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DA-130N portable density meter General Maintenance Guidelines

By Hank Levi on Tue, Jul 31, 2018 @ 03:18 PM

This is a quick guide to getting started and running your first test.  We thought it would be helpful for those getting started and checking their first calibration before running tests with actual samples.  We will also continue to explore and share more information about calibration options, general maintenance, and data export methods using the DA-130N portable density meter.

O.K.  Let's install three 'AAA' batteries to get started.installing the batteries.png

And then attach the sampling nozzle.  attaching the sample nozzle.png


A few words about precautions when taking test measurements.

measurement precautions.png

When measuring a sample make sure to hold the instrument so that the sampling nozzle is vertical to the ground.  When laying down the instrument between or after measurements make sure to drain the remaining sample from the built-in syring (the built-in syringe is located inside the meter right above the sampling nozzle).

 builtinsryring2.png


Now let's run a preliminary test using water.  

Leave the temperature unit (Celsius), measurement unit (g/cm3) and mode (Field) as initial values. Sample pure water using the built-in syringe.  After the measurement cell is filled with sample liquid make sure there are no air bubbles in the cell.  If no air bubbles are visible then let's proceed.
 
Example procedure for running first test.
screen view at current temp before stablized.png
The display changes as above and after confirming it is in the automatic stability sense mode. Press [Meas.] key.  When the displayed density is stabalized the value will automatically change reversed as below.  Read the data at this point as well as the temperature degree.
screen changes reverse when stabalized.png
Look up to the pure water density table (appendix 1 in the manual).  If the results agree within +-0.001g/cm3, you can proceed to making your sample measurements!
 
densityofpurewater.png
 
Note: If the results are not within the acceptable range then the measuring cell requires calibration.
 

Calibration of the measuring cell using pure water

calibrationofmesaruingcell.png

Set calibration mode to OFF.  Press the [esc] key 2 times to return to the main menu.  Sample pure water making sure no air bubbles are visible.  The measuring cell with pure water can be calibrated automatically with the key entries as follows:  Press [cal.] key for more than 2 seconds to show CALIB(Water) (inversed colo on the display) showing calibration with pure water in progress.

Screen Shot 2017-05-01 at 1.17.26 PM.png

After calibration is over the deviation from the theoretical value will be shown so that you can check if the calibration has been successfully completed.

Screen Shot 2017-05-01 at 1.17.33 PM.png

Note: if after attempting re-calibration of the measuring cell and results are still not within specifications it is possible the measuring cell itself is contaminated.  In this case ensure to carefully clean the measuring cell and then re-calibrate again.

Note 1: You can also calibrate with a standard liquid that has a known density.  Sometimes calibrating with a liquid that has a similar density to your test samples will help improve precision.

Note 2: You can also calibrate with air.


General maintenance - How to clean and dry the measuring cell and replace the built-in syringe

Step 1: Clean the measuring cell

You can thoroughly clean the measuring cell with just pure water.  You can also improve the cleaning of the measuring cell by using Ethyl Alcohol.  Ethyl Alcohol gets rid of dirt that cannot be removed with pure water and also reduces the amount of time to dry the measuring cell.

  • Estimate 5 to 10 minutes for the measuring cell to dry after cleaning with pure water
  • Estimate 3 to 5 minutes for the measuring cell to dry after cleaning with Ethyl Alcoho

Step 2: Purge air to dry the cell thoroughly and completely 

option using an air pump:

commercial pump to dry the cell.png

 

OR use the optional manual pump to dry the cell:

optional manual pump to dry the cell.png

When using the optional manual pump to dry the cell make sure to clean the cell first and then press the sample discharging lever all the way down, and push the sample intake lever upward to lock it.  With the adapter for the syringe attached connect the kit as illustrated above and feed air forcefully using the manual bulb.

How to replace the built-in syringe.Maitenance how to replace the built-in syringe.png

  • Press down the sample discharging lever all the way and remove the syringe cover by pulling it toward you as illustrated.
  • Turn the syringe 45degrees counter clockwise to release it from the o-ring.
  • Slightly pull the sample drain-out lever toward you to pull out the syringe from the o-ring.
  • Remove the syringe from the drain rack and replace it with a new one.
  • Pull down the drain rack and insert the o-ring  and turn it back clockwise until it stops.
  • Place the syringe cover back on the unit.

