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Dropper bottle Procedures Index
1) Iron Analysis 2) Zinc Analysis
3) Acid Analysis 4) Caustic analysis
5) Sulfate analysis
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Robinson Consulting
Terry Robinson
329 W. 31st St
South Sioux City, NE. 68776
Tel/Fax: 402.494.8250
Email: Terryrobinson@galvanizingtestkits.com
Analysis of Iron in Preflux and Pickling Acid tanks using the dropper bottle method
1.0 Purpose
1.1 To provide quick, reliable in house test results.
2.0 Reagents
2.1 IRON TITRANT: Potassium Dichromate (K2Cr2O7 M.W. 294.19). This solution is used dropwise to determine the amount of iron in the sample. This yellow solution is toxic. Make sure to flush with water when it comes in contact with skin. Read MSDS sheet
2.2 IRON BUFFER: This solution is a mixture of Sulfuric acid and Phosphoric acid and is very corrosive. Make sure to flush with water when it comes in contact with skin. Read MSDS sheet
2.3 IRON INDICATOR: Clear solution needed to determine color change when using titrant.
3.0 PROCEDURE
3.1 Use 0.5 ml (cc) sample for acid or use 5 ml (cc) sample for preflux or 1 ml (cc) sample for rinse tanks. Using the syringes provided add the appropriate size sample to 25 ml distilled water in the 50 ml flask.
3.2 Add 2 ml Iron buffer to the solution.
3.3 Add 4 drops of Iron indicator to solution and swirl to mix.
3.4 Titrate with Iron Titrant Potassium Dichromate (K2Cr2O7) to blue end point making sure to count the drops of titrant needed to change the color to blue. Swirl solution after each drop.
4.0 CALCULATIONS (Specific gravity of acid assumed 1.30 g/ml)
4.1 For a 0.5 ml sample each drop is equal to 0.5 % wt. iron or 5000 ppm.
4.2 For a 1.0 ml sample each drop is equal to 0.25 % wt. iron or 2500 ppm.
4.3 For a 5.0 ml sample each drop is equal to 0.05 % wt. iron or 500 ppm.
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Analysis of Zinc in Pickling Acid using the Dropper Bottle Method
1.0 Purpose
1.1 To provide quick, reliable in house test results.
2.0 Reagents
2.1 ZINC TITRANT: E.D.T.A. ( C10H14O8N2Na2 * 2H2O ) F.W. 372.24
2.2 ZINC BUFFER : Ammonium Hydroxide ( NH4OH) 26 degree baume. Ammonium Chloride ( NH4Cl) M.W. 53.49. Read MSDS before using.
2.3 ZINC INDICATOR : Erichrome Black T, absolute ethanol and triethanolamine.
3.0 Procedure
3.1 Use 0.1 ml sample of acid and transfer into 60 ml shaker bottle.
3.2 Add 40 ml of distilled water to bottle
3.3 Add 5 ml of zinc buffer to bottle. Shake well until green liquid turns to orange/brown.
3.4 Using medium filter paper, filter the orange/brown solution. Then use the clear solution for the zinc titration. Small amounts of distilled water can be used to was down the filter paper.
3.5 Add 1-2 drops of zinc indicator to the titrating beaker. Solution should be wine-red in color.
3.6 Titrate sample using titrant (E.D.T.A.) in the calibrated dropper bottle from wine -red to blue endpoint. Keep track of the number of drops to determine amount of zinc.
4.0 Calulations ( Specific gravity of acid assumed 1.3 g/ml)
4.1 For a 0.1 ml sample multiply the drops used to change the color from wine-red to blue by 0.5 % wt.
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Analysis of Acid in Pickling Acid tanks using the dropper bottle method
1.0 Purpose
1.1 To provide quick, reliable in house test results.
2.0 Reagents
2.1 ACID TITRANT : Sodium Carbonate (Na2CO3) M.W. 105.99. This solution is used dropwise to determine the amount of acid in the sample. Do not shake vigorously. Store at temperatures above 70 degrees F. Make sure to flush with water when it comes in contact with skin. Read MSDS sheet before using.
2.2 ACID INDICATOR: Bromophenol Blue ( C19H9Br4Na2O5S) M.W. 692.0 g.
3.0 Procedure
3.1 Use 1.0 ml (cc) acid sample or 2.0 ml (cc) rinse water sample. Using the syringe provided add the appropriate size sample to about 20 ml distilled water in the 50 ml flask. Swirl the solution to mix.
