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Home  >>  Products  >>  Density  >>  Flowability Tester
Flowability Tester

Model BEP2

Powder Angle of Repose
BEP2 with Cylinder Attachment

Specifically designed to address the specifications in and comments raised by the European Pharmacopoeia Chapter 2.9.36 and US Pharmacopeia Chapter <1174> on Powder Flow.

The widespread use of powders in the pharmaceutical industry has led to a proliferation of test methods for measuring powder flow. The harmonized chapters in the Pharmacopoeias on Powder Flow (USP Chapter <1174> and Ph.Eur. Chapter 2.9.36) list four well-defined methods for powder testing aimed at trying to bring about some degree of standardization within the existing test methodology:

• Flow through an orifice
• Angle of Repose
• Shear Cell
• Compressibility Index and Hausner Ratio




The Flowability Tester BEP2 provides a range of options for testing pharmaceutical powders including three of the four methods quoted in the Pharmacopoeias - flow through an orifice, angle of repose and shear cell - in a single, cost effective unit. In addition to providing the test methods detailed in the harmonised pharmacopoeia chapters, it is also suitable for flowability testing according to Ph.Eur. 2.9.16. An optional balance/timer simplifies time vs mass testing. The BEP2 is an easy to use, small footprint instrument with interchangeable cylinder, funnel, angle-of-repose and shear cell attachments. A description of each attachment can be found below.


Cylinder Attachment (Flow Through an Orifice)


Measuring the ability and the time taken for a powder to flow through an orifice of known size is a useful method of quantifying powder flow. At the same time, it is important to recognise that the ability of the powder to flow through the orifice can be affected by factors other than the characteristics of the powder itself. Such factors include the shape and material employed in the construction of the powder container, the diameter and height of the powder bed and the shape of the orifice concerned.

The Pharmacopoeias suggest that the use of a circular cylinder as the powder container encourages powder over powder flow - as opposed to powder over container wall - minimizing any effect brought about by differences in the material used to produce the powder container. As the title suggests, this technique is only suitable for materials that flow, not cohesive materials. Assuming this to be the case, then the Pharmacopoeias suggest that providing:


a) The height of the powder bed (the "head") is much greater than that of the orifice
b) The diameter of the opening is greater than six times the diameter of the particles
c) The diameter of the cylinder is greater than two times the diameter of the opening then any difference in results brought about by either powder bed or orifice can be considered negligible.

The Cylinder Attachment has been designed to take all of these factors into account. The Cylinder Attachment comprises a stainless steel cylinder measuring 76 mm long x 57 mm i.d. and having a capacity of 200 mL. The bottom of the cylinder is sealed with a collar designed to accept disks having various orifice diameters. The attachment comes complete with a set of 20 interchangeable stainless steel disks each containing a precision drilled hole in the center covering the following sizes: 4, 5, 6, 7, 8, 9, 10,12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34 and 36 mm. A shutter covers the hole during filling. This can be smoothly removed without vibration to allow the powder to flow through the selected hole. The Cylinder Attachment can be used in two ways: (a) to carry out quantitative flowability tests based on mass vs time or (b) to determine the intrinsic flowability of the powder concerned in the form of a flowability index based on comparative measurements.


a) Mass vs. Time

Powder Angle of Repose
BEP2 with Cylinder and Balance/Time Attachments

Operation is extremely simple. Select a disk having the appropriate orifice size for the powder concerned (start with 18 mm and work up or down accordingly if size unknown) and secure it to the bottom of the cylinder using the collar provided for this purpose. Adjust the shutter so that the hole in the bottom of the cylinder nozzle is covered.

Introduce the test sample (100 grams unless inappropriate) into the flow cylinder. Now open the shutter and measure the time required for the entire sample to flow out of the funnel using a suitable stopwatch.

Carry out three measurements: express the flow rate results in terms of mass vs. time i.e. grams per second.


b) Intrinsic Flowability

Powder Angle of Repose
Anti-static Grounding Kit for BEP2

The Cylinder Attachment provides a simple and repeatable technique for the determination of powder flow characteristics.

As such it takes into account most of the physical characteristics affecting flowability, such as particle size, shape, fines, unit surface, actual and bulk density, porosity, settling, and electrostatic charge, without a direct quantitative measurement of any of these parameters.

The determination of Intrinsic Flowability is based upon the ability of a powder to fall freely through a hole in a plate. The results are expressed in terms of a Flowability Index given as the diameter (in mm) of the smallest hole the powder falls through freely on three successive attempts.

For new formulations, it is recommended to start with the 18 mm disk. Once the disk is in position and with the shutter in the closed position, a 50 gram sample is introduced into the test cylinder using the funnel provided for this purpose.

After waiting for approx. 30 seconds to allow for any possible formulation of flocculi, the shutter is opened. The test is positive if the powder flows through the hole leaving a residue in the form of an upside-down truncated cone. A powder that flocculates in bulk will, on the other hand, fall abruptly forming a cylindrical cavity.

In this instance, as is the case if the powder refuses to flow through the hole, the test is adjudged to be negative. In the case of a positive result, the test must be repeated with smaller and smaller disk holes until the result is negative. For negative results, increase the size of the disc hole until the test is positive.

The Flowability Index has been used successfully to establish dry powder characteristics prior to setting up filling equipment such as capsule fillers, tablet presses and dry packaging machines, thus avoiding high coefficients of variation.


Funnel Attachment (Flow Through an Orifice)

Powder Angle of Repose
BEP2 with Funnel ad Balance/Timer Attachements

In certain instances where, for example, the purpose of the test is to simulate flow in a hopper or other production situation, it may be preferable to use a funnel in the form of a truncated cone.

