Brookfield PFT Powder Flow Tester - I. INTRODUCTION

AMETEK Brookeld Page 5 Manual No. M09-1200-F1016
I. INTRODUCTION
Thereisaneedthroughoutindustrytocharacterizepowderowpropertiesandowbehavior.
TheBrookeldPowderFlowTester(PFT)isaprecisioninstrumentofrobustdesignthatsatises
thisneedandcanbeusedtomeasure,displayandprintoutowresultsatspeciedcompaction
loads. Potential users include R&D Departments, QC laboratories, Incoming Inspection for raw
materials, and government/university organizations.
The principal of operation of the PFT is to drive a compression lid vertically downward into a
powdersamplecontainedinanannularshearcell.Thepowdersamplehasadenedvolume
and the weight of the sample is measured before the start of the test. A calibrated beam load
cell is used to control the compaction stress applied to the powder. The annular shear cell is
thenrotatedatadenedspeedandthetorqueresistanceofthepowderintheshearcellmoving
againstthepowderinthestationarylidismeasuredbyacalibratedreactiontorquesensor.The
geometries of the lid, shear cell, rotational speed of the cell, and the compressive loads applied
tothepowderallcontributetothecalculationswhichdeterminethe“owability”ofthepowder.
The intended uses for the PFT include:
• Pass/failteststocertifymaterialqualitypriortoshipment
• Providingmeaningfulnumbersthatguidehowpowderwillowinsilos,hoppers,feeders,
llingmachinesandsimilarequipment
• Benchmarkingfordailyproductionlotsorforcomparingowbehaviorofnew
formulations against existing product
• Creating databases for choice of production lines, sourcing, formulation and second source
suppliers
• Producingquantitativeresultsthatcanbeusedfordesignofprocessingplantsand
equipment
ThereareseveralpowderowpropertieswhichthePFTmeasurestocategorizeowability.
Note that these properties, which may vary with changes in temperature and humidity, include:
• Unconnedfailurestrength
• Major Principal Consolidating Stress
• Time Consolidation
• Angle of internal friction
• Angle of wall friction
• Cohesive strength
• Bulk density
Themostrecognizedindicationofpowderowabilityistheunconnedfailurestrengthwhen
viewedasafunctionoftheconsolidatingstress,knownastheowfunction.Wallfriction,internal
friction,and bulkdensityarealsocommonlyusedto relatemeasurements toow behavior.
Appendix A provides a more detailed explanation of these properties and how they are measured.