Notice on Relative Humidity Generation Method for TSY-W3

Three methods can be applied to generate relative humidity for the lower chamber of TSY-W3 when performing the water vapor transmission test, by using saturated salt solution, distilled water, and sulfuric acid solution with different concentrations. To achieve 100% relative humidity, distilled water is recommended. For other required relative humidity, it is recommended to use the saturated salt solution soaked ceramic dish. Please notice that only personnel with chemistry specialty should be allowed to operate sulfuric acid due to its highly corrosive property. During the test, extreme care should be taken for the following aspects:

1. Preparing the solution

·Distilled water should be used for only once to prevent humidity error caused by unfavorable ions;
·Salt bulk should be added into water with gentle stirring while preparing saturated salt solution. Keep adding salt bulk until the solution is saturated with salt crystals separating out. Alternatively, heat up the solution to 2-3 degrees higher. The solution is saturated if salt crystals separate out after cooling down.
·The solution should be kept at ambient condition.

2. Soaking the ceramic dish

·Transfer the ceramic dish carefully into the saturated salt solution with forceps and soak for more than 30 min at ambient condition;
·Extreme care should be taken when transferring the ceramic dish due to its fragility;
·The ceramic dish should be placed in a PTFE vessel rather than directly in the lower chamber.

3. Maintaining the ceramic dish

·The ceramic dish should be soaked every once a week to maintain the relative humidity to avoid experimental errors;

The ceramic dish can be reused to generate a different relative humidity after cleaning. To perform the cleaning, first rinse the dish with pure water, soak for 4 hours, rinse several times, and dry up in 80℃ oven.