Introduction and Agenda

Transcription

1 Quality Control Testing Training 2014 Introduction and Agenda My name is Frank Lecrone. AquaPhoenix Scientific, Hanover PA 20 years experience in the industrial water test kit industry Agenda (modified as necessary for discussions) General Information Test Methods Boiler Water Tests Cooling Tower Tests Please Don t Let Me Lose You Ask questions at any time during the presentation. You can appear to be a fool for 5 minutes by asking a question, or you can be a fool for a lifetime by not asking. Testing validates your water treatment program to your customers. Stay awake because I m going to ask you questions too and may throw things at you. 1

2 You have many options to choose from. What s Important In Testing? Safety Glasses, Gloves, Proper Clothing RTFM (read the free manual) Clean Glassware ( plastic ware ) Avoid cross contaminations Replace sample vials Rinse vial with new samples Ensure fresh/proper reagents Expiration Date Particulate in the bottle What s Important In Testing? Take a representative sample Where to pull sample? Sample Preparation Sample cooler Oxygen sampling Test samples immediately Proper lighting to see results Safety 2

3 Ensure Proper Lighting What s the Work Environment? Dark Boiler Room Use a white background Paper towel Piece of paper New light bulbs Full spectrum light is best Sun light Colorimeters contain their own light source How Do You Express Your Results? I m down to 180! Great? Pounds or Kilograms (396 lbs) Nitrite vs. Sodium Nitrite Sulfite vs. Sodium Sulfite Mo (x1.7) vs. Molybdate (x2.5) vs. Sodium Molybdate Percentage vs. ppm 1% is 10,000ppm Microseimens vs. milliseimens Be Sure to Compare Apples to Apples! Ensure Accurate Sample Size 4 ml Sample!! 3

4 Ensure An Accurate Result Use a flat surface to verify sample volume in vial How to read a meniscus (A or B?) Use volumetric glassware Pipet Graduate Cylinder Sample Vial Beaker? Nitrite = 5ml sample size Inadvertently take a 6ml sample? Start with a 20% error Consider any dilution factors A B Prepare for Interferences Identify them when possible Use a different chemistry Read procedures Dilution Remember to account for the dilution factor Accurately dilute Filter Both positive and negative Inhibitors built into the test Hardness and metals Be consistent *From Hach PN-10 UV OP procedure Test Methods Variety of Test Methods What s Appropriate for your Needs? Considerations What parameter are you testing for? ph Hardness Phosphate Bacteria Accuracy Cost Per Test $$ Quick Results Ease of Use 4

5 How Close is Close Enough? Accuracy Accuracy vs. Precision How accurate do you need? Drop Count vs. Buret Titration Visual Color vs. Colorimeter Drop Count Kits Results are +/- 10% Quick, Inexpensive and Easy In Water Treatment Trends are Important Accurate not Precise Precise not Accurate Color Blindness Ishihara Test 5-8% of men 0.5% of women How s Your Vision? Test Methods Titrametric Buret Drop Count Colorimetric Color change Visual (test strips, color block) Meter Electronic ph Conductivity ISE 5

6 Boiler Water Feed Water Tests (condensate and make up) Oxygen Hardness Iron Boiler Tests Alkalinity P/T, OH Chelant Free, Total Chlorides Conductivity Hardness Total, Ca, Trace Iron Molybdate OP (Phosphonate) Oxygen Scavenger ph Phosphate Polymer Sulfite Popular Boiler Water Titrations Alkalinity Titrant usually sulfuric acid (can be HCl) (P) phenolphthalein and (T) total (M) Chloride Titrants Silver Nitrate (Argenometric) or Mercuric Nitrate Hardness Titrant EDTA Total & Ca Phosphonate (OP) Titrants Thorium Nitrate or Bismuth Nitrate Sulfite Titrant Potassium Iodide-Iodate Titrations Accurate Sample Add Buffer (if necessary) Add Indicator Accurately Measure Titrant End Point Calculate Results Buret Titrations Good accuracy Can be cumbersome in the field Glass burets are expensive and breakable Digital Titrator Good accuracy Good for field use Drop Count Test Kits Inexpensive Portable Not as accurate 6