 

Data Processing and Storage

The maximum number of data which can be stored in the DA-130N memory is 1,100 samples.  Data can be set to be saved automatically or manually after each test.  You can recall stored measurement data on the DA-130N display again or output the data to a printer or PC.

Exporting data to a PC via Infrared:

Data export via infrared to PC.png

Exporting data to a PC via RS-232

Data export using RS-232 to PC.png

Sending data to a printer:

Exporting data to a printer via RS-232.png

Example printout of data:

Printout Sample for the DA-130N.png

We hope this information about this particula density meter is helpful.  If you need other capabilities beyond a traditional portable density meters refer to other bench top density meter models for increased accuracy. 

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Q&A: AT-710 Burette piston won't move

By Hank Levi on Tue, Jun 19, 2018 @ 03:36 PM

Sometimes pressing a button and hearing a beep just drives you crazy.  We know.  Below we received some video of a problem where the operator could not move the piston burette up or down on their automatic titrator.  We decided to replicate the problem and then show how to take corrective action.  We hope you find the video informative even though it is raw footage.  Send us your questions too.  Video, audio, pictures, etc.  We can use any format.

 
 

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What happened to Hydranal Karl Fischer Reagents?

By Hank Levi on Sun, Nov 05, 2017 @ 08:12 PM

There has been some confusion in the market place when it comes to purchasing Karl Fischer reagents and water standards.  Some of you who have traditionally ordered the Hydranal brand from Sigma Aldrich (and it's channel partners and dealers) are discovering now that the Karl Fischer reagents and waters standards are slightly different - If you order them from Sigma Aldrich.  The names on the bottles are kind of the same, but not exactly.

milliporesigmalogo.png

Some background - what happened to Sigma Aldrich

As many people know Sigma Aldrich for many years handled the Hydranal line of Karl Fischer Reagents and water standards.  Recently (within the past year and a half or so), a company called EMD who controls the other Karl Fisher reagent line called Aquastar purchased Sigma Aldrich.  As a result of this transaction Sigma Aldrich is now part of another company and is referred to as MilliporeSigma.The Sigma Alrdrich you used to know no longer provides the Hydranal brand but intstead now offers the Aquastar line of Karl Fischer Reagents and water standards.

What happened to the Hydranal brand of Karl Fischer reagents?

honeywelllogo.jpgA well-known company called Honeywell purchased and now controls the Hydranal line of Karl Fischer Reagents.  You can still order Hydranal brand coulometric Karl Fischer reagents and volumetric Karl Fischer reagents via Honeywell and it's channel partners and distributors.

What does this mean to you and how might this effect you?

As you can imagine this has triggered a lot of phone calls with questions from end-users to purchasing agents with questions like:

  • Are these reagents the same?
  • Can I use these reagents interchangeably?
  • What are the differences?
  • Hydranal vs. Aquastar?

Here's what we know

As a manufacturer and distributor of coulometric Karl Fischer titrators and volumetric Karl Fischer titrators for many years, we have worked with both the Aquastar and Hydranal brands extensively.  We are not here to tell you one is better than the other.  We can tell you that different model Karl Fischer titrators seem to work differently depending on the brand of Karl Fischer reagent used.  It might simply be an operators familiarity with working with one brand vs. the other or it might be because a specific application just works better with a certain Karl Fischer reagent.  

-While the design is that either of these brands should work we find subtle differences in chemistry-  

Are there any real key chemical differences between Hydranal and Aquastar?

To be fair we have not reached out to Aquastar for their perspective yet (we will - and update this post).  From the Hydranal technical center we have obtained some information about what they see as strengths in the Hydranal brand and some differences with the Aquastar brand.  Here are a few notable points:

1. Different performance.  Yes they do perform differently.

2. Different solvents are used.  Example:  Aquastar Combititrant is a copy of the old version of Hydranal Composite 5 where there was no 2-Methylimidazole.  Without 2-Methylimidazole, you can have reagent crystalization and stability issues.

3. Co-solvents are optimized in Hydranal.  Too much Chloroform can mess up the stoichiometry

4. Hydranal coulometric reagents are more unique

  • Hydranal has more buffering capacity
  • Larger volume of samples than Aquastar

5. Hydranal is very precise, convenient and consistent

As mentioned above we hope to get some additional information on the Aquastar line so we can share with you their strengths and differences.  In the meantime we hope this information has been helpful.

If you have any questions or would like to compare the reagents you currently use with the "other" brand just let us know.  We can provide a cross reference for all of the Karl Fischer reagents by brand and product.

