Overview
ISO 23742:2024 - Test method for the evaluation of permeability and filtration efficiency distribution of bag filter medium - specifies a standardized measuring method to determine the spatial distribution of key properties in bag filter media. It applies to both woven and non‑woven filter medium and focuses on measuring distributions (not ranking or grading products) of thickness, area mass, gas permeability and collection (filtration) efficiency. The standard also defines how to sample specimen sheets (position, size and number) to obtain accurate performance distributions.
Key topics and requirements
- Measurement scope
- Distribution measurements for thickness, area mass, gas permeability, and optional filtration efficiency.
- Tests produce local performance distributions rather than only average values.
- Sampling protocol
- Sample sheets taken from at least 20 cm inside roll ends and sides; avoid selvedge.
- Lateral spacing between sample sheets: at least 50 cm, maximum 5 sheets across a roll.
- Minimum sample sheet size: 30 cm × 30 cm.
- Number of sample sheets determined based on sampling theory (see Annex A) to meet required reliability.
- Specimen preparation and conditioning
- Conditioning and testing in a standard atmosphere (referenced to ISO 139).
- Specimen strip sizes and conditioning procedures specified to ensure comparable results.
- Measurement methods
- Thickness measurement procedures and apparatus (see Clause 6; reference ISO 5084 for textile thickness).
- Area mass measurement using precision balance and calibrated ruler.
- Gas permeability testing with specified specimen holders, flow measurement and pressure instrumentation.
- Optional filtration efficiency testing method and recommended test sequence.
- Reporting
- Expression of distribution results and an example test report (Annexes D and E).
- Guidance on measurement management and equipment accuracy (reference ISO 10012).
Applications and users
ISO 23742:2024 is practical for:
- Filter media manufacturers - to characterize production non‑uniformity and improve quality control.
- Baghouse and dust collector designers/operators - to predict localized performance, clogging risk and service life.
- Testing laboratories and QA/QC teams - for standardized performance mapping and reproducible test reports.
- Procurement and R&D - to compare morphological information and ensure specification compliance (note: the standard is not intended for grading different media).
- Environmental and industrial compliance teams - to better understand filtration behavior in applications like incineration, power plants, cement and metallurgical plants.
Related standards
- ISO 139 - Standard atmospheres for conditioning and testing
- ISO 5084 - Determination of thickness of textiles and textile products
- ISO 10012 - Measurement management systems - Requirements for measurement processes and measuring equipment
Keywords: ISO 23742:2024, bag filter medium, permeability distribution, filtration efficiency distribution, gas permeability, area mass, thickness measurement, sampling procedure, non‑woven filter medium.
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