3.2 Add 1 -2 drops of Acid indicator.
3.3 Add Acid titrant dropwise, mixing after each drop until solution turns blue..
4.0 Calculations ( Specific Gravity assumed 1.0 g/ml )
4.1 For a 1.0 ml sample each drop is equal to 1.0 % Sulfuric acid or 10,000 ppm.
4.2 For a 2.0 ml sample each drop is equal to 0.5 % Sulfuric acid or 5,000 ppm.
4.3 If testing for HCl ( Hydrochloric Acid) multiply results by 0.74.
4.4 If specific gravity or baume of solution is known determine true %weight acid by the following formula.
Specific gravity g/ml = 145/ ( 145- baume)
True % wt. acid = ( % acid in dropper bottle test X ( 1/specific gravity in grams/ml))
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Caustic Concentration Dropper Bottle Test as a Function of
Sodium Hydroxide and Sodium Carbonate concentration.
1.0 Purpose
1.1 To provide reliable data to galvanizing pickle man and to determine when to add more caustic to the tank.
2.0 Reagents
2.1 CAUSTIC TITRANT: Dilute hydrochloric acid solution ( HCL). Caution solution is corrosive. Read MSDS before using.
2.2 CAUSTIC INDICATOR: Phenolphthalein indicator. ( pH Sensitive)
3.0 Procedure
3.0 Obtain a representative sample from the middle of each caustic tank.
3.1 After solution cools to room temperature, place a 1 ml (cc) sample into a 50 ml flask.
3.2 Add 20 ml (cc) of distilled water to the flask and swirl to mix.
3.3 Add three drops of caustic indicator (Phenolphthalein) . Solution should be red.
3.4 Add titrant ( hydrochloric acid solution) dropwise, mixing after each drop, until red solution turns to clear (white).
4.0 Calculating Results:
4.1 Each drop it takes to turn the solution clear ( white) = 0.5 % Caustic.
4.2 Typically 3 to 4 oz per gallon of dry caustic is = to 3.00 to 4.00 %wt Caustic tested.
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Sulfate Concentration in Galvanizing Preflux .
1.0 Purpose
1.1 To monitor residual sulfate that is carried over into the preflux tank from the acid and rinse tanks.
1.2 To evaluate the rinsing efficiency by the history of sulfate buildup in the preflux tank.
2.0 Additional equipment needed
2.1 Purchase a centrifuge with 10-15 ml centrifuge tubes (2 qty) to perform this test.
3.0 Reagents
3.1 Barium Chloride ( BaCl2) solution is used to precipitate ( milky white solid) Barium Sulfate. Barium Chloride is toxic wear rubber gloves and safety glasses when handling. Wash hands when done. Read MSDS before using.
4.0 Procedure
4.1 Obtain a preflux sample and let it cool down while the particulate matter settles to the bottom..
4.2 Using the 10 ml (cc) syringe place exactly 3 mls of clear preflux liquid into each of the 2 test tubes
4.3 Using the dropper bottle of Sulfate Precipitation solution, add exactly 1 drop of Barium Chloride to the first test tube and look for a precipitate to form. (cloudy, white ). Make a note if the cloudy white precipitate was formed.
4.4 Stopper the first test tube that the BaCl2 was added to and invert the test tube several times.
4.5 Stopper the second test tube and place both test tubes opposite each other in the centrifuge and centrifuge the precipitate to the bottom. ( about 2-3 minutes.) The solution should be clear to continue.
4.6 Now place 1 drop of Barium Chloride solution in each of the test tubes and look for a precipitate. ( First test tube should have 2 drops of Bacl2 and second should have one drop of Bacl2)
4.1 Continue this procedure until no additional precipitate is observed when the Barium Chloride is added. ( Test tube one will show no sign of precipitate first then test tube 2 will follow after another drop of BaCl2 is added)
4.2 Record the drops of BaCl2 used to precipitate the cloudy BaSO4 for one test tube only.
Note : The white precipitate can easily be cleaned off the walls of the test tube with
acidic acid or vinegar.
5.0 Calculations
5.1 Every drop of Barium Chloride solution added to the test tube that shows a precipitate ( Milky white) is = to 0.1 % wt Sulfate in the preflux tank.
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