In-Line Moisture Analyzer 1

[controlnovice]

I am interested in a recommendation for an In-Line Moisture Analyzer for rubber/plastic powder.

This is a manufacturing plant. The analyzer we currently have is an IR machine with a glass plate. The glass plate is frequently dirty, which gives us bad readings. Plus, the instrument drifts often. This was installed about 10 years ago.

Is there anything new out there for In-Line moisture analyzers for this type of service (rubber/plastic powder, coating problems, temperature around 100F, 0.5 - 1% moisture content)?

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This is normally the space where people post something insightful.

 

[sparky970]

We use a TDL (tunable diode laser) to measure moisture in CL2

 

[controlnovice]

Looks like the TDL is only for gas.

Our product is a solid (powder).

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This is normally the space where people post something insightful.

 

[JLSeagull]

I have done IR temperature in rubber crumbs but not moisture. My moisture applications are in liquid and gas using companies like Cosa, GE Sensors (Panametrics), Ametek (DuPont), etc. I used MSC (Moisture Systems Corp.) decades ago for something. that may be long gone. MSC is now Thermo Scientific. Poking around their site was not very successful.

http://www.thermo.com/com/cda/product/detail/0,1055,13804,00.html

Perhaps you have something like this sensor for moisture in crumb rubber:

http://www.processsensors.com/Applications/app_PDF/Crumb Rubber 2006.pdf

or perhaps one of these:

http://www.powderandbulk.com/analyzers/moisture.htm

Moisture in gas is easier and can still be a problem.

 

[katmar]

Controlnovice - the following is a message sent to me by an acquaintance. If you want to be put in contact with him contact me via my signature below.

I have some experience of inline measurements of moisture of a free flowing powder. In my case it was a solid bleach for detergents. Its moisture varied from about 7% to ~2%. Its bulk density was about 800g/l and its particle size was about 500 microns. After rejecting an IR device (drift, terrible calibration, influence of surrounding air moisture) I made a very simple measuring instrument on the basis of capacitance/resistance measurement with an AC source.

I constructed a sensor that was fixed in the bottom of a vibrating transportation trough. The sensor was easily removed for inspection or cleanning. I started testing my material with different ceramical sensors (Al2O3) but a much simpler version was finaly good enough. My first measuring instrument was a cheap hand held AVO meter, measuring capacitance at 800Hz. I started to measure the response (correlation) of capacitance to a change of moisture content. The curve was strictly nonlinear, something that was explained with a lot of literature backup.

The main problem was a good (immediate) reference analytical method and the problem of bulk density or particle size variation during the continuous sampling: you should provide somehow same bulk density flowing over the sensor; it does not need to be the exact bulk density of your product however.

My measurements were repeatable enough so that later we got a professional capacitance bridge that was still very cheap compared to sophisticated IR or neutron absorption analyzers.

In the production line there was a problem with people that did not inspect the sensor or take care to clean it but only complained that reading was false. I made a simple program that recognised dirty sensor or some other electrical malfunctions and made a warning. The system still works after many years.

As I have some spare sensoring cells I can send it to Controlnovice if he wishes to make some experiments. It should be mentioned that my cell was optimized for my material: the structure of the electrode layout is material and instrument dependant, while the penetration depth of the electrical field is a function of voltage and frequency of your AC source as well as a function of the electrical permitivity of your material (epsilon and epsilon') as well as its partical size and sphericity.


Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com