7 Titration Calculations What s important? Proper technique How to read buret Hold dropper bottle vertically Titrate to End Point (permanent color change) Slowly, don t over run No further color change Titrant strength Sample size How results are expressed? Titration Calculations If Titrant 1mL=20ppm as SO 3 Potassium Iodide-Iodate N/40 (0.025N) 1mL=20ppm as SO 3 (x 1.57) N/63 (0.0159N) 1mL=20ppm as Na 2 SO 3 ( 1.57) Sample Accurate 50mL Smaller the sample size, the more powerful the titrant 25mL sample? 100mL sample Results expressed? As sulfite x 1.57 = ppm Sodium Sulfite Na 2 SO 3 30ppm SO 3 = 47.1ppm Na 2 SO 3 Nitrite to Sodium Nitrite x 1.5 Increase the 5mL volume to see end point better Assume 1 drop = 50ppm as Sodium Nitrite Accurately add 5mL of DIW = How much change? 7

8 Properly sampled Test Immediately Sample must be cooled How expressed? -Sodium Sulfite (x 0.64) -Sulfite (x 1.57) Properly Acidified < ph 4 Interferences -Ferrous Iron + -Sulfide + -Copper - -Nitrite - -Any Oxidizable substance Sulfite Oxygen Tests and Scavengers Oxygen -CHEMetrics ppb test -Sampling Technique Important Sulfite -Sample Properly -Cool the Sample (sample cooler) -Test Immediately Hydrazine DEHA MECOR Hydroquinone Erythorbates (Na salts) Colorimetric Testing Colorimeter or Spectrophotometer Uses internal light source Multiparameter meters Single Parameter meters Visual Uses external light source Color card Block Wheel Test strip Measures color change or intensity Equate color change to analyte concentration 8

9 3 Things Needed for a Good Test Result Colorimetric Tests for Water Treatment Colorimetric Testing Tips Technician* Instrument or Equipment Reagents *80-85% of the time an error occurs, it is user error or a sample problem Aluminum Ammonia Bromine Blue Color Chlorine Chlorine Dioxide Copper DEHA Dissolved Oxygen Hydrazine Hydroquinone Iron Manganese Molybdate Nickel Nitrate Ozone ph Phosphate Phosphonate Polymer Silica Sulfate Tannin Tolytriazole Zinc Others? Clean sample vials No fingerprints or dirt Orientation of vial in meter Matched sample cuvettes Run a blank or known standard Know your procedure Time for reaction Digestion (UV, acid) 9

10 ph Electrochemical Tests Conductivity ORP (mv) ISE Ion Selective Electrodes High end ph meters (mv) Boiler Tests Review RTFM Read the Free Manual (procedure) Pay attention to Sample size Where to pull sample? Drop equivalency / titrant strength How results are expressed Keep Equipment and Apparatus Clean Dropper tips Electrodes Sample vials Be Consistent Safety Alkalinity Aluminum (if in system) Biocides Bacteria Chlorides Conductivity (TDS) Copper (if in system) Hardness Total, Ca Iron Molybdate OP, Phosphonates ph Phosphate Polymer Cooling Tower Tests 10

11 Conductivity Tests Calibrate Weekly Use standard close to testing value Keep Clean Rinse after testing Can store dry Conductivity Neutralizer Phenolphthalein Indicator Acid which doesn t effect conductivity How expressed? MicroSiemen µs Micromhos Millisiemen ms (1000µS) TDS (ppm) Conductivity Examples (Data Differs Slightly Depending on the Source) Theoretical Pure Water microsiemens/cm Demineralized Water to 1.0 microsiemens/cm Reverse Osmosis Water0.8 to 3.0 microsiemens/cm Distilled Water.5 to 10 microsiemens/cm Rivers in USA microsiemens/cm Tap Water 100 to 2000 microsiemens/cm 0.01M KCl Solution 1413 microsiemens/cm Sea Water 40,000 to 100,000 microsiemens/cm 5% NaCl Solution 70,000 microsiemens/cm 10% H 2 SO 4 Solution 140,000 microsiemens/cm Test Strips Colorimetric Color block Meters Single Junction Electrode Double Junction Electrode Dirty Samples Slower reaction time Combination meters ph Conductivity (TDS) ORP Temp ISFET Store dry More durable What Method Works Well with Condensate? Low Ionic Strength LIS Adjuster (KCl) LIS Buffer High quality probe $ Colorimetric ph Testing 11

