LaMotte Water Link Spin Touch CW Faq

FAQ

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Frequently Asked Questions (FAQ)

How does the Spin Touch® meter work?

The LaMotte Spin Touch® Photometer is a colorimeter that uses centrifugal fluidics photometry. This
just means that it spins a test disk, with prefilled reagents, to fill specific test cells, and then uses several
light sources to test the color changes in those cells. It runs all eight parameters at one time, delivering
fast results. The system allows for fast, reliable testing results using established colorimetric methods.

What cooling tower parameters are currently available?

Currently the Spin Touch® Cooling Tower Disks test pH, alkalinity, free and total chlorine, calcium and
total hardness, copper and iron. Tests for silica and phosphate are currently in development.

How does this test method compare to other available methods, such as drop count titrations?

While the Spin Touch® meter uses established colorimetric reagent test methods, like those used in a
color wheel or color block, it’s application within a disk is a little different. The meter introduces
reagents, pre-measured inside each cell, that provides the necessary test buffers and indicators. This
produces a color-change, which is measured using a photometer, where light absorption is measured
through the cell and compared to a curve. This is very similar to a digital colorimeter used in water
testing.

The multiple parameters and spinning disk present unique approaches to testing. However, the disk is
similar to other test methods like drop count titrations and colorimetric wheel tests. The test
procedures have potential interferences and limitations just like other tests. The tests have +/- 5-15%
accuracy and precision. This is similar other test methods. However, the specific interferences and
accuracies can be different to other methods, meaning when you compare results to drop count
titration, the results can be different. The Spin Touch® also is reliable, meaning that you will find
consistent results to help you measure and run a program.

The Spin Touch® results are not similar to what I am used to with other test methods.

You should not expect the Spin Touch® to perform exactly like other test methods. Each method has
unique chemistries, procedures, potential issues and interferences. It is important to understand how
the disk operates and potential issues. For example, in drop count titration, proper sample fill, how the
dropper bottle is held, bottle tip issues and certain interferences can greatly affect results in a way you
may not be aware of. The Spin Touch® similarly can be affected by proper disk handling and fill, and
potential interferences.

The Spin Touch® uses slightly different test procedures than you may be used to. For example, most
likely you have used a titration method to measure hardness. The Spin Touch® uses a colorimetric
method, and test interferences will be different from other methods you may be familiar.

AquaPhoenix Scientific – WaterLink Spin Touch® Guide 1

For example, the drop count titration method you are used to may be +/-20% in accuracy. Where the
Spin Touch® meter is also +/-15% accurate. This means you may see a range that differs from other
method’s results. Or a specific chemical may not interfere with one test, but interferes now with the
Spin Touch® meter. What is most important is continued repeatability, that the results are similar from
test to test. This allows you to test, measure and run a water treatment program.

What is the accuracy of the Spin Touch® meter tests?

The specific tests differ in accuracy, but typically have between 5-15% precision. This is a measure of
how close to the actual result the readings are. The meter is highly precise, meaning the tests are very
similar test to test. This is most important in testing water as it means you can apply a test
measurement program and respond to changes in results.

Like all tests, proper procedure is required for accurate and consistent results. This includes properly
filling the disk. The disk procedures, manual and video shows this technique.

What type of applications are best fit for the Spin Touch® meter?

The Spin Touch® meter requires a moderately sized photometer. The test results are fairly precise, but
can be limited at times in precision. The tests are highly accurate, meaning you can get consistent trends
over time. Finally, the disks are very easy to use. For these reasons, we feel the meter best fits end-user
applications for testing. For example, an end-user can apply the disks to make daily testing for a cooling
tower easy and affordable, ensuring consistent data for the water treater.

My results seem wrong, what can be causing this?

The number one reason for questionable results is the underfilling or overfilling of the Spin Touch® disk.
An underfilled disk particularly will dramatically change certain results, not properly filling the sample
cell on the disk. Be sure to follow the instructions for proper filling, filling the final cell to the top all the
way to the final fill line.

There are some common interferences that can affect the disk. The key issues are turbidity and free
iron. Turbid waters can present materials that block the channels in the disk, underfilling the cells. You
may need to filter the sample using filter paper and funnel to remove excess turbidity. This should not
affect wet chemistry tests.

Excess iron in the water, rusty water, can cause discoloration or blockage that affects results. Filtering
may help in these situations.

Finally, if the water is excessively colored, this can affect the Spin Touch® disk, like all colorimetric tests.

AquaPhoenix Scientific – WaterLink Spin Touch® Guide 2

What are the common interferences in cooling water with the Spin Disks?

In cooling waters, there are some common interferences that can affect specific tests. Iron, manganese
or zinc can affect the hardness test, as it can interfere with the test indicators. There are ways to adjust
the firmware to help account for this. Certain biocides in high levels can affect some tests, particularly
the alkalinity test. Quats and polyquats specifically can lead to these problems. Phosphates and
permanganate can affect iron readings.

My chlorine numbers appear to be off, what can be interfering with this?

The chlorine tests in the Spin Touch® use a standard DPD test method. These have common potential
interferences, including where excess chlorine above 15ppm can bleach the reagent and show a false
negative for chlorine. High level of salts and quats can affect readings.

My hardness numbers appear to be off, what can be interfering with this?

Metals (copper, iron, manganese) can interfere with the hardness test. Unlike titration tests, the disk
does not allow you to adjust indicators to account for this. There are some meter adjustments that can
help. However, it is important to understand the potential offset in readings, and then adjust final
results. The meter is highly accurate and repeatable, so trending becomes most important in a water
treatment program, as long as the inference is understood. Occasionally the Calcium hardness metal
bead can be stuck if the disk was overheated. Refer to the color guide for an example.

My alkalinity number does not appear correct, what can be interfering with this?

The disk will always have a color change for alkalinity. You can refer to the color guide for more
information. If the cell is colorless, there is an issue in the test procedure or fill. Finally, quats and
polyquats can interfere with the alkalinity reading.

AquaPhoenix Scientific – WaterLink Spin Touch® Guide 3