Learn More

As always, we hope this information is helpful.

 


 



 

 

 

 

 

 

 

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Using the DA-130N portable density meter for the first time

By Hank Levi on Mon, May 15, 2017 @ 03:29 PM

This is a quick guide to getting started and running your first test.  We thought it would be helpful for those getting started and checking their first calibration before running tests with actual samples.  We will also continue to explore and share more information about calibration options, general maintenance, and data export methods using the DA-130N portable density meter in future posts.

First, lets review and identify the parts of the DA-130N Portable Density Meter:

Front view of the DA-130N.png

 

Side view of the DA-130N.png

 

Rear view of the DA-130N.png

Display Window.png

 

O.K.  Now let's get started and install three 'AAA' batteries...installing the batteries.png

...And then attach the sampling nozzle.  attaching the sample nozzle.png


A few words about precautions when taking test measurements.

measurement precautions.png

When measuring a sample make sure to hold the instrument so that the sampling nozzle is vertical to the ground.  When laying down the instrument between or after measurements make sure to drain the remaining sample from the built-in syring (the built-in syringe is located inside the meter right above the sampling nozzle).

 builtinsryring2.pngMaintenance - replacing the built-in syringe.png


Now let's run a preliminary test using water.  

Leave the temperature unit (Celsius), measurement unit (g/cm3) and mode (Field) as initial values. Sample pure water using the built-in syringe.  when using the built-in syringe to introduce the sample.png
 
  1. Make sure the sample discharging lever is pushed down to the bottom.
  2. If not, slowly push it down with your thumb.
  3. Dip the sampling nozzle in the sample liquid.
  4. Slowly pull the sampling lever with the forefinger. When the cell is filled with sample, release your finger.
 
 
 
 
After the measurement cell is filled with sample liquid make sure there are no air bubbles in the cell.  If no air bubbles are visible then let's proceed.
 
Example procedure for running first test.
screen view at current temp before stablized.png
The display changes as above and after confirming it is in the automatic stability sense mode. Press [Meas.] key.  When the displayed density is stabalized the value will automatically change reversed as below.  Read the data at this point as well as the temperature degree.
screen changes reverse when stabalized.png
Look up to the pure water density table (appendix 1 in the manual).  If the results agree within +-0.001g/cm3, you can proceed to making your sample measurements!
 
densityofpurewater.png
 
Note: If the results are not within the acceptable range then the measuring cell requires calibration.
 

Calibration of the measuring cell using pure water

calibrationofmesaruingcell.png

Set calibration mode to OFF.  Press the [esc] key 2 times to return to the main menu.  Sample pure water making sure no air bubbles are visible.  The measuring cell with pure water can be calibrated automatically with the key entries as follows:  Press [cal.] key for more than 2 seconds to show CALIB(Water) (inversed colo on the display) showing calibration with pure water in progress.

Screen Shot 2017-05-01 at 1.17.26 PM.png

After calibration is over the deviation from the theoretical value will be shown so that you can check if the calibration has been successfully completed.

Screen Shot 2017-05-01 at 1.17.33 PM.png

Note: if after attempting re-calibration of the measuring cell and results are still not within specifications it is possible the measuring cell itself is contaminated.  In this case ensure to carefully clean the measuring cell and then re-calibrate again.

Note 1: You can also calibrate with a standard liquid that has a known density.  Sometimes calibrating with a liquid that has a similar density to your test samples will help improve precision.

Note 2: You can also calibrate with air.


Some other useful things to know when working with different types of samples:

For more viscous samples over 2,000mPa.s it's a good idea to use the optional syringe adapter set. Almost any commerciall available syringe (plastic works great) will work.  You just need to order the female adapter to make it work (Adapter part number is 12-04428-02)

Sample introduction via Syringe Option.png

When working with samples under 2,000mPa.s of viscosity but where samples contain particles or grains that may crystallize when dry we suggest you use the supplied bellows pump (swap out the built-in syringe for this). 

Maitenance how to replace the built-in syringe.png

 

We hope this information has been helpful!

