SInar Moisture Analyzer Support, including custom calibrations

Sinar Technology specializes in manufacturing scientific instrumentation, used primarily for the evaluation of specific properties in agricultural commodities, like moisture determination. Because moisture determiination plays such an important role in the quality, shelf life, and transportation costs of such goods, the Sinar Family of moisture analyzers have become internationally recognized as the workhorse of quick and accurate moisture determination.

Although the technology and logic differs slightly with the different types of Sinar Moisture Analyzers, they all do essentially the same thing, the primary difference being how the sample comes in to contact with the sensors on the instrument, which is based on the samples size and density characteristics. Capacitance based analyzers generally have to collect information on a samples mass, density, chemical composition, and temperature, to be able to provide an

accurate moisture reading. For hygroscopic, free flowing, sample types, the speed, accuracy,

and relative low cost of capacitance type analyzers, make them an increasingly popular choice.

FIRST STEP

The first step is to determine if the commodity being tested is compatible with

a capacitance based analyzer.As long as the commodity is hygroscopic (picks up or gives off moisture readily) , free flowing, and of uniform density and chemical composition, it should be suitable. Grains, seeds, feeds, and even some plastic products are examples of such commodities. The easiest way to tell if a material is suitable, is to put the same amount in the cell repeatedly, and check for consistent readings.

SECOND STEP

Next a collection of samples with known and varying moisture contents, needs to be obtained. Place each sample in the Sinar, and obtain a raw data reading (Referred to as Code 0 Reading). Then the collection of raw data readings, and corresponding moisture percentage values, are entered in to

the instruments software (MNET) via a computer. (See right)

TIPS

A sample can be stored briefly in small jar, inside an air tight container like this cigar jar (FIG 1), with water at the base to elevate a samples moisture content, or alternatively dehydrated to create a sample with lower moisture. Using the included coarse sieves, and some other components from the manual Particle sizer, fitted with PVC, a ball valve, and some hose clamps, a crude but effective fluid bed dryer (FIG 2) can be constructed using the low setting on a standard hair dryer to provide the heated air flow. Very advanced fluid bed dryers (FIG 3) are now able to dry materials while simultaneously plotting a moisture curve. Fluid bed dryers operate by suspending the particles in a heated and agitated air pattern, which allows for uniform drying.

FIG 1 FIG 2 FIG 3

While working with hygroscopic samples try to store them at room temperature,

in sealed glass jars with as little head space as possible.

When obtaining moisture values for the different samples, either by oven, moisture balance, or Karl Fischer,

be sure to use a representative sample. The larger the sample, (within reason) the better the results will be.

Example: You can't really take one raisin out of a box, and expect it to be representative of the whole box. Moisture levels vary within a sample to some extent. The moisture in the middle of a pile is likely to be higher than at the top.

If using a loss on drying type of reference method, try to ensure uniform drying by preparing the sample. Nuts and grains can be ground.

Before starting, be sure to check with us if we already have a calibration for your commodity.

INSTRUMENT CALIBRATION

The available support document download gives detailed instructions on how to perform a hardware calibration on the instrument. Newer units have a Cal/Auto Button which when pressed will give a value that tells whether or not the instrument needs to be calibrated. Anything other than an A000, generally indicates the need to perform a hardware calibration.

Be sure to follow the instructions relative to your particular instrument, including whether it is a newer version or an older one. You will need a calibration sample which consists of a 180 gram sample of wheat, with a certified Code 0 Value.

This will help ensure the balance, and sensing components are reading correctly. You will also need a small digital

temperature probe to ensure the temperature sensor in the instrument (Small black metal bridge inside the cell.) is reading properly.Lastly, you should have an RS 232 to Serial Port Cable to connect to a computer.(A Serial Port to USB adapter is available) so that you can upload your moisture curve set to file for safe keeping. With the available MNET Software Package you can also transfer moisture curves to other Sinar Instruments, or create new ones.

PROCEDURE

Click the MNET Icon on the left. When the box opens, select Save to Desktop. Next select Open.

You will have opened the zipped folder, and now see the folder MNET 8.0 BLANK DIRECTORY. Double click the

MNET Folder to enter the MNET Program, or the F4 Folder to enter the F4 Program.

NOTE: Mnet Software is a DOS Based Program, that is used to access the programming functions of the Sinar Moisture Analyzer. As with many DOS Based Scientific Programs, there are compatibility issues with Windows Versions higher than 98.The F4 Software was developed as a means of fixing some of the communication problems that resulted from the newer versions of Windows. It is used primarily to download and upload calibration curves between the instrument and the computer.To utilize either software, it is recommended to use a computers serial port connection via the supplied RS 232 to serial port cable. A serial port to USB Converter Cable is available, if a serial port is unavailable.Not all serial port to USB Converters work.

