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Frequently asked questions

This section contains questions about Design Bureau "Fizelektronpribor" products. If there is no answer for your question - please contact us. As soon as Design Bureau engineer will respond to it, we will notify you by email.

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  • Dear Sirs, I am interested in your products, especially in-line moisture meters to make "Measuring of burden raw material moisture on a conveyor" for agglomeration production. I would like to receive additional information on the possibilities of your sensors for solving this problem with approximate cost and equipment list. I am also interested in the ability to integrate your equipment with Siemens controllers.

    Дата публикации: 15.05.2014

    According to operating principle, the device belongs to dielectric ones. As capacitive sensors, it measures permittivity of the substance and then determines the moisture using permittivity.

    Unlike other dielectric devices, our instrument is also a radio device. It measures the absolute value of the permittivity. Moreover, not a narrow strip of material near the transmitter (ceramic plate) is analyzed, but a large amount of not less than 10 liters.

    This is important since bulk material moisture typically is not uniform in volume. Also the moisture meter is used on lump materials with granular size up to 5 cm.

    The device can be installed above the conveyor belt. However, there are changes of density (lumpiness) of bulk material and amount of air between the particles during belt movement. For any of moisture meter (except for optical) this leads to measurement errors.

    Therefore if high accuracy is needed, we recommend to install the sensor in the hopper, dispenser, or at least in the tray in which the density of the material is more stable than on the conveyor belt.

    Its output signals: digital MODBUS RTU and current 4-20 mA signals are simultaneously transmitted.

    In your case of application to estimate the accuracy it is necessary to know the name of burden material and moisture measuring range.

  • Using of moisture meters with ceramic protective plates has led to loss of ACS dosing inert materials and water accuracy because of high irregularity of measurement results. What can you say about the accuracy of FIZEPR-SW100 during the measurement of bulk materials? Its operating principle? Its price?

    Дата публикации: 15.05.2014

    As to the problems with the measurement of moisture using sensors you listed, sensors of their type have only surface layer of the ceramic plate as a measurement area.

    It is easy to verify in the following experiment. Put a stack of sheets of paper or magazines that has a thickness of 1-2 cm on a ceramic sensor surface. This stack simulates the surface layer of the material. Then put your hand over the sensor and see how its readings change.

    In order to avoid a mistake with amount of water, it is necessary to increase the volume of material analyzed. We performed several experiments: we took some samples of crushed stone and sand from different areas of the dispenser (this is easy to do: after opening the gate several samples of rolling sand and gravel were taken). Dosing unit volume is about 1 cubic meter. We have known that for sand and carbonate gravel moisture within this small volume can vary more than by 1% with an average moisture of 7.6% (moisture value was determined by drying).

    As for the moisture meter FIZEPR-SW100, its measurement area includes material disposed between its probe and the hopper wall and also located in a cylindrical area about 20-30 cm in radius around the probe. The sensor with the flat-topped probe (nominal probe length - 24 cm) analyzes the area of about 20 liters. The direct probe (from one hopper wall to another) determines the average moisture at a significantly greater volume of about 1 cubic meter (depending on the size of the probe and the hopper).

    The price of any version of the moisture meter for bulk materials is 68,971 RUB, including VAT.

    Operating principle overview.

    The probe (stick) is a half-wave TEM-wave resonator wherein the second conductor is the tank wall. The stick end is short-circuited because it is connected to the tank wall. Complex refractive index is determined using resonance frequency then permittivity and moisture (by calibrating tables) are calculated. The moisture meter controller includes calibrating tables for sand, carbonate rubble and granite gravel. The user can easily edit these tables if necessary. At that PC screen draws all data – diagrams of moisture dependence on the refractive index (or permittivity) for a temperatures set.

  • How the measurement of moisture is performed? Does the sensor continuously measure moisture? Does it have an averaging algorithm?

    Дата публикации: 15.05.2014

    Moisture is determined by measuring permittivity in the metric VHF band. Moisture is measured regularly, about 1 time per second. The result is displayed as the average value of 5 measurements, but the user can optionally change the averaging base using the program for PC / Laptop.

  • Is temperature compensation provided in the moisture meter?

    Дата публикации: 15.05.2014

    There is a thermocouple inside the probe. Therefore all calibrations are referenced to the temperature.

    It should be noted that the method of measurement used is based on permittivity measurement. And compared to attenuation measurements at microwave frequencies the results less depend on temperature.

  • In what way calibration of your moisture sensor installed in the sand and gravel bunker is made? (By method of sample drying or by any other)?

    Дата публикации: 15.05.2014

    Calibration for the hopper and dispenser is performed using results of samples drying. The customer can independently change the calibration using results of his own measurements. Also there is the second way. It is possible to send you a calibration file prepared on the base of data received from you. This file should be installed on the moisture using supplied software and an ordinary PC.

    The moisture meter connects to PC via RS485, and an adapter allowing connection of RS485 line to the USB port can be supplied in the package.

    Information about calibration is also listed in the moisture meter operation manual.

  • How does heterogeneity of the material affect the sensor reading if I make a measurement of moisture? How does material size modulus affect the sensor reading?

    Дата публикации: 15.05.2014

    Due to the selected range volume of the material can be approximately represented as the sphere with a radius of about 25-30 cm. Therefore the heterogeneity within this volume is averaged. For accurate measurements size of material fractions should be approximately 10-20 times smaller than the wavelength. We use wavelength of about 1 m and if necessary it can be increased up to 7.5 m.

  • How flow and pressure changes affect the moisture meter?

    Дата публикации: 15.05.2014

    Pressure and flow of the material does not affect the measurement. Influence of the flow may occur due to cavitation effects on inhomogeneities within the sensor (narrowing, capacitance elements bottlenecks, etc). However, since cross section does not change along steaming direction and there are no capacitance elements in our sensor, such problem does not exist.

Desined and supported by Formatix Labs

Desined and supported by Formatix Labs

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Website is translated by Lingvo-Prof translation agency