The Funnel Attachment is based on the stainless steel flow funnel and nozzle described in the European Pharmacopoeia Chapter 2.9.16 for Flowability. It has a capacity of approx. 400 mL.

The attachment is supplied with three nozzles corresponding to aperture sizes of 10, 15 and 25 mm respectively. Both funnel and nozzles are manufactured from pharmaceutical grade 316 stainless steel. The nozzles can be quickly interchanged using the connecting nut provided for that purpose.

The opening at the bottom of the funnel is secured by means of an adjustable shutter, which is closed during the filling operation. The test is carried out in a similar manner to that of Method A (Mass vs Time) of the cylinder attachment.


Balance/Timer Attachment


By adding a balance and a timer linked to a microswitch located on the shutter mechanism, it is now possible to conduct time vs. mass tests using either cylinder or funnel methods without the need for an external stopwatch. The balance/timer option allows the use of the unit in four modes:

• Determination of the flow time of a predetermined sample weight
• Determination of the flow time of a predetermined sample volume
• Determination of the weight of sample in a predetermined time
• Plot of time against sample weight (weight/time)


Angle of Repose Attachment (ASTM D6393)

Powder Angle of Repose
BEP2 with Funnel and Angle of Repose Attachments

The Angle of Repose is the angle (relative to the horizontal base) of the conical pile produced when a granular material is poured onto a horizontal surface. It is related to the density, surface area and coefficient of friction of the material concerned.

The Angle of Repose Attachment comprises a 100 mm diameter circular test platform together with a digital height gauge, having a range of 0-300 mm and an accuracy of 0.03 mm. The test platform has a protruding outer lip in order to retain a layer of powder upon which the cone is formed. Surplus powder is collected in a tray below the test platform.

For this particular test, the funnel is normally equipped with a special 10 mm i.d. nozzle mounted 75 mm above the test platform. If necessary, the contents may be stirred to assist in the powder flow (see left).

The tangent of the angle of repose (in degrees) can be determined by reading off the height of the powder cone in mm from the digital display of the height gauge and dividing it by 50. The Table the flow properties associated with corresponding Angles of Repose.

Powder Angle of Repose

Tangent Angle

Manually operated Stirrer for Funnel Attachment

If necessary, the contents may be stirred to assist in the powder flow using the manually operated stirrer attachment.


Flow Properties & Angle of Repose

Flow Properties & Angle of Repose
Flow Property Angle of Repose
Excellent 25 - 30
Good 31 - 35
Fair - aid not needed 36 - 40
Passable - may hang up 41 - 45
Poor - must agitate, vibrate 56 - 55
Very poor 56 - 65
Very, very poor > 66


Shear Cell Attachment

Shear cell methodology is widely used in the pharmaceutical industry to determine the flow properties of fine grained powders and bulk solids and how they will behave in bins, hoppers, feeders and other handling equipment. The ability of a material to flow through such devices is dependent on the bulk density of the material and its shear strength.

The Shear Cell employed with the BEP2 comprises a cylindrical chamber (manufactured from clear acrylic) measuring 140 mm i.d. and 32.5 mm high and capable of holding 500 mL of the sample. In the floor of the chamber, there is a 100 mm hole, which can be sealed during the consolidation process using an acrylic disk provided for this purpose.

The test is based on measuring the force required to shear a circular disk through a prepared sample of bulk material. It comprises two stages: (a) sample consolidation (bulk density measurement) and (b) failure inducement (shear strength). The sample is first subjected to a consolidated load such that the bulk density of the material can be determined - ideally, this should be similar to the loads experienced by the material in practice. Alternatively, a standard reference can be employed e.g. 10 kg.

The acrylic disc sealing the bottom of the test cell is now removed and load steadily applied to the test sample by pouring sand through a funnel into a container of appropriate proportions resting on top of the sample until such time as the sample fails (shears). The results should be expressed in terms of bulk density, shear strength and if appropriate, estimate of device outlet required.

BEP2 with Funnel and Shear Cell Attachments

Shear Cell



Prices subject to change    Prices listed in US dollars for domestic shipments within US, Canada, & Mexico only    Export orders require quotations - click here for a quote     For more info call us 1-800-762-2478 or 954-946-9454.
Item Number Item Prices
WG-701650 Flowability Tester Model BEP2 Stand and Upright $630.00
Choice of Required Accessories for Floawability Tester Model BEP2 Stand and Upright:
WG-701651 Cylinder Attachment (Flow through an Orifice) 3,495.00
WG-701652 Funnel Attachment (Flow through an Orifice) 2,450.00
WG-701625 Manually operated Stirrer for Funnel Attachment 785.00
WG-701653 Balance/Timer Attachment 1,215.00
WG-701654 Angle of Repose Attachment (Requires the Funnel Attachment (WG-701652) to operate) 2,645.00
WG-701655 Shear Cell Attachment (Requires the Funnel Attachment (WG-701652) to operate) 2,435.00
WG-701657 Anti-static Grounding Kit for BEP2 175.00
WG-701658 IQ/OQ Documentation Pack 435.00
WG-701659 Qualification Tools for the BEP2 contains UKAS calibrated 200g, 500g and 1Kg Stainless Steel weights, 25mm & 60mm Gage Blocks with UKAS certificate & calibrated digital stopwatch 1,255.00
WG-701611 Angle of Repose Flowability Tester Complete - Instrument comes complete with: Flowability Tester Model BEP2, Funnel Attachment and Angle of Repose Attachment. 5,095.00


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