TA BLE OF CON TENTS
Introduction.................................................................................. 4
Corrosivity Index Calculations ...................................................... 5
Alkalinity...................................................................................... 7
Phenolphthalein............................................................................. 7
Total Alkalinity .............................................................................. 8
Calcium Hardness ......................................................................... 9
Testr pH10 ............................................................................... 10
Temperature................................................................................ 10
TDSTest r Low ............................................................................ 10
Phosphate in Water..................................................................... 12
Recommended Standardization Practices ...................................... 14
3
IN TRO DUC TION
A formula developed by Dr. Wilfred F. Langelier, of the University of
California at Berkeley, is used to keep potable waters in balance to prevent
corrosion on the one hand, and scale formation, on the other. This
formulation is known variously as the “Saturation Index” or the “Langelier
Equation”. It is stated as follows:
TF + TDSF - CF - AF = pHS
pH - pHS = Saturation Index
In this equation, the pH is read from a sample of water using the pocket
pH meter, and is recorded on the worksheet directly as pH units.
Temperature, Calcium Hardness, Alkalinity, and Total Dissolved Solid test
procedures are performed on the sample, the correct factor for each result is
taken from table on page 4, and the results are recorded on the worksheet.
Temperature and Total Dissolved Solids factors are added together.
Alkalinity and Calcium Hardness factors are subtracted from this sum. The
result is the solubility pH or pHS. pHS is then subtracted from measured
pH to give the corrision index, also known as the saturation index or
Langlier index.
NOTE: Phosphate testing is included in this kit, however, phosphate
results are not required to calculate a Saturation Index. The test is included
if you add a phosphating compound to inhibit corrosion. See page 11 for
procedure.
4
CORROSIVITY IN DEX CAL CU LA TIONS
The Corrosivity Index (Langelier’s Saturation) is used to determine
whether a water supply will support and deposit calcium carbonate. This
deposit acts as a buffer against leaching of various metals within the
distribution system; the primary concern of which is lead.
The Corrosivity Index is figured using five basic factors: pH, calcium
hardness, total alkalinity, temperature, and total dissolved solids. The
resulting formula is used to calculate the Corrosivity Index as follows:
TF + TDSF - CF - AF = pHS
Corrosivity Index = pH - pHS
With this information a water supply operator can quickly calculate the
Corrosivity Index for any system.
pH = pH Factor
TF = Temperature Factor
CF = Calcium Hardness Factor
AF = Alkalinity Factor
TDSF = Total Dissolved Solids
Factor
The Corrosivity Index should be maintained at a positive value between 0
and +0.5.
If the Corrosivity Index is 0, the water is perfectly balanced.
If the Corrosivity Index is negative, corrosion tendencies are predicted.
If the Corrosivity Index is positive, scale forming tendencies are predicted.
NOTE: Use supplied worksheets for Index Calculations.
Read directly with pH tester
Read temperature in °C, use Index
Calculation Chart
Titrate for calcium hardness, use
Index Calculation Chart
Titrate for total Alkalinity, use
Index Calculation Chart
Use Pocketester and Index
Calculation Chart
5
INDEX CALCULATION CHART
Total Dissolved Solids
ppm = CF ppm = AF °C = TF
Calcium Hardness &
Total Alkalinity Temperature
0 9.70 10 1.00 0.0 2.60
100 9.77 25 1.39 4.0 2.50
200 9.83 50 1.70 8.0 2.40
300 9.85 75 1.87 12.0 2.30
400 9.86 100 2.00 16.0 2.20
600 9.87 150 2.15 20.0 2.10
800 9.89 200 2.30 25.0 2.00
1000 9.90 300 2.48 30.0 1.90
400 2.60 40.0 1.70
800 2.90 50.0 1.55
1000 3.00
¾ ¾
EXAMPLE: A water sample was tested and found to have the following
characteristics:
Test
Temperature
Total Dissolved
Solids
Measured
Value Factor
10.0°C
TF (Temperature Factor) 2.35
300 ppm TDSF (Total Dissolved
Solids Factor)
Calcium Hardness 75 ppm CF (Calcium Hardness
Factor Value
from Chart
9.85
1.87
Factor)
Total Alkalinity 100 ppm AF (Alkalinity Factor) 2.00
pH 8.5 pH 8.5
CALCULATIONS:
Soluability pH (pHS) = TF + TDSF - CF - AF
pHS = 2.35 + 9.85 - 1.87 - 2.00
pHS = 8.33
Langelier Saturation Index (LSI) = Measured pH - pHS
LSI = 8.5 - 8.33
LSI = 0.17
6
AL KA LIN ITY
QUANTITY CONTENTS CODE
15 mL *Alkalinity Indicator #1, pH 8.3 *3870-E
15 mL *Alkalinity Indicator #2, pH 4.5 *3869-E
60 mL *Alkalinity Titration Reagent B *4493DR-H
1 Titration Tube, 5 mL, with cap 0778
1 Direct Reading Titrator, 0-200 Range 0382
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents
go to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail,
phone or fax.
