China's Water Vapor Transmission Rate Testers
Water vapor transmission rate (WVTR) testers are instrumental in measuring how quickly moisture can permeate packaging materials like films, laminates and coatings. A China water vapor transmission rate tester works by exposing a material sample to high humidity conditions and measuring the rate of water vapor transmission through it over time. This indicates the material's ability to act as a moisture barrier and helps determine its suitability for different packaging applications.
Why WVTR Is So Important?
The WVTR of a packaging material is important for several reasons:
• Shelf Life - Many packaged products need to maintain a specific moisture level during storage to ensure an adequate shelf life. Materials with a lower WVTR elongate shelf life by minimizing permeation of moisture into the package.
• Protection - Packaging aims to protect products from external factors like moisture, which can cause degradation, damage or safety issues. Materials with a very low WVTR provide the best protection.
• Performance - The moisture content inside a package can impact the performance of items like electronics, foods and chemicals. Lower WVTR packaging materials help maintain optimal performance.
• Regulation - Government agencies and industry standards often specify maximum acceptable WVTR levels for certain types of packaging, ensuring product safety and consistency.
How China's WVTR Testers Work
China produces a wide selection of water vapor transmission rate testers that generally function in the following manner:
• Material Sample - A sample of the packaging material is cut to the specified dimensions and clamped or sealed to the tester.
• Humidity Chamber - The material sample is placed inside a humidity chamber that is heated and saturated with water vapor to achieve constant high humidity (often 90% or higher relative humidity).
• Water Collection - Any vapor that permeates through the material sample over time is collected on an indicating desiccant or in a chamber containing desiccant.
• Mass Monitoring - The mass of the desiccant or desiccant chamber is monitored continuously or at set time intervals. An increase in mass corresponds to the amount of permeated vapor.
• Data Processing - The data collected on mass changes over time is processed to determine the WVTR in standard units like grams per square meter per day (g/m2/day).
• Calculation - The WVTR is calculated from the slope of the change in mass over time based on the exposed surface area of the sample.
Parameters that China's WVTR testers can control include humidity levels, temperature, sample size and exposure time. More advanced options include automation, calibration certificates and software for data analysis.
Benefits of Using A WVTR Tester
Compared to alternative laboratory or physical testing methods, a China water vapor transmission rate tester offers several benefits:
• Accuracy - Instrumental testers provide highly precise and repeatable WVTR measurements within a few percent.
• Speed - Automated systems can generate results in hours instead of days or weeks for physical tests.
• Control - Test parameters like humidity, temperature and sample size are precisely regulated for optimal and consistent conditions.
• Versatility - A single WVTR tester can evaluate a wide range of packaging materials and film thicknesses.
• Data - Numerical WVTR values provide an objective benchmark for comparing different material options and assessing their efficacy as moisture barriers.