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CONDUCTIVITY Direct Measurement Method APPENDIX La For Water and Sea water Page 1 of 2 Introduction Conductivity,as it applies to water analysis,is a measurement of water's capacity for conveying electrical cur- rent and is directly related to the concentrations of ionized substances in the water.Once correlations have been made beiween conductance values and the characteristic norms of the system bring monitored, it becomes a useful measurement in managing water processing.Depending on the particular application,a change in con- ductivity can signal such th.•as as the need for adding chemicals or regenerating the system. Conductivity measurements are commonly used to determine the purity of demincralized water and total dis- solved solids in boiler and cooling tower water. The method of measurement used in the following procedure is by direct measurement with a Hach Conductiv- ity Meser having a range of 0 W 20,001 micromhos/cm.With sample dilution,higher levels of conductance can be determined. A Sodium Chloride Standard Solution, 1000 mg/L(1990 micromhos/cm)is available from Hach to check the accuracy of the instrument. H'A1RNING Some of rhe chemicals used in this procedure maybe hazardous to the health and safery ofthe user ifinappropriately handled oraccidentally misused.Please read all warnings on the reagent F, labels and read the safety section ofthis manual.Ifyou have questions or would like a rrorint of the safetysertion,please contact Hach.In the procedure,hazardous substances appear in italic typeface wherever theyare used in the test and deserve extra carr in handling.It is always good practice to wear safetyglasses when handling:hemicals. Wash thoroughly ifcontact occurs. Follow instructions carefully. Sample Considerations When preparing to make conductivity measurements,some considerations shoulr'be given to the nature of the sample solution to ensure accurate results.Far example,if measuring very low lev,;ts of conductivity,it may be necessary toprotect the sample from atmospheric gases such as carbon dioxide or ammonia.These gases will dissolve readily in water,causing rapid changes in conductivity.To minimize these effects,the sample can be boiled and then placed in it covered container for cooling. If the sample is apt to contain significant amounts of hydroxide as can be the case with boiler water,the sample should first be neutralized to avoid erroneously high readings.Gallic Acid Solution is available from Mach for that purpose.The sample is neutralized by adding four drops ofPhenolphthalein] leatorSolottion to 50 rnL of sample and then adding Gallic Acid Solution drop-wise until the pink color completely disappears. Sampling and Storage Collect samples in clean plastic or glass bottles. Samples should be analyzed as soon as possible after collection but can be stared at least 24 bourn by cooling to 4°C(39F) or below. Warm sample to 25°C (687)before analyzing. Ptt9oedure 1. Insen the Conductivity Meter Scale into the meter and press the COND SELECT switch.Select the high- ext range.Sce A'ote A. 2 Connect the probe assembly to the PROBE INPUT on the spectrophotometer panel. --- —-- - ---- ------ 3. Immerse probe in it beaker containing the sample solution.The depth of the solution must be sufficient to allow the probe to be immerged to the.vent holes.Agitate the probe or tap it on the beaker to ftaw any : bubbles in the electrode area. 4. Select the appropriate range,beginning with the highest tinge and working down.If the reading is in the lowest 10%of the range,switch to the next lower range.'fake the reading.Ser Notes 6 and C. .