NOTE: Carefully read the instruction manual for the LaMotte Direct
Reading Titrator before performing the titration as described below. The
titrator is calibrated in terms of Alkalinity expressed as parts per million
(ppm) calcium carbonate (CaCO3). Each minor division on the titrator
scale equals 4 ppm CaCO3.
PRO CE DURE
PHENOLPHTHALEIN (P) ALKALINITY
NOTE: P Alkalinity results are not required for Corrosion Index
Calculations.
1. Fill titration tube (0778) to 5 mL line with the water sample.
2. Add two drops of *Alkalinity Indicator # 1 (3870) to titration tube.
Cap and mix. If a pink to red color does not develop in solution, P
alkalinity is zero.
3. If a red color develops, P Alkalinity is determined. Fill the Direct
Reading Titrator with Alkalinity Titration Reagent B (4493DR) as
described in instruction manual. Insert titrator in center hole of
titration tube cap
4. Slowly depress plunger and swirl after each drop until RED color
disappears. Read test result directly from the scale where the large ring
on the Titrator meets the Titrator barrel. Express result as P Alkalinity
in ppm CaCO3.
EXAMPLE: Plunger tip is 3 minor division below line 80. The test
result is 80 plus 3 division x 4 equals 92 ppm, since each division is
equal to 4 ppm.
7
5. If plunger tip reaches the bottom line on the titrator scale (200 ppm)
before the endpoint color change occurs, refill titrator and continue
titration. When recording test results, original amount of reagent
titrated (200 ppm) must be included.
NOTE: Do not move the titrator plunger after P alkalinity endpoint
has been obtained, as the T Alkalinity titration is a continuation of
the P Alkalinity titration.
TOTAL (T) ALKALINITY
NOTE: If only Total Alkalinity is to be tested, perform Steps 1, 7 and 8
only, using a full titrator in Step 8.
6. Without moving plunger remove titrator and titration tube cap from
titration tube containing sample from Step 4.
7. Add two drops *Alkalinity Indicator #2 (3869) to titration tube.
Replace cap, swirl to mix. a BLUE color will appear.
8. Re-insert titrator in cap and continue titration until BLUE color
changes to GREEN. Read test result as T Alkalinity in ppm CaCO3.
Include in test result total amount of titration reagent added. (See
Step 5).
9. Record results in Step 8. To calculate AF Factor, refer to chart on
page 4.
8
CAL CIUM HARD NESS
QUANTITY CONTENTS CODE
15 mL *Sodium Hydroxide Reagent
w/Metal Inhibitors
50 Calcium Hardness Indicator Tablets T-5250-H
60 mL Hardness Reagent #7 4487DR-H
1 Test Tube, 5-10-12.9-15-20-25 mL,
glass, w/cap
1 Direct Reading Titrator, 0-200 Range 0382
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents
go to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail,
phone or fax.