Get more DA-130N Portable Density Meter Information

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Regular Bostwick Consistometer vs. Long Bostwick Consistometer

By Hank Levi on Thu, Apr 27, 2017 @ 01:22 PM

Many of us have used the CSC Bostwick Bostwick Consistometer.pngConsistometer and are familiar with it's operation.  Pressing down the gate and loading the trigger is step one.  Pouring in your sample and scraping off the top to a clean and even surface is important to getting repeatable results.  With a stopwatch in one hand, "popping" the trigger and letting the sample flow out and down the trough comes next.  Some tests are designed to see how far a sample will flow in say, 10 seconds.  Another testing approach might be to time the movement of the sample until it reaches a pre-determined point (bostwick).  If you have ever noticed in the bottom of the tray there are lines with numbers ranging from 0 to 24 (you really can't see a number 24 because the tray stops exactly at what would be 24).  Over the years these lines with numbers have affectionatly become to be known as "bostwicks". 

Most recently we have had requests to extend the length of the Bostwick Consistometer to accommodate samples that require more time and distance.  Not every sample flows the same way so this seemed like a good idea.  So to meet these needs we have now just started to offer a longer version of the Bostwick Consistometer!  Don't worry we still have the regular length Bostwick Consistometer available.

Bostwick Consistometers.jpg

  • The long version of the Bostwick Consistometer (part# 24925-000L) now extends from 0 to 32.  
  • The regular length Bostwick Consistometer (part#  24925-000) has a range of 0 to 24.  

Consistometers

 

 

 

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What is water activity?

By Hank Levi on Mon, Nov 14, 2016 @ 03:16 PM

There is sometimes confusion about water activity and how it relates to water content.  Water content is how much.  Water activity (aw) tells us about the energy of the water.  Both are measurable.  

Water Content

We know a lot about water content and how to measure it using various popular methods including loss on drying, Karl Fischer titration, capacitance and more.  Water content is typically expressed in % or Parts Per Million (PPM).

Water Activity

Water Activity is the amount of unbound water in a sample.  Water that is not bound to the ingredients themselves can be used by unwanted microorganisms which could lead to one of the contributing factors for food spoilage.  Water activity is a vaporpressure.pngthermodynamic measure of water expressed as the vapor pressure of water in a sample divided by vapor pressure of pure water at a given temperature.  

Water Activity is based on a scale from 0.0 to 1.0 

WaterActivityScale.png

The more unbound water we have the more likelihood we have for microbial spoilage. Water Activity (aw) Meters measure the unbound water vapor pressures to determine microbial spoilage, chemical and physical stability. 

wateractivityscale2.png

Well documented and scientifically established guidelines that are also supported by FDA regulations outline these thresholds of microbial limits using a water activity (aw) range or scale.  This water activity (aw) range provides the lowest rating for inhibition of microorganism and other degradative chemical and physical reactions that effect shelf life in foods (see chart below).  

                                     Get more Water Activity information


Water Activity & Growth of Microorganisms in Food

Range of aw Microorganisms generally inhibited by lowest aw in the range Foods generally with this range
1.00-0.95 Pseudomonas,Escherichia,Proteus,Shigella,Klebsiella,Bacillus,Clostridium perfringens, some yeasts Highly perishable foods and canned fruits, vegetables, meat, fish, milk, and beverages
0.95-0.91 Salmonella, Salmonella, Vibrio parahaemolyticus, C. botulinum, Serratia, Lactobacillus, Pediococcus, some molds, yeasts (Rhodotorula, Pichia) Some cheeses (Cheddar, Swiss,Muenster, Provolone), cured meat (ham), bread, tortillas
0.91-0.87 Many yeasts (Candida, Torulopsis, Hansenula), Micrococcus Fermented sausage (salami),
sponge cakes, dry cheeses,
margarine
0.87-0.80 Most molds (mycotoxigenic penicillia), Staphyloccocus aureus, most Saccharomyces (bailii) spp., Debaryomyces Most fruit juice concentrates,
sweetened condensed milk,
syrups, jams, jellies, soft pet food
0.80-0.75 Most halophilic bacteria, mycotoxigenic aspergilli Marmalade, marzipan, glacé fruits, beef jerky
0.75-0.65 Xerophilic molds (Aspergillus chevalieri, A. candidus, Wallemia sebi), Saccharomyces bisporus Molasses, raw cane sugar, some dried fruits, nuts, snack bars, snack cakes
0.65-0.60 Osmophilic yeasts (Saccharomyces rouxii), few molds (Aspergillus echinulatus, Monascus bisporus) Dried fruits containing 15-20% moisture; some toffees and caramels; honey, candies
0.60-0.50 No microbial proliferation Dry pasta, spices, rice, confections, wheat
0.50-0.40 No microbial proliferation Whole egg powder, chewing
gum, flour, dry beans
0.40-0.30 No microbial proliferation  Cookies, crackers, bread crusts, breakfast cereals, dry pet food, peanut butter
 0.30-0.20  No microbial proliferation  Whole milk powder, dried
vegetables, freeze dried corn

