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Fluidized Hall Flowmeter |
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Hall Flowmeters are industry standard measurement devices for evaluating the flow characteristics and apparent density of free-flowing powders. |
 The “Fluidized Hall Flowmeter” has been developed by MATSYS to measure the adjusted flow rate of free-flowing and non-free-flowing powders, and to evaluate the potential of using fluidization for die filling applications. It is commonly used to evaluate variation in powder flow characteristics from batch to batch, especially for non-free-flowing powders.
The pressure and flow rate of fluidization can be adjusted so that the best possible flow rate can be achieved for a specific powder. Many powders that are incapable of flowing through a standard Hall Flowmeter can be made to flow freely using fludization.
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 Fluidization uses dry gas at low pressure and flow rate to achieve “Mass Flow.” The injection of dry gas reduces interparticle friction and powder/wall friction, and eliminates the stick/slip motion and rat holes commonly observed as powder is discharged from a funnel.
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Hall Flowmeter Geometry
 Flow rate - The time required to transfer a pre-measured 50 gram charge of powder material through a 2.5 mm orifice. ASTM B 213, MPIF 03
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Powder Flow under Gravity
 Powder column tends to collapse at the center, supported on the sides by sidewall friction and interparticulate interference.
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”Fluidized Hall Flowmeter”
 Fluidizing gas adds space between the powder particles and reduces interparticulate activity, thus allowing them to flow and distribute uniformly within the volume.
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 The “Fluidized Hall Flowmeter” system includes a Fluidized Funnel with opening between 0.1” and 0.5” diameter, a stand with a funnel holder, and a control box with regulator, gas pressure gage and gas flowmeter.
It should be noted that (1) the flow rates measured at zero gas pressure are comparable to those measured with the standard Hall Flowmeter; (2) the large funnel opening is used for poor-flowing and non-free-flowing powders; and (3) the gas pressure and flow rate are adjusted such that non-free-flowing powder will flow as a free-flowing powder; and no bubbling is observed during powder flow.
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