
BRONKHORST HIGH-TECH B.V.
9.17.057 page 9
2.9 Purging
Insystemsforusewithcorrosiveorreactivefluids,purging foratleast30minuteswithadry,inertgas
(likeNitrogenorArgon)isabsolutelynecessarybefore use.Afterusewithcorrosiveorreactivefluids,
completepurgingisalsorequiredbeforeexposingthesystemtoair.
Warm‐uptime:
Lettheinstrumentswarm‐upforatleast30minutesforbestaccuracy.
Duringwarm‐upperiod,fluidpressuremayeitherbeonoroff.
2.10 Zeroing
Thezero‐pointofeachinstrumentisfactoryadjusted.Ifsorequiredthezeropointmaybere‐
adjustedoverRS232orfieldbusorbymeansofusingthemicroswitch.Procedureforzeroing by
microswitch:
Warm‐up,pressureupthesystemandfilltheinstrumentaccordingto theprocess
conditions.
Makesurenoflowisgoingthroughtheinstrumentbyclosingvalvesneartheinstrument.
Thesetpointmustbezero.
Pressmicroswitchandholdit.AfterashorttimetheredLEDwillgoONandOFF,thenthe
greenLEDwillgoON.Atthatmomentreleasethemicroswitch.
ThezeroingprocedurewillstartatthatmomentandthegreenLED willblinkfast.The
zeroingprocedurewaitsforastablesignalandsavesthezero.Ifthesignalisnotstable,
zeroingwilltakelongandthenearestpointtozeroisaccepted.Theprocedurewilltake
approx.10seconds.
Whentheindicationisshowing0%signalandthegreenindicationLEDisburningcontinuouslyagain,
thenthezeroingactionwassuccessful.
2.11 Calibration
EachFLOW‐SMSinstrumentisfactorycalibrated.Calibrationcertificatesareincludedintheshipment.Whenoperated
properly(cleangases,nopressureshocks,novibrations,nothermalshocks,etc),regularmaintenanceisnotrequired.
However,periodicalinspection,recalibrationorverificationoftheaccuracymaybesubjecttoindividualrequirements
oftheend‐user.Pleaserefertotheinternaloperationalrequirementsofyourcompany.
2.12 Supply pressure
Itisrecommendedtoturnonpowerbeforeapplying pressureontheinstrumentandtoswitchoff
powerafterremovingpressure.
Turnonfluidsupplygently.Avoidpressureshocksandbringtheinstrumentgraduallyuptothelevelof
theactualoperatingconditions.Alsoswitchofffluidsupplygently.
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