*Adapted from L.R. Beuchat, Cereal Foods World, 26:345 (1981) 


Pure water that is unencumbered has more energy and therefore can be available and used to do bad things by microorganisms.  As water comes in contact with a material substance the water's energy and water activity (aw) decrease. Water reacts differently with different material substances and can have a higher or lower water activity rating* (aw).  A water activity (aw) number closer to the top of the chart closer to 1.00 has a higher water activity while those lower have less.

Understanding and documenting how water activity is effected by different material substances provides valuable information.   Using this information provides a way for us to take proactive measures to lower water activity as we seek to improve microbial, chemical and structure stability of foods, pharmaceuticals, and other materials. 

FoodPackaging.jpg

Packaging to improve shelf life

 

 

 

 

 

Equilibrium of ingredients to make foods last longer

cookie.jpeg

Explore multi-ingredient products where water activity in each ingredient will seek to equilibrate and change the overall water activity (aw) result of the product.  This can trick people who only look at water content of each ingredient and or even the water activity individually.

      CONTACT US ABOUT------>   Water Activity (aw) 

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How to find Bromine number and index with a Karl Fischer Titrator

By Hank Levi on Sun, Apr 10, 2016 @ 08:47 AM


WHY DO WE CARE ABOUT BROMINE NUMBER AND BROMINE INDEX ANYWAY?

The degree of unsaturated hydrogen carbide (Hydrocarbon) in oil and petroleum products is indicated by Bromine number or index. Hydrocarbons containing between 6 and 10 carbon molecules are the primary components of most fuels where the process of burning them produces energy. Saturated hydrocarbons are defined by molecular structure and are defined as Alkanes.  Alkanes are the basis for petroleum fuels.  Unsaturated hydrocarbons are also defined by their molecular structure and produce less energy when burned than do saturated hydrocarbons.  Mathematically it therefore requires a greater quantity of unsaturated hydrocarbons to be burned to equal the same amount of energy produced by burning the same amount of saturated hydrocarbons.  An un-friendly environmental side effect of burning hydrocarbons is the creation of carbon dioxide.  So from an environmental standpoint you could say we prefer the lesser of two evils and prefer to burn saturated hydrocarbons vs. unsaturated hydrocarbons. For these reasons alone it would make sense that we would want to measure and quantify these hydrocarbons. 

 

HYDROCARBONS AND SOME OF THEIR USES

NAME USES
Methane Fuel in electrical generation
Ethane Chemical applications
Propane Heating and cooking
Butane lighters and aerosol
Pentane Lab & production of polystyrene
Hexane Glue
Heptane & Octane Major contributor to gasoline
Nonane

Diesel fuel

Decane

Jet fuel, gasoline and diesel

 

Although the test method ASTM2710 describes the use of an automatic potentiometric titrator the coulometric Karl Fischer method is easier to perform (see ASTMD1492-08e1).  



<BROMINE NUMBER AND INDEX BY COULOMETRIC KARL FISCHER TITRATION>

Bromine number :The amount of bromine (unit: g/100) consumed in 100g sample.

Bromine index :The amount of bromine (unit: mg/100) consumed in 100g sample.

 

<PRINCIPAL OF MEASUREMENT>

The unsaturated hydrogen carbon reacts with bromine as follows: R-CH=CH-R+Br2R-CHBr-CHBr-R- (Eq. #1)

In coulometric titration, bromine is generated by electrolysis of anolyte containing bromine ion:  2Br-Br2+2e- (Eq. #2)

 

When generated bromine is consumed according to Eq. (#1), the electrode detects bromine consumption, and continues generating bromine according to Eq. (#2).

Such bromine is generated in proportion to the electricity determined by Faraday’s Law. From Eq. (#1), Bromine reacts with coupled C=C evenly (1:1). ==>Thus, one mol of bromine(159.8g) is equivalent to 2 96500 coulomb, which means 1.2 coulomb/1mgBr2.

Based on the above principle, the electricity consumed in electrolysis is converted to the exiting bromine.

