ST100 Series Flow Meter APPENDIX D - GLOSSARYFluid Components International LLC 85APPENDIX D GLOSSARYAbbreviationsDelta-R (DR) Differential ResistanceDelta-T (DT) Differential TemperatureDMM Digital MultimeterDPDT Double Pole Double ThrowFCI Fluid Components IntlHTR HeaterLED Light Emitting DiodePOT PotentiometerRA Return AuthorizationRTD Resistance Temperature DetectorSFPS Standard Feet Per SecondSPDT Single Pole Double ThrowDefinitionsActive RTD The sensing element that is heated by the heater. The active RTD is cooled due to increases in the processfluid flow rate or density (level sensing).Differential resistanceDelta-R (DR) The difference in resistance between the active and reference RTDs.Differential temperatureDelta-T (DT) The difference in temperature between the active and reference RTDs.Heater (HTR) The part of the sensing element that heats the active RTD.Local enclosure The enclosure attached to the sensing element. (Usually contains the control circuit and mounting socket.)Reference RTD The part of the sensing element that senses the process media temperature.Remote enclosure An optional protective enclosure for the control circuit. Used when the control circuit must be located awayfrom the sensing element.Resistance TemperatureDetector (RTD) A sensor whose resistance changes proportionally to temperature changes.Sensing element The transducer portion of the instrument. The sensing element produces an electrical signal that is related tothe flow rate, density (level sensing), and temperature of the process media.Thermowell The part of the sensing element that protects the heater and RTDs from the process fluid.Turndown The ratio of the upper to lower flow rate values.
