RUSSIAN SPANISH ENGLISH

 

Frequently Asked Questions

•    How does MoistScan® work?

•    How often does the MoistScan® require calibration?

•    How much does the MoistScan® cost?

•    How will I know if MoistScan® will work on my material?

•    I have heard that high and variable temperature affects microwaves. 
     The material I wish to measure is very hot. Will this be a problem?

•    Does MoistScan® work on conductive materials?

•    Over what moisture range will the MoistScan® work?

•    How accurate is the MoistScan®?

•    I wish to measure the moisture in several grades of material. Will the MoistScan® require a calibration for
      each grade?

•    What affect does changing bulk density have on the accuracy of the MoistScan®?

•    Does MoistScan® measure free, inherent or total moisture?

•    Does MoistScan® measure ice?

•    I have heard the online moisture analysers are very susceptible dust and variation in light. Is this the case
      with MoistScan®?

•    Will steam affect the accuracy of moisture analysers?

•    I have heard that some online moisture analysers use a radioactive source to measure mass flow rate. Is this
      the case with the MoistScan®?

•    Do the microwave sensors contact the material?

•    How is MoistScan® calibrated?

•    You state that the MoistScan® has a precision of 0.3% at 1 SD (application dependent). What do you
      exactly mean?

•    What things affect the accuracy of MoistScan®?

•    What is Near Field Analysis (NFA) and how does it work ?

•    Why use microwave moisture analysers?

•    What does a precision of 0.1% mean?

•    What does an accuracy of 0.5% at (1STD DEV) mean?

•    How many samples should be taken to produce a calibration with a high degree of confidence?

•    Are the moisture readings affected by relative humidity?

•    Our product has many colour variations, will this affect the results?

•    Will the temperature of our product adversely affect the moisture readings?

•    There is noticeable segregation of our product on the conveyor. Does this matter?

•    Our process is in close proximity to steam. Will the presence of the steam give false moisture readings?

•    What if the steam condensates on the Microwave antennas?

•    Previously we used NIR gauges that required regular cleaning of the lenses to remove dust accumulation.
      Does the MoistScan require such regular and time wasting maintenance?


•    How often will the MoistScan® need to be calibrated?

•    Will the microwaves affect the chemical balance or in any way alter the material it measures?

•    We have concerns with safety of using Microwaves that are unshielded.

•    The bed depth of our material will occasionally exceed the maximum bed depth, will our moisture readings
      be affected by these spikes in bed depths?

•    Does the MoistScan® measure “Free moisture” or “Total moisture”?

•    What inputs and outputs are provided by the MoistScan®?

•    How does the MoistScan® compare with Nucleonic Gauges?

•    I am sceptical that your depth measurement using ultrasonics compensates for bulk density.
      Can you explain how the ultrasonic depth sensor compensates for variations in bulk density?

•    How does MoistScan® differ from other online moisture meters?

•    How does presentation of the product to the MoistScan® affect accuracy?

•    What factors determine the accuracy that we can achieve?

•    How does the microwave process differ from Near Infra Red (NIR)?

•    Can you do batch processing operations?

 

Questions and Answers


Q.   How often does the MoistScan® require calibration?

A.   Whenever a change in material presentation that is sufficiently different from the original material or for
      maintenance purposes around every 12 months to ensure reliable readings.

 


Q.   How much does the MoistScan® cost?

A.   Update coming

 


Q.   How will I know if MoistScan® will work on my material?

A.   If after reading our list of successful installations you are unsure, just ask one of our engineers who can
      assess your application.


Q.   I have heard that high and variable temperature affects microwaves. 
        The material I wish to measure is very hot. Will this be a problem?

A.   Temperature compensation can be built into the moistscan to minimise the effects of high temperatures.

 

Q.   Does MoistScan® work on conductive materials?

A.   The Moistscan has proven itself on conductive materials, however it is best to check with one of our 
      engineers to ensure you are going to have the best product that suits your requirements. We may be able to
      assist with one of our NFA enabled Moistscan analysers if the material is highly conductive.

 


Q.   Over what moisture range will the MoistScan® work?

A.   0-90% moisture that is NON-CONDENSING

 


Q.   How accurate is the MoistScan®?

A.   The moistscan’s accuracy is typically as good as or better than lab results.

 


Q.   I wish to measure the moisture in several grades of material. Will the MoistScan® require a
        calibration for each grade?

A.   The Moistscan can be calibrated with multiple configurations to overcome the differences in grades.

 

Q.   What affect does changing bulk density have on the accuracy of the MoistScan®?

A.   Bulk density compensation is built into the Moistscan and as such changes in bulk density are not an issue.

 

Q.   Does MoistScan® measure free, inherent or total moisture?

A.   Moistscan measures TOTAL moisture. Free moisture is moisture that can theoretically be dried off the material
      by a drying process. Inherent moisture is moisture that is bound within the material being measured.
      TOTAL is the combination of both.


Q.   Does MoistScan® measure ice?

A.   No, microwave only measures the moisture in liquid phase.


Q.   I have heard the online moisture analysers are very susceptible dust and variation in light. Is this
       the case with MoistScan®?

