Gurley Model 4340 Digital Air Permeability and Smoothness Tester
| Brand | Gurley |
|---|---|
| Origin | USA |
| Model | 4340 |
| Pressure Requirement | ≥40.5 psi |
| Units Supported | Gurley, Sheffield, Bendtsen, Bekk |
| Compliance | ASTM D726, TAPPI T460, ISO 5636-5, ISO 8791-2 |
| Measurement Principle | Constant-pressure air flow through porous sheet materials |
Overview
The Gurley Model 4340 Digital Air Permeability and Smoothness Tester is a precision-engineered benchtop instrument designed for quantitative assessment of air permeance (commonly referred to as “air resistance” or “porosity”) and surface smoothness of flexible sheet materials—primarily paper, board, nonwovens, filter media, packaging films, and technical textiles. It operates on the fundamental principle of measuring the time required for a fixed volume of air (100 mL) to pass through a standardized test area (6.45 cm²) under a controlled, constant differential pressure of 40.5 psi (279 kPa), in accordance with ASTM D726 (Standard Test Method for Resistance of Paper to Passage of Air), TAPPI T460 (Air Permeance of Paper and Paperboard), and ISO 5636-5 (Determination of Air Permeance — Part 5: Gurley Method). For smoothness evaluation, the instrument employs the Gurley-type compression method—where a defined weight applies downward force onto the specimen while air escapes through the interface between the sample and a calibrated orifice—yielding results traceable to ISO 8791-2 (Determination of Smoothness — Part 2: Gurley Method) and TAPPI T536.
Key Features
- Dual-function architecture: Simultaneously supports both Gurley air permeability (in seconds per 100 mL) and Gurley/Bendtsen/Sheffield/Bekk smoothness measurement modes via interchangeable orifice assemblies and calibration routines.
- Digital microprocessor-controlled timing circuitry with ±0.01 s resolution ensures high reproducibility and eliminates operator-dependent stopwatch errors.
- Integrated pressure regulation system maintains stable test pressure at ≥40.5 psi (279 kPa) across ambient temperature fluctuations; pressure integrity verified by built-in analog gauge and optional digital transducer logging.
- Automated statistical processing: On-board calculation of mean, standard deviation, coefficient of variation (CV%), and number of replicates—fully compliant with GLP documentation requirements.
- Modular design accommodates optional accessories including motorized auto-feed station (for unattended sequential testing of up to 20 specimens), thermal printout module (for audit-ready hardcopy records), and USB data export interface.
Sample Compatibility & Compliance
The Model 4340 accepts flat, non-curling sheet specimens sized 100 mm × 100 mm or larger, with thicknesses ranging from 0.05 mm to 3.0 mm. It is routinely deployed in QC laboratories serving pulp & paper mills, medical packaging converters, filtration OEMs, and food-grade barrier film producers. All measurement protocols align with internationally recognized standards: ASTM D726 (air permeance), ISO 5636-5 (Gurley method), TAPPI T460 (air resistance), ISO 8791-2 (smoothness), and EN 14488-2 (for geotextile air permeability verification). Instrument calibration certificates are traceable to NIST standards, and routine verification procedures satisfy FDA 21 CFR Part 11 requirements when paired with validated software and electronic signature modules.
Software & Data Management
While the base Model 4340 operates as a stand-alone unit with local display and printed output, it integrates seamlessly with Gurley’s optional PC-based DataLink™ software suite. This application enables real-time acquisition, trend analysis, SPC charting (X-bar/R, Cpk), automated report generation (PDF/CSV), and secure database archiving. Audit trails—including user login, parameter changes, calibration events, and result modifications—are logged with timestamps and operator IDs, supporting full compliance with GMP/GLP and ISO/IEC 17025 accreditation frameworks. Data export conforms to LIMS-compatible formats and may be configured for direct upload into enterprise quality management systems (QMS).
Applications
- Quantifying breathability of medical gowns, surgical drapes, and sterile barrier packaging per ISO 11607-1.
- Evaluating pore uniformity and coating integrity in lithium-ion battery separator films.
- Verifying consistency of inkjet receiver papers and digital printing substrates.
- Assessing air leakage resistance in metallized PET laminates used in snack food packaging.
- Monitoring production stability in tissue manufacturing lines using moving-range control charts.
FAQ
What pressure does the Gurley 4340 use for air permeability testing?
It operates at a nominal test pressure of 40.5 psi (279 kPa), maintained within ±1% tolerance during measurement.
Can the instrument measure both Gurley and Sheffield units without hardware modification?
Yes—unit conversion is performed digitally via firmware selection; no physical orifice change is required between Gurley, Sheffield, Bendtsen, or Bekk modes.
Is calibration traceable to national standards?
All factory calibrations are NIST-traceable; users receive a certificate of calibration with uncertainty budget and reference standard identifiers.
Does the Model 4340 support 21 CFR Part 11 compliance?
When equipped with DataLink™ software, password-protected user roles, electronic signatures, and immutable audit trails, it meets core technical requirements for Part 11 validation.
What is the minimum sample thickness the instrument can accommodate?
The clamping mechanism reliably seals specimens as thin as 0.05 mm (e.g., tissue, thin foils), provided they exhibit sufficient tensile integrity to withstand 40.5 psi differential pressure without rupture.