 

Special notes to obtain correct measurement results:

  1. Replace anolyte and catholyte reagent often (daily).
  2. When anolyte turns to white color replace it with new anolyte.
  3. Over use of anolyte and catholyte and not replacing it can cause results to be higher than expected.
  4. Do not share Bromine titration cell with a moisture titration cell

 Download a copy of this method

Step 1: Preparation of Reagents

Prepare the reagents and samples for measurement of bromine number and bromine index.

Use the following reagent for measurement of bromine number or index:

Anolyte Reagent: Mixture of Acetic acid (high grade) 600mL; Methanol (high grade) 260mL; 1M-Potassium bromide solution 140mL. Blend it well and use 100mL each time.

Catholyte Reagent: 0.2M-Potassium chloride solution. Use 5mL each time.

Check Solution:  0.05Wt-Cyclohexene toluene mixture (Approx. 93 ~ 102mgBr2/100g). Theoretical value is calculated by the below formula:

theoreticalbrominevalue.png

 

Step 2: Prepare Reagent for testing

Refer to the below chart for sample size:

Bromine index (mg/100g)  Sample Size (g) 

 Below 10

10 ~ 50

50 ~100

100 ~ 200

More than 200

 10 ~ 15

5 ~ 10

3 ~ 5

1 ~ 3

~ 1

For bromine number, a sample is diluted with toluene to Bromine number 0.2 (g/100g), and approximately 1g is used for measurement. Calculate the toluene to be used for diluting to Bromine number 0.2 (g/100g) with the following equation:

anotherbromineformula.png

Obtain the dilution coefficient in advance according to the following equation:

Brominedilutioncoefficient.png

 

Step 3: Measurement Procedure

Measure Bromine Number and Bromine Index

  1. Discharge 20 100μL check solution into the electrolysis cell, and press [Pre-titr.*] key.

  2. After pre-titration is finished, press [Sample*] key to enter sample name, its ID and size, and enter the dilution coefficient (D) .
    Press [MENU/HOME*] to Main display.

  3. Press [Start] key, and discharge the sample into the cell. Again press [Start*] key for titration to start.

  4. After titration is over, the measurement results appear on display with printout when a printer is connected.

*Note that different Karl Fischer Titrator Models will have different button commands.  The MKC-710 series coulometric Karl Fischer titrators come standard with pre-programmed setup for running Bromine and follow the above button commands.

We hope this information helps you get started.  If you have any questions or would like some help please contact us by clicking on the button below.

Download a copy of this method 

 

 

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How to Clean Karl Fischer Titrator Electrodes

By Hank Levi on Wed, Mar 30, 2016 @ 03:31 PM

How to Clean Karl Fischer Electrodes:

A Karl Fischer Titrator uses two electrodes.  The Inner burette (aka Generator Electrode) and the Detector Electrode.  We hope this infromation is helpful in giving some guidance on cleaing and caring for these Karl Fischer Titrator electrodes.

 

Twin platinum reference "Karl Fischer Detector Electrode" K103-M713/ K103-M714 or any other model

If the electrode is heavily stained and the potential is unstable and measurement reading fluctuates clean with nitric acid. After cleaning use methanol and wipe off with clean gauze.

Cleanelectrode.png

Single or Dual Inner burette K443-0006/ K103-0002 or any other model (aka Generator Electrode)

Periodic cleaning of the inner burette is recommended if the inner burette is stained and the electrolysis reaction will not run smoothly.  A faulty Inner Burette may cause a longer length of time in the measuring process with measurement results being recorded at higher than theoretical values.

 

Cleaning with alcohol: general method

  1. Turn off all power
  2. Disconnect the electrodes from their ports.
  3. Take out both anolyte and catholyte.
  4. Wipe off grease around sliding area with methanol.
  5. Rinse the inner burette with methanol, and fill it with approximately 10mL of methanol and then put it in a beaker. Fill the beaker with methanol up to the level of methanol inside the inner burette, and leave it for about 30 minutes.
  6. After the above 5), dry the inner burette.

 

Cleaning with nitric acid (boiling): If the color of inner burette or diaphragm does not disappear

When there is a deposition of iodine on the diaphragm or the electrode surface, clean with 1mol nitric acid (boiling):

  1. Immerse the diaphragm or the electrode surface in nitric acid, and boil with a hot stirrer.
  2. Drain out the chromate inside the cell, and rinse it with pure water for 2 to 3 times until yellowish color disappears.
  3. Clean the inner burette with methanol or with alcohol.
  4. Repeat the above steps several times when dirt does not come off.

nictricacidwarning.png

 

Cleaning with chromic acid mixture : When dirt does not come off

If foreign objects are observed on diaphragm and platinum surface, use chromic acid mixture instead of methanol for cleaning.

