• Purpose
Hall Flowmeters are industry standard measurement devices for evaluating the flow characteristics and apparent density of free-flowing powders.
• Application

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 fluidization.
• Concept

Fluidization uses dry gas at low pressure and flow rate to achieve “Mass Flow.” The injection of dry gas reduces inter-particle friction and powder/wall friction, and eliminates the stick/slip motion and rat holes commonly observed as powder is discharged from a funnel.
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
Powder Flow under Gravity
Powder column tends to collapse at the center, supported on the sides by sidewall friction and interparticulate interference.
”Fluidized Hall Flowmeter”
Fluidizing gas adds space between the powder particles and reduces inter-particulate activity, thus allowing them to flow and distribute uniformly within the volume.
• Standard Fluidized Hall Flowmeter System

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 gauge 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.

• Automated Fluidized Hall Flowmeter System

Incorporates our standard setup with the addition of an optical laser sensor and digital cycle counter to record flow rates with a timing accuracy of +/- 0.01%, and reduces human interaction and error during data collection.

 

The new Automated Fluidized Hall Flow Meter allows the user to perform flow characteristic testing and rate analysis nearly hands free.

Portable and self-contained, the system simply needs to be provided with dry gas at 60 to 150 psi either from a bottle or a compressor with a dryer/filter assembly.

 

Matsys uses these systems for customer powder evaluation services and is now offering them to the public. The system is affordable, one of a kind and can accommodate a variety of particulate material ranging from the size of a grain of sand to sub-micron powders.Funnels are available as replaceable modules with porosity ratings offered range from 15 micron down to 0.5 micron average.

 

The system is ideal for those who work with Pharmaceuticals, Powder Metal, Food/Spices, Makeup/Cosmetics, Polymers, etc. Please contact Matsys for more information on availability and pricing.
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