To greater or lesser degrees, all electrical conducting materials have some amount of resistance to the flow of electricity. When a known electric voltage passes through a conductor, the resistance varies based on the temperature of the conductor. This resistance can be measured and will correspond to a specific temperature. While various elements are affected by temperature in different ways, platinum is commonly used in an RTD due to its purity, linearity and stability over a wide range of temperatures. An electronic readout device, such as a controller or digital indicator designed to measure resistance, is required for use with RTD sensors. Only two standard copper wires are necessary to connect an RTD to an electrical circuit, however, these connecting wires are also subject to small changes in resistance based on surrounding temperature. For this reason an “extra” third hookup wire is built into most RTDs as a compensation wire to allow the controller or display unit to correct for these variations.
Selecting a Temperature Sensor
Style
TIPTEMP RTD's are available in a variety of styles. The weather-proofed screw cover style provides an electrical conduit connection and can be used to house a transmitter (optional). For open system sensing, a nonthreaded style is offered. This design is provided with integrated leadwire and can be Teflon covered to protect the stem and leadwire against corrosive environments. A standard plug with a mating jack may also be furnished.
Stem (Sheath)
All TIPTEMP RTDs are furnished with a 316 stainless steel stem, with the internal wiring packed in powdered ceramic. The screw head cover style is available in two stem types: welded and spring loaded. The welded stem is suitable for use in liquid applications. The spring loaded stem is designed to bottom out inside a thermowell, providing maximum heat sensitivity. Spring loaded stems are not pressure tight and may allow process media to escape; therefore, they must always be installed in a thermowell.
Insertion (U) Length
The insertion (U) length of an RTD represents its depth into the process vessel or thermowell. TIPTEMP RTDs are available in standard U-lengths from 2" to 24". Other lengths are available upon special order, please consult factory.
Measuring (Hot) Junction
TIPTEMP RTDs are a platinum, 3-wire design, and are furnished with either 100Ω or 1000Ω resistance at 32°F (0°C), and a temperature coefficient of 0.00385 Ω/Ω/°C.
Connection (Termination)
TIPTEMP RTDs are provided with a terminal block (screw cover head) or integrated leadwire connection. The terminal block connection has no leadwire, therefore extension wire must be attached and routed to the indicator or controller.
Temperature Tools Catalog
Below are pages from our Red "Temperature Tools" Catalog. These pages will enable you to construct a part number for your particular sensor. When you have your part number call 1-800-847-8367 to get a price.
