What is the principle of the moisture meter and how to use the moisture meter

1. Adopt the method of heating and drying;

2. Adopt chemical methods;

It is widely used in various production and experimental processes: such as medicine, plastics, chemicals, food (surimi, dehydrated vegetables, meat and aquatic product processing, noodles, flour, biscuits, moon cakes, etc.), grain, feed, seeds, rapeseed, tobacco, tea and textile, agriculture and forestry, papermaking, rubber, textile, powder and other 、、、

1. It is widely used in the industry.

2. Fully automatic test mode.

3. High efficiency and fast speed.

4. No installation, commissioning and training are required.

1. Adjust the water balance: Before turning on the machine, observe the level at the front end of the moisture meter.

Whether the small blister in the ring is in the center position, if not, adjust the bottom adjustment nut of the moisture meter so that the blister is in the center of the ring, and the left hand is adjusted to raise the instrument, otherwise, the right hand is lowered.

2. Boot preheating: Due to the high accuracy, the 1/10,000 moisture meter needs at least half an hour of preheating time when it is turned on for the first time or after a long time of power failure and idleness. Therefore, under normal circumstances, the laboratory moisture meter should avoid frequent power cuts.

3. Start weighing: Press the "start" button to turn on the instrument; Wait for 10 seconds and the instrument will complete the boot process on its own. When the screen shows 0, it indicates that the moisture meter is fully powered on and ready to be measured, and it can be weighed and dried; Spread a layer of fiberglass paper on the weighing tray first, press the zero button on both sides of the display to reset the weight to zero, and when the display shows 0, add the reagent to be measured on the weighing paper to weigh.

After the test, press the ON button to turn off the display.

The use of the moisture meter is directly related to the selection of the moisture meter, and the operation of the fully automatic moisture meter is more convenient, such as:

1. The operation process of the moisture analyzer:

1. The instrument is placed on a stable water platform.

2. Connect the power supply and turn it on.

3. Sampling. 4. Close the heating cylinder, and the instrument will be tested automatically.

2. Conditions for the use of moisture analyzer:

1. Use environment: dust-free, dry, no vibration.

2. There is no flowing wind blowing.

3. There is no magnetic field around.

3. Types of moisture meters:

1. Infrared moisture meter;

2. Halogen moisture meter;

3. Microwave moisture meter;

4. Karl Fischer titrator meter;

Fourth, the principle of moisture meter, currently commonly used are:

1. Heating method: moisture meter;

2. Chemical moisture meter;

The rapid moisture analyzer has a beautiful appearance, with automatic weighing, automatic validity, diversified drying methods and other functions, the rapid moisture meter measures the weight of the sample at the same time, the heating unit and the water evaporation channel quickly dry the sample.

The principle is as follows: an organic solvent and water are not miscible at room temperature, but can form azeotrope, its density is smaller than water, the common ones are toluene, when the water separator is filled with solvent, the solvent and water are stratified in the water separator, the water accumulates in the lower part of the water separator, and the solvent refluxes into the reaction system. In fact, there are two core points:

Azeotropic with water is not miscible and has a smaller density than water.

Difference between volume method and coulomb method.

Determination principle of Karl-Fischer volumetric water determination:

The determination of moisture content by the Karl-Fischer volumetric method is mainly based on the electrochemical reaction: i2 2eó2i-

When both I2 and I- are present in the solution of the reaction cell, the reaction takes place simultaneously at both the positive and negative ends of the electrode, i.e. i2 is reduced on one electrode and i- is oxidized on the other, so that there is an electric current passing between the two electrodes. If there is only i- and no i2 in the solution, no current passes between the two electrodes.

Karl-Fischer reagent contains active ingredients such as pyridine and iodine, which can be measured and dropped into the reaction cell, and can have the following chemical reaction with the water in the solution to be measured

h2o＋so2＋i2＋3c5h5n→2c5h5n·hi＋c5h5n·so3

c5h5n·so3+ch3oh→c5h5n·hso4ch3

c5h5n·hi→c5h5n·h++ i-

The reaction continues with the continuous consumption of water to produce i- until the end of the titration of the reaction, when the water is consumed. At this time, there is a trace amount of unreacted Karl Fischer reagent in the solution, so that the presence of I2 and I- at the same time, the solution between the two platinum electrodes begins to conduct electricity, and the current indicates that the end point is reached, and the titration is stopped. The water content in the solution is thus calibrated by measuring the volume (volume) of the consumed Karl Fischer reagent.

The determination principle of the Karl Fischer Coulometric method (electric power method).

The electric power method is based on the fact that after dissolving the sample in the electrolyte of a special solvent containing a certain amount of iodine, the water consumes iodine, but the required iodine is no longer titrated with the iodine-containing reagent that has been calibrated, but through the electrolysis process, the iodine ions in the solution are anodicized to iodine: 2i--2e-i2

The resulting iodine reacts with the water in the sample. Its endpoint is indicated by a double platinum electrode. When the iodine concentration in the electrolyte returns to the original concentration, the electrolysis is stopped. Then according to Faraday's law of electrolysis:

The moisture content of the sample to be tested is calculated.

The principle and purchase of moisture meter.

I saw this on the Internet, and I don't know if it's or not.