Teledyne HVC-282 instruction manual Calibration And Troubleshooting Guide, CheckingofTube, Page

5.0 CALIBRATION AND TROUBLESHOOTING GUIDE

AllHastingsVacuumGaugesandGaugeTubeshavebeencarefullycheckedandcalibratedatthefactorybeforeshipment. If acalibrationcheckisdesired,themethodsinthefollowingsectionsmayprovehelpful.

5.1 CheckingofTube:

Thesimplestandquickestmethodofcheckingoperationandcalibrationofagaugetubeistokeepanewsparecleangauge tubeonhandasa“standard”. Tocheckoperation,installbothnewandoldgaugetubestogetherinthesameclean,dry vacuumsystem,andpumpuntilasteadypressureisobtained. Plugthegaugeontobothtubesalternatelyandcheck readings. Iftheoldtubereadsahigherpressurethanthenewone,thisindicatesashiftintheoldtubewhichismost probablytheresultoftubecontamination. Calibrationcanpossiblyberestoredbygentlyswishingsolventsuchasacetone, orethylalcoholinthetubeend. Aftercleaning,thoroughlyairdrythetube. (Caution:Donotusehighpressureairjet,asthis willdamagethethermopileanddamagegaugetube.) Ifcalibrationcannotberestoredbythisprocedure,replacetheold tubewithanewgaugetube. Thetwotubescantrackoneanotherwithinclosetolerance,however,varianceofupto2xof accuracyspecificationstatedfortubemaybeseen,orcheckthegaugetubebymethoddescribedinSection5.2.

CAUTION: DonotattempttomeasuretheresistanceofthegaugetubeelementwithaDVMwhileitisunderhardvacuum unlessitsupplieslessthan350mVtoperformmeasurement,ormorethan929mVat15Torr,andnevermorethan1.5Vat ATMbetweenpins2(Black)and8(Red). Agoodtubewillreadaround25-30ohms. Ifopenordamaged,thermocouples willreadmuchhigher.

5.2 Calibration

AllHVC-282VacuumGaugeshavebeencarefullycheckedandcalibrated,alongwithDV-273GaugeTubeswhichare independentlymatchedforinterchangeability. Ifforsomereasonyouneedtocalibrateeithergaugeorgaugetube,please carefullyfollowcalibratinginstructionsbelow.

DV-273calibration. WedonotrecommendrecalibrationoftheDV-273gaugetubebecauseofequipmentrequirements,but wedoincludeasuitablemethodforyourreference. BestpossibleaccuracywillrequireaPrimaryStandardandpump systemwiththeabilityofpumpingdowntoatleast1mTorrorbetter. PleaserefertoFigure2.1.

NOTE: Forbestpossibleresults,temperaturechangesmustbeminimized,i.e.;handlingmustbeminimized. (SeeSec.3.2)

PleasereadSection3.2.

a)Apply 350mVDC ±50∝V to pins (+)8 & (-)2.

b)Pumpsystem/gaugetubedowntohardvacuum,<1mTorr.

c)UsingaDVMwitha200mVorbetterscale,connectedto(+)4&(-)6andadjustcenterpotin gaugetubeto0.000mV±5∝V.

d)Bringsystem/gaugetubeto15.000±1mTorr.

e)Increaseapplied350mVto929.85mV±50∝(V. CAUTION:Possiblegaugetubedamagewill result if at less than 15Torr.

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