Water Vapor Transmission Rate Tester – Infrared (TDLAS) Method

No periodic recalibration is required. The sensor performs automatic attenuation compensation, so data do not decay continuously over time. Routine work is limited to a verification with a reference film per your SOP — much less maintenance than sensors needing frequent calibration.

Yes — 99.999% high-purity nitrogen as carrier gas at 0.1–0.2 MPa and 0–100 (or 0–300) cm³/min. One standard cylinder lasts a considerable time for a single instrument, so running cost is manageable; a central gas supply makes it even easier.

The infrared (TDLAS) method is a sensor method: it does not wait for mass to accumulate, so a single specimen typically finishes within hours, whereas the cup method can take days on high-barrier materials. Its ranges are 0.005–100 g/m²·24h for films and 0.00005–0.5 g/pkg·24h for containers, with resolutions of 0.001 and 0.00001 respectively. Three situations favour it: high-barrier structures (metallised film, foil laminates, oxide-coated films); R&D and incoming inspection that need fast answers; and labs with high test throughput. Where the number must go into a regulatory file and needs absolute-method backing, gravimetric remains the more defensible reference.

Choose by range and purpose. The gravimetric cup method is closest to the pharmacopoeia and ASTM E96 classic: a wide range, finished containers can be measured directly, but each run is long — best for compliance comparison and referee testing. The electrolytic method is an absolute coulometric method suited to low-transmission films and containers. The infrared (TDLAS) method responds fast and suits trace water vapour in high-barrier materials and high-throughput work. Pick the cup method when compliance leads, electrolytic or infrared when line efficiency leads.

The differential-pressure method creates a pressure difference across the specimen and tracks the pressure rise on the low-pressure side; one instrument measures oxygen, carbon dioxide, nitrogen and other non-toxic gases, making it the general-purpose choice. The equal-pressure method keeps both sides at the same pressure and uses a coulometric sensor for oxygen only, giving higher sensitivity for the extremely low OTR of high-barrier materials. Two rules: choose differential pressure when you need several gases, coulometric when you measure oxygen only and need the lowest detection limit.

Because the transmitted amount is extremely small, you must wait until permeation reaches steady state and the accumulated signal exceeds the instrument resolution; temperature and humidity equilibration and the system background (residual oxygen or water vapour) also take time. Practical ways to shorten it: raise the test temperature and note it in the report, reduce background and leaks, use a more sensitive sensor, and add parallel test chambers. No speed-up should compromise the steady-state criterion.

The effect is significant: conditions must match the method standard and be stated in the report. Higher temperature raises transmission; for hydrophilic materials, a change in relative humidity markedly changes both water vapour and oxygen transmission. This instrument controls 15–45 °C to ±0.3 °C and covers 35%–90% RH (some models also offer 0% RH). Before comparing data between laboratories, check that both used the same temperature and humidity.

Yes. Standard models ship as-is, while chamber count, specimen size, fixtures, temperature range and software modules (including the GMP Computerized System module) can be tailored to your SOP and URS. IQ/OQ/PQ validation documentation packages are available.

Standard models usually ship in 4–8 weeks; customised builds depend on the agreed scope. Instruments are packed in export wooden cases and can move by sea, air or rail. We supply proforma invoice, packing list and certificate of origin (CO / Form E), and work under EXW, FOB, CIF or DAP terms.

We provide remote installation guidance, bilingual (Chinese/English) manuals and video training; on-site commissioning by our engineers is available. Users can self-calibrate with standard weights, reference films or calibrated leak standards, and third-party calibration certificates can be supplied.

The instrument carries a 12-month warranty from acceptance plus lifetime maintenance support. Consumables (molecular sieve, desiccant, sealing grease, printer paper) are kept in long-term stock, and key components are international brands available worldwide. We respond to technical enquiries within 24 hours.

Yes. Every instrument lists its applicable standards on the specification page (ASTM, ISO, GB, YBB, Chinese Pharmacopoeia, USP, EP, JIS, DIN, TAPPI and more). The software outputs raw records and reports suitable for audit trails, with an optional GMP / FDA 21 CFR Part 11 compliance module.

The software ships with Chinese and English interfaces; other languages can be added on request. Data export is available over RS232, USB, Ethernet or Wi-Fi, and reports can be exported to Excel, PDF or structured files for LIMS integration.