B44 Temperature Sensors Building Automation Products, Inc. • 750 North Royal Avenue, Gays Mills, WI 54631 USA Tel: +1-608-735-4800 • Fax: +1-608-735-4804 • Email: sales@bapihvac.com • Web: www.bapihvac.com Features & Options ● ThreeLengths:2”,4”and8” (FitstandardImmersionUnitlengths) ● StainlessSteel(304or316)orBrass ● OtherLengthsAvailableUponRequest ● LimitedLifetimeWarranty StandardThermowellsavailablefromBAPIincludemachined304stainlesssteel,316stainless steel,brass.Thesewellsareofferedin2”,4”and8”lengthswith1/2”NPTexternaland1/2” NPSMinternal.Otherlengthsandthreaddiametersareavailableuponrequest. TheThermowellchosenforaninstallationisgovernedmainlybythecorrosionconditions thewellwillface.Themachinedstainlesssteelwellsallcomewithamirrorpolishtoprovide maximumcorrosionresistance. Occasionally,thematerialconsiderationisoneofstrengthratherthancorrosion.Forexample,a machinedstainlesssteelwellmayberequiredforhighpressurewaterservicewhereotherwise abrassthermowellwouldbesatisfactoryfromacorrosionstandpoint. Machined Thermowell Thermowells Specifications NPT= National Pipe Taper NPSM=National Pipe Straight Mechanical (not tapered) Rev.09/20/22B45 Temperature Sensors Building Automation Products, Inc. • 750 North Royal Avenue, Gays Mills, WI 54631 USA Tel: +1-608-735-4800 • Fax: +1-608-735-4804 • Email: sales@bapihvac.com • Web: www.bapihvac.com Gray shaded items follow the Buy and Resale Multiplier. Thermowells Part #Description BA/2”M304...................Machined 304 Stainless Steel - 2” BA/4”M304...................Machined 304 Stainless Steel - 4” BA/8”M304...................Machined 304 Stainless Steel - 8” BA/2”M316...................Machined 316 Stainless Steel - 2” BA/4”M316...................Machined 316 Stainless Steel - 4” BA/8”M316...................Machined 316 Stainless Steel - 8” BA/2”MB ......................Machined Brass - 2” BA/4”MB ......................Machined Brass - 4” BA/8”MB ......................Machined Brass - 8” Note:Standardthreadsizeis½”NPTexternal,and½”NPSMinternal.2”unitshaveaninsertion lengthof2.5”(5.1cm).4”unitshaveaninsertionlengthof4.5”(11.43cm).8”unitshaveaninsertion lengthof7.5”(19.05cm). Ordering Information Thermowellfailures,inmostcases,arenotduetotheeffectsofpressureortemperatureonthe thermowell.Thecalculationsnecessarytoprovideadequatestrength,undergivenconditions,are familiarenoughtopermitproperchoiceofwallthicknessandmaterial.ThevaluesshowninTable1are conservative,andintendedprimarilyasaguide. Lessfamiliar,andmoredangerous,arethe vibration effectstowhichthermowellsaresubjected.Fluid, flowingbythethermowell,formsaturbulentwake(calledtheVonKarmanTrail)whichhasadefinite frequency,basedonthediameterofthethermowellandthevelocityofthefluid.Itisimportantthatthe thermowellhavesufficientstiffnesssothatthewakefrequencywillneverequaltheresonant(natural) frequencyofthethermowellitself.Iftheresonantfrequencyofthethermowellcoincidedwiththewake frequency,thethermowellwouldvibratetodestructionandbreakoffinthepiping.Thermowellsarealso safeiftheresonantfrequencyisthermowell belowthewakefrequencyorifthefluidvelocityisconstantly fluctuatingthroughthecriticalvelocitypoint. Nevertheless,iftheinstallationisnothamperedbytheuseofasufficientlystiffthermowell,we recommendthevaluesgiveninTable2notbeexceeded. Comparing the Wake Frequency and the Resonant Frequency Table 1: Pressure Rating versus Temperature Table 2: Maximum Fluid Velocity versus Insertion Length ThevaluesshowninTable2are basedonoperatingtemperaturesof 350°Fforbrassand1,000°Ffor304 and316stainlesssteel(S.S.).Slightly highervelocitiesarepossibleatlower temperatures.Next >