A.   The moistscan uses a patented transmission technique that is unaffected by light and dust.

 

Q.   Will steam affect the accuracy of moisture analysers?

A.   No. steam only have negligible affect on the accuracy of the MoistScan.

 

Q.   I have heard that some online moisture analysers use a radioactive source to measure mass flow
       rate. Is this the case with the MoistScan®?

A.   Unlike some competitors, Moistscan does not employ the use of any radioactive materials to achieve its
      results

 

Q.   Do the microwave sensors contact the material?

A.   Moistscan uses a NON-CONTACT transmission technique.

 


Q.   How is MoistScan® calibrated?

A.   By obtaining a reference set of samples from a lab for the material to be analysed

 


Q.   You state that the MoistScan® has a precision of 0.3% at 1 SD (application dependent). What do
        you exactly mean?

A.   The precision is based on the type of material to be analysed and how amenable it is to using a microwave
      technique. Some materials can result in 0.1 precision.


Q.   What things affect the accuracy of MoistScan®?

A.   The reliability of original lab samples, the presentation of the material (if inconsistent) and some 
      environmental factors. All these factors can be overcome by providing as much information as possible so our
      engineers can find a suitable installation point where theses factors can be reduced or eliminated.


Q    What is Near Field Analysis (NFA) and how does it work ?

A.   Magnetite concentrate and magnetite ore have proved to be difficult applications for the standard
      MoistScan® transmission technology. This is chiefly due to the magnetic nature or magnetic permeability
      of the product. The magnetic permeability is the degree of magnetization of a material in response to a
      magnetic field.

      Put simply, the microwave transmission signal is largely affected by the water within the Ore/Concentrate
      BUT unfortunately also affected by the magnetic permeability of the product. This is a problem because we
      cannot distinguish the moisture changes from the magnetic permeability changes.

      Recently Callidan has developed an analyser which will overcome these difficulties. We call it NFA
      (Near Field Analysis) but it is simply a direct measure of the magnetic susceptibility and microwave
      response (via reflection) of the material. It is called “Near Field Analysis” because the analysis zone
      will only penetrate the lower portion of the product upon the conveyor and NOT all the product like our
      previous transmission technique.

 

Q.   Why use microwave moisture analysers?

A.     Consistency and better accuracy over other types of methods. eg: NIR (near infra red), microwave
        technology is safe and reliable, unaffected by material presentation & colour variations, etc.
        For full details click here

 

Q.    What does a precision of 0.1% mean?

A.    Precision is a gauge of the deviation within a set of measurements. In this case, it is the repeatability
       of moisture content measurement. It is expressed as the standard deviation of a number of measurements
       of the same sample.

Q.    What does an accuracy of 0.5% at (1STD DEV) mean?

A.    Accuracy is a gauge of the deviation between a measurement and the value of the property being
       measured. In this case, it is the deviation between the MoistScan® results and the laboratory results for
       a set of samples. It is expressed as the standard deviation of the differences between analyser and
       laboratory results.

Q.    How many samples should be taken to produce a calibration with a high degree of confidence?

A.    The more samples taken, the more confidence placed in the calibration. Many statistical measures have
       little confidence below sets of less than 30 samples. If taking 30 samples is not feasible, then as many
       samples as can be taken. To increase the level of confidence from a set of samples, they should be
       analysed more than once.


Q.    Are the moisture readings affected by relative humidity?

A.    No, non condensing relative humidity does not affect the moisture readings.

 

Q.    Our product has many colour variations, will this affect the results?

A.    No, unlike the majority of NIR systems, the MoistScan® is unaffected by colour variations.

 

Q.    Will the temperature of our product adversely affect the moisture readings?

A.    Under normal circumstances the answer would be no. However, products with high temperatures
       (above 60º C/140º F) can be compensated with the use of the optional temperature sensor unit.

 

 

Q.    There is noticeable segregation of our product on the conveyor. Does this matter?

A.    The microwave technique penetrates through all the product material on the conveyor, so there is no
       adverse effects of product segregation. This segregation may have an affect how representative samples
       taken from the conveyor are.

 

Q.    Our process is in close proximity to steam. Will the presence of the steam give false moisture readings?

A.    No, steam has a very low dielectric constant compared to liquid water. As the MoistScan® uses a
       patented process for dielectric discrimination, the moisture readings will not be affected.

 

Q.    What if the steam condensates on the Microwave antennas?

A.    Using a compressed air stream to remove condensation is one option or alternatively install the analyser
       at another location away from the steam source.


Q.    Previously we used NIR gauges that required regular cleaning of the lenses to remove dust
        accumulation. Does the MoistScan require such regular and time wasting maintenance?

A.    No, the microwave antenna of the MoistScan® are usually unaffected by surface dust. They are also
       robust enough to withstand normal wash down procedures that are common on many processes.

 

Q.    How often will the MoistScan® need to be calibrated?

A.    Under normal operating conditions, the MoistScan® should not require re-calibration unless product
       presentation is significantly altered. However Callidan do suggest some check samples be taken every
       three months to confirm accuracy.


