It is a PT 100 Ω device and can measure the -200 ~ 300 ℃. by applying a circular connectors It is easy to remove and attach
Protection tube material : SUS316 OR SUS304 Diameter of protection tube : 3.2Φ OR OTHER length of protection tube : 50~1000mm Connection Screw : PT1/2 OR OTHER JIS CLASS A
Product Specification / Models
They, in the case of Platinum known variously as PRTs and PRT100s, are the most popular RTD type, nearly linear over a wide range of temperatures and some small enough to have response times of a fraction of a second. They are among the most precise temperature sensors available with resolution and measurement uncertainties or ±0.1 °C or better possible in special decisions.
Usually they are provided encapsulated in probes for temperature sensing and measurement with an external indicator, controller or transmitter, or enclosed inside other devices where they measure temperature as a part of the device's function, such as a temperature controller or precision thermostat.
This product is available for the overall sector automotive, steel, pharmaceutical, shipbuilding, chemical, etc.
The Advantages of RTDs
The advantages of RTDs include stable output for long period of time, ease of recalibration and accurate readings over relatively narrow temperature spans. Their disadvantages, compared to the thermocouples, are: smaller overall temperature range, higher initial cost and less rugged in high vibration environments.
They are active devices requiring an electrical current to produce a voltage drop across the sensor that can be then measured by a calibrated read-out device.
RTD Error Sources
The lead wires used to connect the RTD to a readout can contribute to their measurement error, especially when there are long lead lengths involved, as often happens in remote temperature measurement locations. Those calculations are straight forward and there exist 3-wire and 4-wire designs to help minimize or limit such errors, when needed.
Often the lead error can be minimized through use of a temperature transmitter mounted close to the RTD. Transmitters convert the resistance measurement to an analog current or serial digital signal that can be sent long distances by wire or rf to a data acquisition or control system and/or indicator.
RTDs, as mentioned above, work in a relatively small temperature domain, compared to thermocouples, typically from about -200 °C to a practical maximum of about 650 to 700 °C. Some makers claim wider ranges and some construction designs are limited to only a small portion of the usual range.
Insulation resistance is always a function of temperature and at relatively high temperature the shunt resistance of the insulator introduces errors into measurement. Again, error estimates are straight forward, provided one has a good estimate of the thermal properties of the insulator.
Insulator material such as powdered magnesia (MgO), alumina (Al2O3) and similar compounds are carefully dried and sealed when encapsulated in probes along with an RTD element.
ASTM has standards related to insulation resistance testing to help determine the performance of such sealed probes, specifically E 1652-00.
RTDs Other Than Platinum
RTDs can be made cheaply in Copper and Nickel, but the latter have restricted ranges because of non-linearities and wire oxidation problems in the case of Copper.
Platinum is the preferred material for precision measurement because in its pure form the Temperature Coefficient of Resistance is nearly linear; enough so that temperature measurements with precision of ±0.1 °C can be readily achieved with moderately priced devices. Better resolution is possible, but equipment costs escalate rapidly at smaller error levels.
Standard Platinum RTDs(SPRTs)
The ITS-90 (International Temperature Scale of 1990- used as a worldwide practical temperature scale in national metrology labs like NIST, NPL et al) is made up of a number of fixed reference points with various interpolating devices used to define the scale between points. A special set of PRTs, called SPRTs, are used to perform the interpolation in such labs over the ranges 13.8033 K (Triple point of Equilibrium Hydrogen) to the Freezing point of Silver, 971.78 °C.
The Hart Scientific website provides a glimpse into the realm of precision SPRTs and readout equipment used in calibration labs. They operate one of the very few labs in the USA with accreditation under NVLAP to the ISO/IEC 17025 standard
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