Eskom utilises two different types of synthetic fibre material: namely PPS (Polyphenylene Sulphide) and PAN (Polyacrylonitrile) both fibres containing a cascaded layer of (P84). These non-woven fabrics are used in coal fired boilers for particulate emissions reduction in the fabric filter plants. The fabric filter uses the sieving effect produced by filtration materials to remove suspended particles from the raw flue gas. Fabric filter bag manufactures and suppliers must produce filter bag material that conform to the end user’s specification. Air permeability is one of the most fundamental variables used for fabric filter bag selection as well as conformity to specification. A low permeability result indicates more resistance to gas passing through the filter media and a result lower than 10% of the new value is considered blinded or blocked.

Air permeability measurements of synthetic fibres varies between the coastal and in-land regions and tests have indicated significant variances with the results. This effect might be due to the difference in altitude between the various locations of the bag suppliers manufacturing sites. This research aims to test this hypothesis. The study experimentally investigates variations of air permeability measurements on a coastal and in-land region using fabric filter bag material with the same characteristic properties.

The methodology employed is evaluation of the rate of the air flow passing perpendicularly through a known area of fabric, adjusted to obtain a prescribed air pressure differential between the two surfaces. The rate of air flow is measured, and the air permeability of the fabric is determined. An in-house method derived from the standard ISO 9237:1995 Textiles - Determination of the permeability of fabrics to air as well as SANS 5265:2007 Air permeability of textile fabrics will be used the analyses.

Four laboratories are selected to participate in the study, these laboratories are situated in the coastal and in-land regions respectively. Two laboratories at in-land and two laboratories at coastal regions will be utilised. Five specimen of fabric filter bag material made up of PPS and PAN shall be prepared and analysed in these laboratories. The air permeability results shall be evaluated and compared against each other to determine the effect of altitude when characterizing a filter bag material.

The Supplier Assessment is a requirement for a comprehensive test and evaluation program that will ensure that the products used in Eskom are fit for purpose and comply with the specification. The research will assist the end users of the fabric filter bags to select fabric filter bag material appropriately and accurately with a complete characterization. The outcome of the investigation is also important in informing the design and operation of the fabric filter plant system.