RTD Temperature Sensor Data Sheet DS33-200-6

1 DescriptionThe RTD Temperature Sensor is thelatest development for measuringthe Temperature of materials pro-cessed in glassed-steel reactors. Itis a three-wire, 100 ohm platinumResistance Temperature Detectorpermanently encased in a corro-sion resistant tantalum RTD operates on the princi-ple that the electrical resistanceof a platinum wire increases withits Temperature in a precise andrepeatable manner. The relation-ship between the temperatureand the resistance of a knownpurity of platinum is defined by a specific ResponseAn important characteristic of theRTD is its immediate response torapid Temperature changesthroughout its entire operatingrange.

2 This characteristic is maxi-mized by the design of the sen-sor in the reactor vessel. Theaccompanying time-temperaturegraph illustrates the response ofthe RTD in a step Temperature change test. As shown, the firsttime constant of an RTD installedon a Glasteel accessory is is of significance in themeasurement of Temperature withinreaction vessels, particularly whenthe measurement is the basis forcontrol action. The nominal accu-racy of the RTD is C ( F)or of the Temperature beingmeasured, whichever is Table 1. The use of three wirespermits compensation for leadwire resistance . Therefore, the length of the lead wires between the RTD andthe instrument does not affectthe SensitivityThe RTD has a high sensitivity tosmall Temperature changes whichis vital to precise temperaturemeasurement and control withinvery narrow limits.

3 The outputsensitivity is approximately tentimes greater than thermocouplesused in the same type of applica-tions. The RTD eliminates theneed for high-gain amplifiers andreduces susceptibility to electron-ic noise characteristic of systemswhich depend on low-magnitudesensor Output SignalFor reliable control applications,sensors must be free of indicate the RTDshave a drift no greater than C ( F) in one year. RTD Temperature SensorData Sheet DS33-200-6 The Temperature of very low liquidlevels can be measured accuratelywith a flush valve mounted RTDT emperature 1 resistance of RTD(ohms) Temperature CTemperature ( ) ( ) ( ) ( ) ( ) ( )-20 ( )2032 ( )60100 ( )140180212 ( )220260300( )340380420450 ( )Nominal resistance - Temperature Values RTD Temperature Sensor Basis: ohms at 0 C (32 F)Temp 2/13/98 1:04 PM Page 2 SystemABC% of True Liquid Temperature until the vessel isdrained.

4 There is virtually no liquidlevel at which Temperature cannotbe following options are availableon a built-to-order basis: European Standard temperaturecoefficient per DIN 43760. Two independent RTD elements installed within thesame enclosure. Enclosure material other thantantalum. Thermocouples Type J and LocationsThe RTD is factory installed withwires and terminal head on suchGlasteel accessories as flushvalves, baffles and can be purchased sepa-rately for field installation on baf-fles and thermowells providedthe accessory has a removablerestricted tip and is drilled andtapped to the proper at Very LowLiquid LevelsThe RTD mounted in a flush valve(as illustrated) solves the problemof measuring temperatures whenthe level of the process liquid inthe reaction vessel is extremelylow.

5 When the liquid drops belowthe minimum level required bysensors mounted on the end ofbaffles or thermowells, the valve-mounted RTD continues to pro-vide dependable temperatureData Sheet DS33-200-6 Comparative Response TimeNOTE: Data intended for com-parison. Not for guarantee (F )100 F - 200 F TRUE LIQUID STEP Temperature CHANGE2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 SYSTEMA:PFAUDLERRTDTEMPERATURESENSORSYST EMC:GAS-FILLEDBULBINGLASTEELTHERMOWELLSY STEMB:GAS-FILLEDBULBINTANTALUM-COATEDTHE RMOWELL 1ST TIME CONSTANTS peed of ResponseControl reliability is further assuredby the conformance of each RTDto a repeatability specification of C ( F) over the -29 Cto +232 C (-20 F to +450 F)operating provide a nearly linear outputthus minimizing any loss of accu-racy when the output passesthrough a transmitter.

6 This linearityextends over the entire recom-mended Temperature it requires an externalpower source, the RTD is a non-inductive design which cannot storeenergy. When used with instrumen-tation systems approved by FactoryMutual Research Corporation asintrinsically safe, and with specifiedbarriers, the RTD is consideredintrinsically safe in hazardous 2/13/98 1:04 PM Page 3 resistance at 0 C (32 F) Coefficient:American Standard Range:-29 C to +232 C (-20 F to +450 F).Lead Wires:Two white and one red. PTFE coated, overwrapped with PTFE tape into a single Sheet DS33-200-6 }In addition to flush valves, RTDscan also be supplied on baffles(as shown) and Temperature SensorStandard Design SpecificationsFlush ValveBaffleThread Sizes:5/16 - 24, for flush - 18, for flat surfaces (baffleor thermowell factory drilled andtapped).

7 1-1/8 - 12 for flat surfaces (baf-fle or thermowell factory drilledor tapped).Enclosure Material:TantalumSensorTerminal headSensorTerminal headLead wiresHeat transfer epoxyAluminum oxideencapsulationCeramic coreTantalum casePlatinum resistance wireTemp 2/13/98 1:04 PM Page 42/98 EPI 1M Mech No. 37 Data Sheet DS33-200-6 The information contained in this bulletin isbelieved to be reliable general guidelines forconsideration of the products and servicesdescribed herein. The information is general innature and should not be considered applicableto any specific process or application. Pfaudler,Inc.

8 And Glasteel Parts and Services expresslydisclaim any warranty, expressed or implied, offitness for any specific purpose in connectionwith the information contained Saginaw DrivePO Box 20857 Rochester, NY 14602 Phone: 716 235 1010 Fax: 716 235 7923 Copyright Pfaudler, Inc. 1998 A Unit of Robbins & Myers, Inc. All rights is a registered trademark of Pfaudler, West AvenuePO Box 23600 Rochester, NY 14692-3600 Phone: 716 235 1000 Fax: 716 423 2/13/98 1:03 PM Page 1