Q.    Will the microwaves affect the chemical balance or in any way alter the material it measures?

A.    No, The microwave power emitted from the lower antenna is approximately 10 mW (10 dBm), which is
       significantly less power than most mobile (cellular) phones.

 

Q.    We have concerns with safety of using Microwaves that are unshielded.

A.    The MoistScan® MA-500 On-Belt Moisture Analyser is designed to use low level non-ionizing microwave
       radiation. The microwave power emitted from the MOISTSCAN MA-500 is less than 10 mW (10 dBm).
       This complies with AS/NZS 4268 which specifies the maximum Equivalent Isotropically Radiated Power
       (EIRP) for short range radio equipment. Furthermore, this radiation level exists directly between the two
       antennas, which in almost all cases is inaccessible due to the conveyor belt. Microwave radiation further
       than 1 m from the analyser is virtually undetectable.

 

Q.    The bed depth of our material will occasionally exceed the maximum bed depth, will our moisture
         readings be affected by these spikes in bed depths?

 A.     Using the ultrasonic depth sensor on the MoistScan®  the analyser can be programmed to ignore
        bed depths that exceed the maximum bed depth for the product. The unit will automatically re-commence
        analysing once the bed depth is back within the normal operating range. This answer also applies to
        bed depths that fall below a pre-programmed minimum depth.

 

Q.     Does the MoistScan® measure “Free moisture” or “Total moisture”?

A.     The MoistScan® measures free moisture. Inherent or crystallised moisture is not measured. Callidan are
        currently investigating techniques in measuring inherent moisture. ASK US!

 

Q.     What inputs and outputs are provided by the MoistScan®?

A.     The MoistScan® is provided as standard with these outputs:
        2 x 4-20mA
        2 x discrete digital inputs.
        Modbus over RS-232 (ASCII)
        Modbus over RS-485/Ethernet (optional)

 

Q.     How does the MoistScan® compare with Nucleonic Gauges?

A.     The MoistScan® has proven itself to be reliable, repeatable and much more cost effective than any
        similar Nucleonic based moisture analysers. Other advantages are: No radioactive sources in the
        MoistScan®, which means no red tape associated with getting radioactive sources government approved
        and ultimately it is a safer more environmentally friendly gauge.


Q.     I am skeptical that your depth measurement using ultrasonic compensates for bulk density.
          Can you explain how the ultrasonic depth sensor compensates for variations in bulk density?

A.     The ultrasonic depth sensor is satisfactory for most applications that involve moderate variations in
        bulk density. It is, however, limited in applications that have very dense material combined with large
        variations in bulk density. In these applications we take an input from a weightometer or similar mass
        throughput sensor to compensate for the density effects.

 

Q.     How does MoistScan® differ from other online moisture meters?

A.     The MoistScan® employs a patented technique that differentiates it from its competitors. Using a
        combination of attenuation/phase shift of the microwave signal and dielectric discrimination
        techniques, the MoistScan® will provide the end user with consistently reliable results.

EXAMPLE:
        Fine coal typically has a dielectric constant of between 2 to 4 compared to the dielectric constant
        of water of 80.4. The variation of water within the coal results in a large variation in the combined
        dielectric constant which may then be measured by monitoring the change in the microwave signal. Both
        the change in velocity (phase shift) and the change in power (attenuation) of the received microwave
        signal are affected by the change in the dielectric constant of the analysed material. The microwave
        measurement is affected mainly by the excitation of free moisture molecules rather than many other types
        of materials, due to the extremely high dielectric constant of water.


Q.     How does presentation of the product to the MoistScan® affect accuracy?

A.     Ideally the presentation of the material should be uniform; however slight changes in presentation should
        not pose any problems with maintaining reliable results. If material upon a conveyor is not centred
        correctly, or is badly profiled, then a leveler bar could be installed to improve the material profile.

 

Q.     What factors determine the accuracy that we can achieve?

A.     Factors that influence highly accurate results are: Minimal spread of moisture range. (The tighter the range
        the more accurate the instrument will be), even material presentation on the transport medium,
        representative sampling, careful handling of samples and prompt analysis. The analysis procedure should
        consume all of the sample.

 

Q.     How does the microwave process differ from Near Infra Red (NIR)?

A.     The microwave principle employed by the MoistScan® is a full penetration technique which means the
        product is fully scanned for moisture content as opposed to NIR, which is basically a surface technique
        using an infra red light beam. The results of a NIR gauge is adversely affected by colour variations, ambient
        lighting, and presence of dust and temperature variations. The MoistScan® is unaffected by any of
        these anomalies, thus the MoistScan® will give a more accurate indication of the free moisture within the
        product.

 

Q.     Can you do batch processing operations?

A.     Yes, by using multiple calibrations in the MoistScan® (up to 4 separate calibrations can be utilised by
        default with the option of 50 calibrations in total) it is as easy as switching a remote calibration switch
        either from the control room or on the MoistScan’s control panel for different products.



 

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