We must solve these problems satisfactorily to provide a proper calibration. Often, the required immersion is not stated or specified. The most common type (PT100) has a resistance of 100 ohms at 0 °C and 138.4 ohms at 100 °C. Extensive Range of Platinum Resistance Thermometer (RTD's) A platinum RTD (Resistance Temperature Detector) with a resistance of 100 ohms at 0°C which changes with temperature. These include helium vapor pressure thermometers, helium gas thermometers, standard platinum resistance thermometers (known as SPRTs, PRTs or Platinum … Platinum is usually used due to its stability with temperature. Therefore, we must understand the requirements to an extent that allows us to adapt our process, if necessary, to accommodate a new or unusual configuration. The resistance of the metal is directly proportional to the temperature. The platinum sensing resistor is highly stable and allows high accuracy temperature sensing. As mentioned, PRTs are available in many configurations, however PRTs which are suitable for use as calibration standards are generally available as 100W stainless steel sheathed probes. In the range -200°C ≤ ϑ < 0°C electrical resistance at temperature tis calculated according to the polynomial: In the range of 0°C ≤ ϑ ≤ 850°C coefficient cis set to zero and the polynomial becomes: For conversion of electrical resistance to temperature the above equations can be used after solving for t: Polynomial coefficients for conversion of resistance to temperature, or vice versa, from platinum resistance thermometers according to IPTS-6… Calibration uncertainties range from 0.010°C to 0.025°C. Some calibration baths have fluid level adapters which actually raise the fluid up to the top of the bath lid. When accuracy requirements are less severe, PRTs can be used successfully. Details. Common RTD sensing elements constructed of platinum, copper or nickel have a repeatable resistance versus temperature relationship (R vs T) and operating temperature range. Standard platinum resistance thermometers (PRTs) are very high accuracy instruments which are sensitive to electrical noise and their thermal treatment is crucial. Whatever type of temperature source is used, the most important consideration is the application itself. δ = constant δ lies between 1.488 to 1.498. ), then certainly it can be used for both. Be careful in the selection of a PRT to ensure that the type selected is appropriate for use as a calibration reference over the range of interest and with the required accuracy. SPRTs (Standard Platinum Resistance Thermometers) are the most accurate and stable instruments available for this purpose. As PRT’s are not completely linear polynomial approximation is required. These instruments are highly stable and accurate, but they are expensive and extremely delicate. Platinum Resistance Thermometers (Pt100, Pt1000, RTD) ... No special extension cables or cold junction compensations are required The resistance of a conductor is related to its temperature. Dry-wells are used in applications where probe consistency (diameter and length) is present and modest accuracy is desired. Many modern thermometer readouts are designed to cover this span on a single range. Some of these characteristics are: The list above shows that PRTs are suitable for use over a wide temperature range. Calibration of short UUTs presents many problems with regard to the temperature source. Standard platinum resistance thermometer model CTP5000-T25 Applications Reference thermometer for very accurate temperature measurements in a range of -189 … +660 °C Precision standard platinum resistance thermometer (SPRT) designed to realise the international temperature When calibrating PRTs against a reference PRT or SPRT, the technical requirements for the readout are the same for the UUTs and the reference. Although the basic calibration requirements are the same, these various configurations pose different problems in the laboratory. These instruments are not as accurate as SPRTs but they are generally more rugged and easier to work with. The current international standard which specifies tolerance, and the temperature-to-electrical resistance relationship for platinum resistance thermometers is IEC 751:1983. Our UKAS temperature laboratory uses a range of reference platinum resistance thermometers, noble metal thermocouples, stirred liquid baths, specially designed isothermal calibration furnaces and black body sources to provide a comprehensive facility for cost effective thermometer calibration or temperature probe calibration over the range -80ºC to 1,200ºC. How to Calibrate an RTD or Platinum Resistance Thermometer (PRT) (App Note), How to do a temperature sensor comparison calibration (Blog), Annealing a PRT: Why, When and How (Webinar), Speak with a calibration product expert about your probe and equipment needs. Too much source current will result in excessive self-heating and incorrect calibration. Additionally, unlike SPRTs, the design of PRTs is left to the discretion and ingenuity of the manufacturer. ĞÏࡱá > şÿ 1 3 şÿÿÿ 0 ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿì¥Á 7 ğ¿ : bjbjUU “ 7| 7| ¹ ÿÿ ÿÿ ÿÿ l ´ ´ ´ ´ L L L ` ` ,' ¶ : : : : : ½# ½# ½# Ÿ&. Even an excellent instrument may not perform adequately in a specific application if it is not matched to that application. They are the instruments specified in the International Temperature Scale of 1990 (the ITS-90) for performing measurements within the range -259.3467 °C (the triple point of hydrogen) to 961.78 °C (the freezing point of silver). Standard Platinum Resistance Thermometers (SPRTs) are used to interpolate temperature in the range from -189.3442°C to 660.323°C on the International Temperature Scale of 1990 (ITS-90). PRTs, like any probe, have immersion requirements which vary from configuration to configuration. Definition: The platinum thermal resistance (PTR) uses platinum for determining the temperature. For commercially produced platinum resistance thermometers, standard tables of resistance versus temperature have been produced based on an R value of 100 ohms at 0°C and a fundamental interval (R 100 - R 0) of 38.5 ohms (α coefficient of 3.85x10-3 /°C) using pure platinum doped with another metal (see Part 2, Section 6). PT-100 platinum resistance thermometers (PRTs) are an excellent choice for use as cryogenic temperature sensing and control elements in the range from 30 K to 873 K (-243 °C to 600 °C). Within the above the temperature zone, it is also used directly for measuring the temperature of high-accuracy. In some cases, particularly with older DMMs, the source current is so high that damage to the sensor is likely. A platinum resistance thermometer (PRT) is a thermometer constructed from a high purity platinum element (wire-wound coil or thin film) placed in a tube of metal or glass and sealed with an inert atmosphere and/or mineral insulator. Ensure that the readout is using the proper source current. They are generally available in 0.25, 2.5, 25, and 100W versions with either borosilicate glass (Pyrex), fused silica glass (quartz), stainless steel, or INCONEL sheath materials. The two most important considerations are uniformity and stability. Before selecting a readout, review the information presented in the readouts section with regard to current settings, timing, multiplexing, etc. The number of calibration points depends on the range and accuracy desired but, because the temperature response of platinum is relatively linear and very well known, fewer calibration points are required for a given range compared to other sensor types. This will result in inconsistent self-heating and additional calibration errors. I. If you purchased an item from a Fluke authorized distributor, please contact them directly with questions regarding Certificates of Calibration or other documentation. Since the early days of resistance thermometry and the work of Callender on the platinum resistance thermometer, the subject of resistance thermometry has undergone considerable changes. Temperature ranges can be measured between approximately 1,300 to 5,800oF (700 to 3,200oC), and with appropriate filters, the disappearing-filament pyrometer temperature ranges can be ex-tended to approximately 18,000oF (10,000oC). Standard Platinum Resistance Thermometers (SPRTs), Standard Platinum Resistance Thermometers, Automated Pressure Controller / Calibrators, Pneumatic Pressure Controllers / Calibrators, High Pressure Pneumatic Controller / Calibrators, High-Pressure Hydraulic Deadweight Testers, Mechanical / Dimensional Calibration Software, Thermocouple Voltage to Temperature Calculator, DH Instruments Pressure and Flow Calibration, Wide temperature Range (–260°C to 1000°C), Electrical resistance is typically between 0W and 400W and depends on temperature, Shallow slope (i.e. Platinum is the most reliable metal due to its linear resistance to temperature relationship over a large temperature range. 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