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Control and Instrumentation GlossaryWe have 15 entries in our Glossary for this letter. Radio Frequency The frequency range between ultrasonic and infrared. Further Reading RAL Number The RAL catalogue is an international color standard that defines colours according to numbers and names e.g. RAL7032 is a flinty grey colour. Further Reading Range The region between the limits within which a quantity is measured; received or transmitted expressed by stating lower and upper range values. Further Reading Redundancy The existence of more than one piece of equipment any of which could perform a given function. These multiple pieces of equipment are used to help improve the reliability and availability of the system. Further Reading Repeatability A quantitive measure of the variability associated in obtaining succesive repeat results from the same instrument in the same location under similar conditions. Further Reading Reproducibility The closeness of agreement among repeated measurements of an output for the same value of input made under the same operating conditions over a period of time. Further Reading Resolution The smallest change in input which produces a detectable change in output i.e. the smallest increment of change that can be detected by a measurement system. Further Reading Resonance A condition of oscillation caused when a small amplitude of periodic input has a frequency approaching one of the natural frequencies of the driven system. Further Reading Response Time An output expressed as a function of time. Common to use T90, i.e. time to achieve 90% of output. Further Reading RF Raised Face Description of the mating face of a flange. Further Reading RFI - Radio Frequency Interference Noise induced upon signal wires by ambient radio-frequency electromagnetic radiation with the effect of obscuring an instrument signal. Further Reading RH - Relative Humidity An expression of the level of water vapour present compared to the maximum amount of water vapour that a gas could carry at that temperature. It is expressed in percentage terms. Further Reading RTD - Resistance Temperature Detector Resistance Temperature Detectors (RTD's) provide temperature measurement through changes in electrical resistance. Further Reading RTJ - Ring Type Joint Description of the mating face of a flange where the mating face has a machined groove into which the gasket is inserted. Further Reading RTU Remote Telemetry Unit Further Reading |
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