LaMotte DPC-52 User Manual

DPC-52

Water Testing Laboratory Manual

CODE 3509-01

DPC-2 Colorimeter Version

TABLE OF CONTENTS

Page

Introduction.................................................. 4

Tester’sGuide................................................. 4

Free,Combined&TotalChlorine.................................5

Bromine.....................................................7

pH......................................................... 8

CyanuricAcid................................................ 9

Copper ..................................................... 10

Iron ....................................................... 11

Alkalinity................................................... 12

CalculatingtheVolumeofPools&Spas ...........................13

AcidDemand&pHAdjustment.................................13

BaseDemand&pHAdjustment.................................15

CalciumHardness ............................................16

PartsList&Service........................................... 17

INTRODUCTION

The Water Lab is a colorimeter laboratory for rapid, accurate measurement of pool or spa water chemistry. The Water Lab may be used to identify the causes of water quality problems and to determine appropriate corrective treatment. The test results obtained with this laboratory may be employed in most computer programs for pool water treatment. The outfit is portable, compact, and easy to use. An inexperienced operator with no knowledge of chemistry can learn to use the Water Lab in a matter of minutes. Careful attention to the procedures given in this manual is all that is required to produce consistently accurate and reliable test results.

The central component of the Water Lab is the battery-powered colorimeter, which electronically measures the color produced in the chemical test reactions. A separate User’s Guide provides general operating procedures for the instrument and describes the proper technique for operating the Direct Reading Titrators used in the alkalinity and calcium hardness tests. Once you have become familiar with the general operating techniques of the Water Lab and its components, you will only need to refer to the condensed instructions provided on the separate laminated card.

TESTER’S GUIDE

*WARNING: Reagents marked with a * are considered to be potential health hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents see MSDS CD or www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail, phone or fax.

When conducting a series of tests on a given pool sample, you only need to set the

•

colorimeter to 0.0 (zero) with the pool sample blank one time.

• Keep ALL reagents tightly capped between tests.

•

Do not touch reagent tablets with your fingers. Use the tube cap or tweezers.

•

Fill the test tubes to the line, with the bottom of the liquid (meniscus) on the line.

•

Carefully wipe off colorimeter tubes before reading. Use a clean, soft tissue.

•

Do not mix up pipets (eye droppers).

•

When adding drops of reagents, hold dropper bottles and pipets vertically to insure consistent drop size.

•

Thoroughly wash and rinse out test tubes when finished with testing. Use deionized water to rinse tubes.

FREE AVAILABLE, TOT AL & COMBINED CHLORINE DPD METHOD

Chlorine is added to pool water as a sanitizing agent to kill bacteria and other disease producing organisms. Chlorine is also used to control algae and to remove undesirable odors and colors.

Depending on what commercial chlorine product is used, chlorine may be added to pool water in a variety of forms - chlorine gas, liquid sodium hypochlorite, granular calcium hypochlorite, or organic chlorine compounds. When chlorine is added to water, it quickly forms hypochlorous acid, HOCl, the active ingredient which is responsible for chlorine’s sanitizing capabilities. The hypochlorous acid is also known as the Free Available Chlorine. The presence of other compounds in the pool may consume the hypochlorous acid, or free available chlorine, and form other chloro compounds, such as chloramines or other organic nitrogen compounds. As chlorine combines with other compounds in the pool water, much of its sanitizing capability is lost, and higher levels of chlorine are necessary to achieve the same germ free water. Therefore, it is essential to chlorinate to the point of establishing a free available chlorine residual and then maintain it at the recommended level. For most pools, the free available chlorine residual should be maintained between 1.0 - 3.0 ppm.

The LaMotte DPD liquid test method distinguishes levels of Free Available Chlorine, Combined Chlorine and Total Residual Chlorine, using a single test sample.

RANGE: 0.1 - 5.0 ppm METHOD: In the absence of iodide, free available chlorine reacts instantly

INTERFERENCE: The only interfering substance likely to be encountered in pool

Continued on next page...

with the buffered diethyl-p-phenylenediamine indicator (DPD) to produce a red color in proportion to the amount of chlorine present. Subsequent addition of potassium iodide produces a rapid color response from the combined forms of chlorine (chloramines).

water is oxidized manganese. The extent of this interference can be determined by treating a sample with sodium arsenite to destroy the chlorine present, so that the amount of interference can be measured.

PROCEDURES

A. FREE AVAILABLE CHLORINE

1. Fill the water sample bottle (0688) with the pool water sample.

2. Dispense the water sample into a clean colorimeter tube (0967), until the tube is

filled to the 10 mL line.

3. Insert the tube containing the untreated sample into the colorimeter chamber, and press the “Chlorine” button once. When the display indicates “Blank 0.0,” press the “Chlorine” button again. Remove tube.

4. Add 5 drops of DPD 1A Free Chlorine Reagent (P-6740) and 5 drops of *DPD 1B Free Chlorine Reagent (P-6741).

5. Cap and mix. The development of a pink color indicates the presence of Free Available Chlorine.

6. Insert the treated sample into the colorimeter chamber. Read result in ppm Free Available Chlorine. Do not discard this treated sample if the test for Total Chlorine is to be made.

B. TOTALRESIDUALCHLORINE

1. Add 5 drops of *DPD #3 Total Chlorine Reagent (P-6743) to the sample from Step A.6. Cap and mix. An increase in color indicates the presence of Combined Chlorine.

2. Insert the treated sample into the colorimeter chamber and press the “Chlorine” button. As soon as the display stabilizes, read result in ppm Total Residual Chlorine.

C. COMBINED CHL ORINE

The Combined Chlorine concentration equals the difference between the Total Residual Chlorine reading (B.2.) and the Free Available Chlorine reading in (A.6.) above.

TotalResidualChlorine- Free Available Chlorine = Combined Chlorine

A Combined Chlorine level of 0.2 ppm or greater should be treated.

NOTES:

If either Chlorine reading exceeds 5.0 ppm, the display will flash, repeat the test procedure on a diluted sample and multiply the test result by the appropriate dilution factor.

Levels of Chlorine above 10 ppm can cause a bleaching effect of the DPD indicator and may give a false indication that no chlorine is present. If it is possible that the chlorine concentration may be greater than 10 ppm (e.g., after shock treatment), perform the test on a diluted sample and multiply the test result by the appropriate dilution factor.

If, after adding both DPD 1A Free Chlorine Reagent and *DPD 1B Free Chlorine Reagent, a cloudy precipitate is present, retest by adding reagents first and water sample second to the tube.

+ 14 hidden pages