NOTE: Carefully read the instruction manual for the LaMotte Direct
Reading Titrator before performing the titration described below. The
Titrator is calibrated in terms of Total Hardness expressed as parts per
million (ppm) Calcium Carbonate (CaCO3). Each minor division on the
titrator scale equals 4 ppm CaCO3.
PRO CE DURE
1. Fill test tube (0608) to 12.9 mL line with the water sample.
2. Add 6 drops of *Sodium Hydroxide Reagent with metal inhibitors
(4259) to test sample. Cap and mix.
3. Add one Calcium Hardness Indicator Tablet (T-5250). Cap and gently
shake to dissolve tablet. A red color will appear.
4. Fill the Direct Reading Titrator (0382) with Hardness Reagent #7
(4487DR) as described in the instruction manual. Insert Titrator in
center hole of test tube cap.
5. Slowly depress plunger and swirl sample after each drop until Red
color changes to Blue. Read test result directly from the scale where
the larger ring on the Titrator meets the Titrator barrel. Result is
expressed as Total Hardness in ppm CaCO3.
EXAMPLE: Plunger tip is 3 minor divisions below line 80. The test
result is 80 plus (3 divisions x 4) equals 92 ppm.
NOTE: If the plunger tip reaches the bottom line on the titrator scale
(200 ppm) before endpoint color change occurs, refill Titrator and
continue titration. When recording the test result, be sure to include
the value of the original amount of reagent dispensed (200 ppm).
*4259-E
0608
9
6. Re cord re sults in Step 5. To cal cu late CF Fac tor, re fer to chart on
page 4.
TESTR pH10 WA TER PROOF
(see individual instruction sheet)
TEM PER A TURE
The Model 545 Armored Thermometer is furnished with a protective
plastic shield with window openings. Range is -5°C to 45°C in 0.5°C
increments.
To use, dip thermometer into sample. Allow a minute or two for the
thermometer to stabilize, and read the Temperature on the graduated scale.
Record your results in degrees °C to the nearest 0.5 increment.
To calculate TF Factor, refer to Index Calculation Chart on page 4.
NOTE: The protective plastic shield can be removed for added visibility
in temperature measurements.
WA TER PROOF TDSTestr Low
(see individual instruction sheet)
10
PHOS PHATE IN WA TER
IN TRO DUC TION
If part of your overall corrosion control program includes the addition of a
phosphate compound to inhibit corrosion in your potable water supply, a
phosphate test should be performed to measure Orthophosphate. Follow
instructions below.
QUANTITY CONTENTS CODE
60 mL *Phosphate Acid Reagent *V-6282-H
5 g *Phosphate Reducing Reagent *V-6283-C
2 Test Tube, 10 mL 0843
1 Spoon, measuring, 0.1 g 0699
2 Pipets, 1.0 mL, plastic 0354
1 Demineralizer Bottle 1151
1 Phosphate Comparator, 0.5 - 10 ppm 3115
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents
go to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail,
phone or fax.
NOTES:
• This test determines levels of Orthophosphates only.
• This test should be run on clear samples only.
• Best results are obtained when solution temperatures are 23- 25°C.
PRO CE DURE
RANGE: 0.5 - 10 ppm Phosphate (PO4)
1. Fill the test tube (0843) to the mark with the water sample.
2. Use the 1.0 mL pipet (0354) to add 1.0 mL of *Phosphate Acid
Reagent (6282). Cap and mix.
3. Use the 0.1 g measuring spoon (0699) to add one level measure of
*Phosphate Reducing Reagent (6283). Cap and mix until dissolved.
4. Wait 5 minutes for the color to develop. Insert the tube into the
Comparator (3115) and compare the color to the standards to obtain
the result in ppm Phosphate.
11
RANGE: 5-100 ppm Phosphate (PO4) - 1:10 Dilution
1. Use the 1.0 mL pipet (0354) to add 1.0 mL of water sample to the test
tube (0843).
2. Add deionized water from the Demineralizer Wash Bottle (1151) to fill
to the 10 mL mark.