Chromic acid mixture:  1.5g approx. potassium dichromate dissolved in 100mL of concentrated sulfuric acid

Chromicacidwarning.png

 

 

 

 

  1. Follow the same steps as above for methanol.
  2. Drain out the chromate inside the cell, and rinse it with pure water for 5 to 6 times until yellowish color disappears.
  3. Clean the inner burette with methanol or with alcohol.

Chromewarning.png

 

How to dry the inner burette and diaphragm

Dry it in a decompression dryer for more than 2 hours.  Below sketch shows an example of commercially sold drying under reduced pressure.

 howtodryinnerburette.png

 

NOTE:  Dry the inner burette itself only after removed from the titration cell in order to avoid possible breakage of inside ceramic diaphragm.

SUGGESTION: Use a hair dryer if a compression dryer is not available. With a hair dryer, dry the inner burette well enough as long as for more than 10 minutes, especially dry the diaphragm until it is really dried. Any residue of moisture will cause high drift level.

CAUTION: Set the temperature of the constant temperature drying oven at 65°C or below.  When drying with a hair dryer, make sure not to overheat its cable and connector. Overheating may result in malfunction.

 

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Electrode Shower Cleaning for Auto Titrator Sample Changers

By Hank Levi on Thu, Feb 25, 2016 @ 12:04 PM


ELECTRODE RINSE WITH SHOWER ACCESSORY:

Sample changers that are connected with automatic titrators generally are there for a reason.  Efficiency. From an operators point of view getting multiple tests done quickly while being able to take on other tasks in the lab is a key productivity booster.  Sample changers offer various sizes ranging from as few as 6 positions for samples up to some of the largest exceeding 50 sample positions.  Sample changers either have rotating carousels or an arm that moves electrodes and nozzles from sample to sample.  Each time a sample test is completed the electrode must be cleaned before moving on to the next test.  Many sample changers offer as standard a dip rinse between sample testing and as the name suggests it's really nothing more then dipping the electrode in clean water or solution.  For some samples this process is sufficent but for others it is not enough to effectively clean the electrode before the next test.  Luckily most manufacturers of sample changers offer additional cleaning power with the use of a shower rinse system.   Below is a video showing how a shower rinse process works.   Water is stored in a container and then is flushd and rinsed in one of the sample positions designated as the cleaning station.  Water is evacuated via tubes to a drain or sink.  


 
 
 
 
 
 
 
 

 

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Automatic Tensiometer vs. Manual Tensiometer

By Hank Levi on Mon, Jan 11, 2016 @ 11:56 AM

Ever wonder what a tensiometer looked like?   

There are MANUAL TENSIOMETERS that look like this:

 manual_tensiometer-resized-600.jpg
 

PROS:

  • >Great for hands-on learning
  • >Can use virtually anywhere (does not require electricity)
  • >Easy to learn how to use
  • >Less expensive

CONS:

  • >It's manual.  You have to twist the dials by hand
  • >There is a technique to getting repeatable results
  • >Human error potential is higher
  • >Need to record results by hand

 

VIDEO DEMONSTRATION FOR MANUAL TENSIOMETER

 
 
 
 
 
 
 
 
 
 

There are AUTOMATIC TENSIOMETERS that look like this.

DY-300small.jpg
 

PROS:

  • >Easy to operate.  Press a button and walk away
  • >Run more tests quickly with high repeatability
  • >Ability to record and report data results (store historical data too)
  • >Dynamic testing features including time tests and Lamella length and more
  • >Most handle both DuNouy Ring and Wilhelmy Plate

CONS:

  • >More Expensive
  • >Some models require a computer (some don't)

VIDEO DEMONSTRATION FOR AUTOMATIC TENSIOMETER

 

To help prospective users evaluate and compare the different types of models available in the market we have prepared a reference document we call the: 

                    "Tensiometer Selection Matrix"

This matrix is not necessarily brand specific as it was designed to help those seeking to compare capabilities and prices among popular manual Tensiometer models vs. popular Automatic or "digital" Tensiometer models. 

We hope you find the Tensiometer Selection Matrix helpful in your search and evaluation of Tensiometers.

 

                        Created on 09/22/11 at 12:43:16

Click here to go to the platinum page


 

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