Farr HD8625 - Torque Measurement; A. BASIC TORQUE MEASUREMENT

Technical Manual
hD8625 8-
5
/
8
” 35K Tong
6.1
Torque MeasureMenT
A. BASIC TORQUE MEASUREMENT
Basictorquemeasurementsareperformedusingasimplehydraulicmeasurementsystem.Ahydraulicloadcellconnectstoacalibrated
torquegaugethroughareinforcedflexiblehydraulichose.Thetorquegaugeisfactory-calibratedtodisplayaccuratetorquemeasurements
foratongortongandbackupassemblywithaparticulararmlength.Thearmlengthisameasurementfromthecentreofthepipeorcas-
ingtothecentreoftheforcebeingappliedtotheloadcell.
Twoloadcelloptionsareavailable.Atensionloadcellistypicallyusedwithasuspendedstand-alonetong.Thisapplicationrequiresthat
theloadcellbeattachedtotherearofthetongaspartoftherestraintlinethatopposestheforcegeneratedwhenthetongmakesup
orbreaksoutajoint.Acompressionloadcellisusedinatongandbackupassembly,andistypicallylocatedontherearofthebackup
betweenthebackupandastationaryframe.Theloadcellmustbelocatedinthecentreofthecompressionforcevectorgeneratedbetween
thebackupandtheframe.
Hydraulicforcegeneratedbyaloadcellistransmittedtothetorquegaugeviaareinforcedflexiblehydraulicline.Thehydraulicforceis
displayedastorqueinunitsofFt.-Lbs.Thetorquegaugehasared“peaktorque”indicatorthattrackswiththetorquegaugeneedleto
thepointofhighesttorque,andremainsatthepointofhighesttorqueuntilmanuallyreset.Notethateverymodeloftongandtongand
backup assembly has a uniquearm length, and thetorque gauge must becalibrated for that arm length.Torquegaugesthatare not
calibratedforthearmlengthofthetoolinservicewillnotdisplaycorrecttorque.Toensurecorrecttorquemeasurement,ensurethearm
lengthor“handle”asdisplayedonyourtorquegaugematchesthearmlengthofthetoolinserviceaslistedonthespecificationspageof
thetechnicalmanual.
Theimagesonthispageareforillustrationpurposesonlyandmaynotaccuratelyrepresentthetorquegaugeandloadcellthathavebeen
suppliedwithyourequipment.
IllustratIon 6.a.1: torque gauge (for
IllustratIon PurPoses only)
IllustratIon 6.a.2: tensIon loaD Cell
IllustratIon 6.a.3: ComPressIon loaD Cell
THE IMAGES DISPLAYED ARE SUPPLIED FOR ILLUSTRATION PURPOSES ONLY
TORQUE GAUGES AND LOAD CELLS ARE FACTORY-SUPPLIED SUPPLIED AS MATCHED CALI-
BRATED PAIRS. IF REPLACING EITHER COMPONENT THE LOAD CELL AND TORQUE GAUGE
MUST BE RETURNED TO THE FACTORY FOR RE-CALIBRATION BEFORE PLACED INTO SERVICE.
Torquegaugesandloadcellsaresuppliedasamatchedcalibratedpair.Substitutingoneortheotherwillrenderthecalibrationinaccurate
eveniftheactualmodelnumbersappeartobeidentical.Theserialnumbersofmatchingloadcellandtorquegaugesareclearlyidentified
onthecalibrationcertificate.Shouldyoususpecttheaccuracyofyourtorquemeasurements,orwishtoreplaceeithercomponentthepair
shouldbereturnedtothefactoryforre-calibrationbeforeplacingintoservice.