1. Scope

1.1 This method covers the apparatus and procedures for measuring the pressure drop and deriving the permeability of a powder bed with respect to consolidation stress and/or superficial gas velocity, using the FT4 Powder Rheometer. 1.2 The parameters generated during this test are most commonly used to assist with the design and operation of powder processing and transport operations. They can also provide relative classification or comparison of the flow behaviour of different powders, or different batches of the same powder, that are subjected to similar stress and flow regimes within their processing equipment. 1.3 The 50 mm apparatus described in this Standard is suitable for measuring the properties of powders and other bulk solids with a maximum particle size of 6 mm. It is possible to test powders which have a small proportion of particles of 6-10 mm, but they should be present in the bulk sample as no more than 5 % of the total mass in samples with a normal (Gaussian) size distribution. 1.4 This practice offers a set of instructions for performing a specific operation. This document cannot replace education or experience and should be used in conjunction with professional judgement. Not all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a projects many unique aspects. The word Standard in the title of this document means only that the document has been approved through the ASTM consensus process. 1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026. 1.5.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives; and it is common practice to increase or decrease significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design. 1.6 Units The values stated in SI units are to be regarded as standard. No other units of measure are included in this standard. 1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Keywords

Freeman Technology; FT4 Powder Rheometer; normal stress; permeability; powder; powder bed; pressure drop; superficial gas velocity.

Rationale

This test method describes an established method for the measurement of powder gas permeability. The method is widely used in industry by many industrial practitioners across different sectors. It helps provide bulk powder properties that are relevant to powder behavior in hoppers, filling applications, tablet compression, conveying, and so forth.

The title and scope are in draft form and are under development within this ASTM Committee.