The slang phrase “you’re all wet” is generally not taken as a compliment – signifying instead that “you are wrong.” Wetness can also be wrongness when too much moisture is contained in products such as plastics, fabrics and wood chips. Laws define the maximum moisture content in applications including food processing and pharmaceutical manufacturing. Correct moisture content positively impacts processing results and overall product quality across a wide range of industries.
Moisture content can be measured quickly and easily using a moisture analyzer or moisture balance such as the Kern models available from Tovatech. Equipped with halogen quartz glass heaters, they provide constant even drying of the sample at pre-selected temperatures. Standard operating procedures should be established to ensure measurements are conducted at proper intervals.
It is a three-step process: placing the sample in the drying chamber, entering the test parameters on the unit’s keypad and pressing the start key.
The drying cycle is monitored by the unit’s software and kept within 1oC of the chosen setting. As the analysis proceeds the moisture balance displays the current status, keeping operators up to date on each stage of the process. The analysis automatically terminates when drying is complete and the dry weight is stable, or after the period of time specified.
Select the Heating Profile
Four heating profile options extend the utility of these moisture analyzers:
- Standard drying is the most common process and is suitable for most substances.
- The soft-drying option is intended for substances that do not tolerate rapid halogen heating. Other products may form a surface film when heated too fast. This hinders evaporation of entrapped moisture.
- Fast heating can be used for samples with moisture content between 5% and 15%. In this mode the temperature increases quickly, briefly exceeds the set drying temperature then is automatically regulated down to the set temperature.
- Step drying can be used for substances that show specific behavior during the drying process. Individual increments on the drying duration or temperature increases can be selected by the operator.
Results showing on the digital displays of these analyzers remain until a new measurement is begun. All relevant data concerning initial mass, residual mass, test parameters and results can be printed out via an RS-232 interface connected to a PC. This enables operators to produce a graph plotting results against time. This valuable information on the speed of drying and confirmation of dry weight stability conforms to GLP/ISO record-keeping requirements.
Keep it Honest
Weight calibration programs are available to quickly set the accuracy of the moisture analyzer using external calibration weights. Periodic temperature calibration is also recommended. In summary, for research, manufacturing, and quality control applications it is essential to determine moisture content simply and reliably. Kern moisture analyzers do that by providing moisture content data as a percentage of initial mass or of the residual dry mass. All models have a readout of 0.001 g or 0.01%.
Where do you use moisture analyzers in your operations? Can you recall an instance where these analyzers provided needed proof of proper manufacturing procedures? Please share any unusual experiences you’ve had using a moisture analyzer.