12 ph Meter Maintenance ph Electrodes Keep Hydrated Rinse after testing Electrode storage solution Buffer? Water? Soak / rehydrate if dried out Calibrate Daily Bracket your test levels Fresh buffers Cap Bottle ASAP Popular Cooling Tower Titrations Alkalinity Titrant usually sulfuric acid P (phenolphthalein) and (T)otal (M) Chloride Titrants Silver Nitrate (Argenometric) or Mercuric Nitrate Hardness Titrant EDTA Total & Ca Nitrite (Closed Loop) Titrants CAN or Potassium Permanganate Phosphonate (OP) Titrants Thorium Nitrate or Bismuth Nitrate Keys to Accurate Titrations Ensure Proper Testing Technique Ensure Proper Titrant Strength Buret titrant Drop count titrant Ensure Proper, Accurate Sample Size Hold bottle vertically Drop sizes are different Dropper tips Static charges Clogged / malformed tips (CAN) End point in at least 10 drops How are the results expressed? 12

13 Alkalinity P Alk ph=8.3, T Alk ph = 4.6 Titrate Slowly -Permanent color change -CO2 must be gassed off Hydrate Alkalinity Carbonates Phosphates Use Barium Chloride to precipitate above Use HCl as titrant to prevent sulfates ppt. High Halogens can Bleach Indicators 2P-T=Hydrate Alk When P>½T 13

14 Chloride Low Concentrations -Mercuric Nitrate Titrant -Better Low End Sensitivity -Indicator Short Shelf Life Calling End Point -Be Consistent -Run Standard to Confirm Endpoint Interferences -Positive Interferences Bromide, Orthophosphate, Sulfide -Dilute out interferences Metals Will Interfere Hardness -Add 1 drop titrant before indicator, count the drop -EDTA titrant will tie up the interfering metals before they can tie up the indicator Properly Buffered? -Total, ph 10 -Ca, ph 12 Sensitivity of the Test? 14

15 Nitrite Detection level down to 0.5ppm Detection level down to 5ppm Detection level down to 1ppm How expressed? -Sodium Nitrite (x 0.67) = Nitrite -Nitrite (x 1.5) = Sodium Nitrite CAN test -Sample Properly Acidified ph<2 Permanganate test -Glycols Interfere -Titrant Shelf life -Heat and Light Sensitive 15

16 Run Blank of Make Up Water Interferences (next slide) High Alkalinity Halogens (Cl Br F) Polyphosphate Phosphate Molybdate >20ppm Properly ph Buffered How expressed? -Active OP -HEDP -PBTC -AMP -As product OP OP UV Digestion Interferences 16

17 Phosphonate (OP) Titration (drop test) Titrants Thorium Nitrate or Bismuth Nitrate Many interferences Fluoride Phosphate Chlorine Properly Buffered? Fluoride suppressor if necessary Colorimetric (UV, acid, microwave digestion) Before and after Phosphate Test 10 minutes (start this test first) Heavy UV lamp transformer Splitter for 2 lamps Polymer Test Turbidimetric Test Two Reagent System Make Standards Visual (color card) Meter Options Use Actual Polymer Blend Create Custom Curve Bacteriological Tests Sampling Important Dip Slides Short Shelf Life Incubate F hours Slow results Disposal with Bleach 3M Petrifilm ATP Quick results What does # mean? Look at trend UV lamp 17

18 RTFM Cooling Tower Tests Review Read the Free Manual (procedure) Pay attention to Sample size Drop equivalency / titrant strength How results are expressed Keep Equipment and Apparatus Clean Dropper tips Electrodes Sample vials Be Consistent Safety Questions or Comments? Thank You for Your Attention Frank Lecrone AquaPhoenix Scientific Inc. 18