emf) properties as that of the thermocouple used for sensing the temperature.

Our plant mainly manufacture thermocouple wire, strip, and cable, and they are used in temperature measurement instruments. Our thermocouple products are all made abiding by GB and also IEC584-3 (International standard).

Thermocouple strip can be used to produce thermocouple connector's hollow pin, thermocouple spade, and thermocouple connector's contacts.

Application
• Heating – Gas burners for ovens
• Cooling – Freezers
• Engine protection – Temperatures and surface temperatures
• High temperature control – Iron casting