BS 4359-2:1982

Foreword
Cooperating organizations
Methods
0 Introduction
1 Scope
2 Definitions
3 Symbols
4 Principles
5 Apparatus: general
6 Preparation of the powder bed
7 Measurement of permeability
8 Variables affecting the result
9 Reporting
Appendices
A Measurement of the effective solid density of a
   powder
B Lea and Nurse constant flow rate method
C Fisher sub-sieve sizer constant flow rate method
D Rigden constant volume method
E Blaine constant volume method
F Test for bed uniformity
G Sources of reference materials for air permeability
   measurements
Tables
1 Variation of air viscosity with temperature
2 Density of pure water, rho w
3 Indicated diameter correction factors for a sample
   volume v1 of 1.25 cm3
Figures
1 Permeability cells
2 Lea and Nurse apparatus with pressure drop flowmeter
3 Schematic diagrams of Fisher sub-sieve sizer and
   sample tube
4 Rigden apparatus
5 Blaine apparatus

Describes four commonly used methods for determining the permeability surface area of powders.

This Part of this British Standard describes recommended methods for determining the permeability surface area of powders by measuring the resistance offered to the flow of air through a compacted bed of the powder.

The methods are applicable to powders with permeability volume specific surfaces in the range 2 × 10⁴ m²/m³ to 5 × 10⁷ m²/m³.

Four specific methods are described in appendices B to E.

Use of the permeability methods is precluded when:

1. agglomerates are not easily broken down (unless the specific surface area required is that of the agglomerated form);
2. the particles fracture or undergo deformation when the powder bed is being compacted.

NOTE. The titles of the publications referred to in this standard are listed on the inside back cover.