![]() To select the optimal temperature measurement device for your application, you must first have an understanding of the differences between Thermocouple, RTDs and Thermistors. A thermocouple generates a voltage that is more or less proportional to the difference in temperature between the junctions. Using fiber optic cables, they can measure surfaces that are not within a direct line of sight. However, they are generally not as accurate and are sensitive to surface radiation efficiency (or more precisely, surface emissivity). Infrared Sensors can be used to measure temperatures higher than any of the other devices and do so without direct contact with the surfaces being measured. K Type CJMCU-96 MCP9600 Thermocouple Converter Module Differential Input Condition: New Bulk savings: 38.22/ea 37.46/ea 37.07/ea 4 or more for 36.31/ea Quantity: More than 10 available Price: US 38.22/ea Buy It Now Add to cart Best Offer: Make offer Add to Watchlist Free returns Shipping: US 3.50SpeedPAK Standard. Thermistors tend to be more accurate than RTD's or thermocouples, but they have a much more limited temperature range. Since they require the use of electric current to make measurements, RTD's are subject to inaccuracies from self-heating. optional: software-based conversion of the voltage into a temperature value according to the set thermocouple type (K, J, ) All three steps can take place. RTD's are stable and have a fairly wide temperature range, but are not as rugged and inexpensive as thermocouples. Using the Seebeck effect (explained above), a thermocouple generates a voltage according to the temperature difference T between the junction of the two types. Another issue is that all thermocouple tables are referenced to the cold end being at 0C. ![]() In addition, Thermocouples generally can measure temperatures over wide temperature ranges, inexpensively, and are very rugged, but they are not as accurate or stable as RTD's and thermistors. Monograph 175 Revised to ITS-90 Revised Thermocouple MAXIMUM TEMPERATURE RANGE Reference Tables Thermocouple Grade 200 to 1250C, 328 to 2282F Extension Grade 0 to 200C, 32 to 392F LIMITS OF ERROR (whichever is greater) Standard: 2.2C or 0.75 Above 0C 2.2C or 2.0 Below 0C Special: 1.1C. The voltage that a thermocouple makes is non-linear, so the voltage from 100C to 120C is different than 0C to 20C and you have to account for that to get an accurate MEASUREMENT. You have to consider the characteristics and costs of the various sensors as well as the available instrumentation. ![]()
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