Distinguishing between genuine and counterfeit platinum-rhodium alloy thermocouple wire requires a comprehensive assessment through label verification, composition analysis, density measurement, resistance and thermoelectric potential testing, and high-temperature stability verification. This helps avoid temperature control inaccuracies or equipment damage caused by using counterfeit products.
1. Verify Brand Labels and Certification Documents (Initial Screening)
Check if the wire or packaging is labeled with the model number (e.g., S-type, B-type), brand logo, batch number, and IEC 60584 Grade 1 standard number.
Genuine products come with a factory inspection report, a traceable QR code, or a calibration certificate.
High-end brands (such as Omega and TECO) laser-engraved batch numbers on the wire itself, which can be verified through their official websites.
Tip: Counterfeit products often lack complete labeling, or the font is blurry or the information is incomplete.
2. Chemical Composition Analysis (Core Method) X-ray fluorescence spectrometry (XRF) or inductively coupled plasma mass spectrometry (ICP-MS) is used for detection:
Platinum (Pt) content >70%, rhodium (Rh) content between 6% and 30% (depending on the model);
If a large amount of nickel (Ni), chromium (Cr), or iron (Fe) is detected, it is a K/N type base metal masquerading.
Acceptance Standard: Rh content deviation ≤ ±0.1%, ensuring stable thermoelectric performance.
Recommendation: All new batches must be inspected; establish a composition database for comparison.
3. Density and Tactile Identification (Auxiliary Method)
Platinum has a density of 21.45 g/cm³, much higher than nickel (8.9 g/cm³);
For the same volume, platinum-rhodium alloy wire is significantly heavier, feeling "deep" in the hand;
The density can be verified by measuring the mass per unit length using a precision balance and calculating the density based on the diameter.
Note: This method applies to whole bare wires, not to counterfeit wrapped products.
4. Resistance and Thermoelectric Potential Characteristics Testing
Cold Resistance Measurement: Platinum-rhodium alloy has lower resistance per unit length (approximately 10–15 Ω/km); Type K is approximately 40 Ω/km, significantly higher.
Thermoelectric Potential Output Test: At 600℃, Type S outputs approximately 5.891 mV, and Type B approximately 5.019 mV; Measure using a standard heat source (such as a dry well furnace) and compare with IEC 60584 standard values.
Practical Tip: Heat the wire under test in parallel with a known Type S standard part and observe whether the temperature difference displayed by the temperature control system is >1℃.
5. High-Temperature Stability Observation (Long-Term Verification)
After 100 hours of continuous operation at temperatures above 1300℃: Genuine product exhibits a thermoelectric potential drift of <2μV (approximately 1.3℃), demonstrating excellent stability; Counterfeit products, due to impure materials, often show a drift exceeding 5μV, and may even break.
Observe the surface condition after use: Platinum-rhodium alloy shows no obvious oxidation or discoloration, while nickel-chromium alloy is prone to blackening and peeling.
Recommended Operation: The use of unbranded, untested "white-label" wire is prohibited in critical workstations.
