Moisture Analysers / Balances

Moisture balances, more commonly known as moisture analyzers or moisture meters, are precision devices utilized for determining small samples’ moisture contents via drying material samples with heaters. Moisture balances make use of the technology of infrared heating to implement the ‘loss on drying’ (LOD) method. Once a sample has been heated, it automatically loses moisture content. This loss in moisture in turn translates to the sample also losing weight and once all moisture content from the sample has been lost, the sample’s weight will no longer be altered. Moisture content is calculated by comparing the original sample’s weight to that of the final or dried sample’s weight. Gravimetric loss is also used to refer to this method.

The Inner Workings of Moisture Analyser

When using moisture balances, a technician first set the parameters for drying and puts it into memory. After which, the technician puts the sample in the weighing chamber to begin the test. The drying temperature will be instantly regulated, while the mode, the current chamber’s temperature, elapsed test time, and the results will displayed throughout the test. The technician will be informed once the test is done. This can be due to one, the sample’s weight has stopped changing, two, when the sample has been completely dried, or when the elapsed time that the technician has been used up. The final values or results are then displayed until such time that the moisture balance is reset.

Once test results are given by moisture balances, it is a common rule to reject the results and perform another round of testing. This is due to the fact that errors are common due to stabilizing heat of moisture balances’ scales and drying chambers. Samples should then be placed accordingly on the surface of the scale. A common solution to common errors include the use of indirect materials such as blotting paper or sand paper throughout the drying process for sample substances that are covered with impenetrable membranes. Other solutions include experimenting with setting time on sample materials that give off moisture content slowly, setting short testing times for sample materials that can easily give off moisture content, and breaking down coarse-grained sample materials before testing them on moisture balances.

Moisture balances can likewise be interfaced to a computer system’s printer. The output of the test is capable of displaying the results as the test in conducted, and once done, a summary of the results will then be sent directly to a printer or a computer machine with an installed printer. The summary typically contains the following information regarding the test results: test mode, percentage solids or percentage moisture, initial mass in grams, final mass in grams, drying temperature in centigrade, elapsed drying time in seconds, as well as the time interval among two subsequent measurements in seconds.

Notes on Preparing Sample Materials Before Drying on Moisture Balances

Loose or dense solid sample materials are typically dried in their natural form. The mass of sample materials can’t be too big, so breaking them down is generally recommended to make spreading after taking measurements smaller. The surface of the moisture balance’s scale should then be covered with only a thin layer of the sample material. It is likewise important to note that the process of defining moisture content will be faster or slower depending on the sample material’s physical structure. Also, the sample material’s surface size and thickness significantly influences the precision of the measurement, as well as the drying speed.

In some cases for liquid or semi-fluid sample materials, some amount of grease are found and this makes the process of defining the sample material’s moisture content harder than it usually is. In this context, it is recommended to introduce additional materials capable of enlarging the sample material’s active surface in which the moisture content will be tested. Usual additional materials include blotting paper, sand paper, or quartz sand by itself. Prior to drying on moisture balances, the additional materials should also be dry.

Parameters for Drying on Moisture Balances

The temperature used for drying sample materials is dependent on the type of material to be sampled on moisture balances. Drying temperatures which are too low only results in partial evaporation process, while hand, drying temperatures that are too high results in deflagration substance or overheated samples. Temperatures that are too high may also cause chemical reactions that alter the sample’s appearance. In general, drying temperatures are estimated by trade and factory rules. In the event that a specific sample has no given temperatures, then experimenting is recommended.

The time for sample testing with moisture balances is the range of time between measurements of the material’s mass. Moisture balances automatically treat sample materials as dried. Sample testing times that are too short may result in calculation errors since the process is abruptly finished, on the other hand, sample testing times that are too long may likewise result in errors in the final measurement since it measures the moisture content back and forth even if it is done measuring, until such time that the testing time is finished.

Another important issue worth reiterating is factoring in the correct drying temperature. For example, dark colored sample materials absorbs more heat than light colored ones, and can be overheated significantly with inaccurate temperatures. To define the correct drying temperatures, you should preferably use a control thermometer with sonde. First, program all parameters for drying and the put the sample material on the scale to begin the drying process. After the drying process, note the time of measurement and then get the next sample material. Put the sample material in the scale, this time with a larger layout. Next, insert the thermometer’s sonde through the moisture balance’s cover and dip it in the material, turn on the thermometer and begin the drying process again. Afterwards, confirm the temperature values on both the control thermometer and the keyboard, compare the values between the first and second samples, and then count the factor’s value.

Additional equipment used in conjunction with moisture balances to obtain the most accurate results includes anti-vibration tables, control thermometers, printers, computer machines, single pans, and calibration weights.