Double click the MNET folder, then the MNET Executable File, then EXTRACT ALL, then NEXT, NEXT, YES TO ALL, and FINISH. Now you'll see the MNET Folder in front of you.

NOTE: This is where the working MNET File is located. It would be best to save this folder to a memory stick, so that the location of a calibration file will be easily found. You'll see why this is handy later, but basically it's easier to type F:/MNET, than something like C:\Documents and Settings\USER\Desktop\MNET_8.0_BLANK_DIRECTORY\MNET 8.0 BLANK DIRECTORY\MNET

Open it, and double click the MNET Executable File. Then click RUN,. When the program opens, type lavender for the password. Now you are in the MNET Program. Select F1 through F8 for the various menus, and H for help in each menu. There are detailed instructions for MNET and F4 inside the folder as well. To enter the data, select F1.

NOTE: The curve directory F7 and curve set directory F8, store various moisture curves and sets of curves. Moisture curves are stored in F7, and sets of up to 25 moisture curves, are stored in F8. A curve set is what is loaded on to the instrument. Example: The standard curve set for coffee includes a calibration for dried cherry, green, parchment, roasted, and ground coarse,medium,and fine. When the curves are downloaded in to the AP 6060 which has seven visible channels, the curves populate the seven channel buttons on the instrument. There is a library of approximately 1,000 calibration curves available currently. Any number of them can be sent as a file, and uploaded in to the directory, and subsequently be downloaded in to the instrument.Some of the curves are of a proprietary nature, but most are of a generic origin, and may be utilized.

From the F7 (Curve Directory ) Screen , select an open curve slot. Then from the F1 Screen, type C ,and enter the curve number, then hit enter. Then hit N to name the curve, and hit enter again. Now the values can be entered.

Once all of the available values are entered (Up to 32), the moisture curve is ready. Press U to update the file, and register it in the curve directory. Repeat this procedure for every moisture curve you decide to create.

NOTE: The more data points you have the more accurate the moisture curve. Before entering the data in to MNET, it sometimes helps to put the values in to an ExCel File, with two columns.Then by using the chart function in ExCel

you can create an X,Y Chart.This helps in

editing out stray data points, and in forecasting the curve out past known values.Then by applying the curve formula to the X Values, a new set of data points reflecting the ExCel Curve will be available for entry in to MNET.

Now select F8 and choose an open slot in the curve set directory. Choose a curve set below 900. 900 Series are used for temporary assignments when importing curves. Input the curve number in the F4 Screen, and press C to enter curve numbers one by one, in to a set. Then hit X to export the curve set to a named file. The file will now be visible in the MNET Folder, and you can close MNET out. To download the curve set to a machine, you can either follow the instructions in MNET, or with newer machines, utilize the F4 Software to download the curve set. In order to do this, you will need to drag the file in to the F4 Folder.

. CREATING SAMPLE MOISTURE CURVES FOR CAPACITANCE ANALYZERS

The primary or reference method by which moisture is generally determined, is known as loss on drying, or gravimetric's. A sample is weighed, and then placed in an oven at a very low temperature, over a fairly long period of time (Sometimes as much as 24 hours), to help ensure that volatiles (oils and other evaporative compounds) are not driven off along with the water.

After repeated heating and weighing, the rate of evaporation will change, and slow down substantially, as the critical moisture point is reached. It should be noted, that it is the residual or surface (chemically unbound) moisture that is generally being measured here. The sample is then weighed, and the result subtracted from the original weight, giving the moisture as a percentage of the total weight.

In a busy manufacturing environment, this process quickly becomes cumbersome. Moisture balances (Thermogravimetrics) can generally produce similar results, in a reduced time frame, but also experience the same concerns with regards to volatiles. (Many moisture balances now have the capability to set the temperature.) T hey are programmed to stop heating the sample when the rate of drying slows beyond a preset point, which may leave out some of the moisture content.

Sinar Instruments uses an indirect method of determining moisture. Most capacitance based analyzers emit some type of electrical signal, ie...radio frequency, X-ray converted to electrical, or other, and it's how that electrical signal reacts with the available moisture in the sample that provides the reading. The popularity of these instruments is based on their ability to achieve useable accuracy in a substantially reduced time frame, in the case of Sinar, usually around six seconds

As with most indirect methods, although the instrument reads the reaction of the electrical signal as it comes in to contact with water, it doesn't have the intuition to convert the reading in to a useable moisture percentage reading. So we have to do it.