3. Use the 1.0 mL pipet (0354) to add 1.0 mL *Phosphate Acid Reagent
(6282) to the diluted test sample. Cap and mix.
4. Use the 0.1g measuring spoon (0699) to add one level measure of
Phosphate Reducing Reagent (6283). Cap and mix until dissolved.
5. Wait 5 minutes for the color to develop. Insert the tube into the
Comparator (3115).the color to the standards. Multiply the value by
10 to determine the result in ppm Phosphate.
12
REC OM MENDED STAN DARD IZA TION PRAC TICES
The Corrosion Control Kit tests for Alkalinity, Calcium Hardness,
Phosphate, pH, and TDS. This outfit was designed specifically for field
testing purposes. In order to check the performance and accuracy of the
equipment it is recommended that the equipment be checked against
reference standards. Routine performance checks will enable the operator
to keep track of the accuracy and be able to address any problems in the
testing methods or the equipment, and guarantee that the performance
specifications are being achieved.
The age of the reagents can be determined from the lot number, a 6 or 7
digit number found on the reagent bottle. Only the first three digits are
important. The first two digits refer to the week of the year. The third digit
refers to the last digit of the year. For example: 061 would refer to the sixth
week of 2001.
To determine the performance, check for Alkalinity, Calcium Hardness,
and Phosphate. Concentrated standard solutions are available for each
analyte. The operator dilutes the concentrate using good laboratory
practices to a level which can be correctly tested by the method provided.
The concentrated standards are made according to APHA or EPA
specifications, and use reagent grade chemicals to provide the necessary
analyte in a stabilized chemical form.
The electrometric methods for measuring pH and TDS are subjected to the
same type of performance test. The pH Tester is checked against a standard
buffer solution that is provided with the kit. This buffer is prepared from
salts that are traceable to NIST buffers. The TDS solutions are also
prepared from salts that are traceable to NIST standards.
It is a good practice and highly recommended that the operator keep a
journal or log of all performance test results: dates tested, and age of all the
reagents used in the tests. See suggested Log Form.
To conduct performance tests on the equipment and the methods based on
the reference standards, the following recommended procedures are
provided:
ALKALINITY STANDARD · CODE 5168
Fill 100 mL volumetric flask to
to dispense 1.0 mL of standard into flask. Dilute to volume and mix.
1
volume with Deionized water. Use pipet
2
Diluted standard = 100 ppm Total Alkalinity
13
CALCIUM HARDNESS STANDARD · CODE 6185
Fill 100 mL volumetric flask to
to dispense 10 mL of standard into flask. Dilute to volume and mix.
1
volume with Deionized water. Use pipet
2
Diluted standard = 100 ppm Calcium Hardness
PHOSPHATE STANDARD · CODE 6184
Prepare two 100 mL volumetric flasks by filling to
water. Use pipet to dispense 10 mL of standard to first flask. Dilute to
1
volume with distilled
2
volume and mix. Use another pipet to dispense 6 mL from first flask into
second flask. Dilute to volume and mix.
Diluted standard = 6 ppm Phosphate
pH BUFFER 7.0 · CODE 2881
pH Buffer 7.0 is provided with each kit and should be used periodically to
check the performance of the tester. Other buffer solutions can be provided
to cover different pH ranges of interest.
TDS
TDS solutions can be selected from a list of different strengths:
74 MMHOS (52 ppm) – Code 6416
718 MMHOS (503 ppm) – Code 6417
1413 MMHOS (989 ppm) – Code 6354
Following the instructions for the tester, periodically check the response of
the tester to guarantee proper performance.
TEMPERATURE
The thermometer (Code 1066) should be periodically checked against a
reference thermometer that is NIST certified. Any deviation from the
reference temperature should be noted.
14
LAMOTTE COM PANY
Helping Peo ple Solve An a lyt i cal Chal lenges
PO Box 329 · Chestertown · Mary land · 21620 · USA
800-344-3100 · 410-778-3100 (Out side U.S.A.) · Fax 410-778-6394
Visit us on the web at www.lamotte.com
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