Hanna Instruments HI 84431 User Manual

Instruction Manual

HI 84431

TOTAL ALKALINITY

MINITITRATOR & pH METER

for Water Analysis

www.hannainst.com

Dear Customer, Thank you for choosing a Hanna product. This manual will provide you with the necessary

information for the correct use of the instrument. Please read it carefully before using the meter. If you need additional technical information, do not hesitate to e-mail us at tech@hannainst.com.

TABLE OF CONTENTS

PRELIMINARY EXAMINATION................................................................................................. 4

GENERAL DESCRIPTION ........................................................................................................ 4

SPECIFICATIONS ................................................................................................................... 7

PRINCIPLE OF OPERATION .................................................................................................... 8

FUNCTIONAL AND PHYSICAL DESCRIPTION ............................................................................. 9

TITRATOR STARTUP ........................................................................................................... 12

SETUP CONFIGURATION MENU .......................................................................................... 13

ELECTRODE PREPARATION .................................................................................................. 18

ELECTRODE CALIBRATION PROCEDURE................................................................................. 19

pH BUFFER TEMPERATURE DEPENDENCE ............................................................................ 23

PUMP TUBE INSTALLATION ................................................................................................. 24

PURGE .............................................................................................................................. 24

PUMP CALIBRATION PROCEDURE ........................................................................................ 26

TITRATION PROCEDURE ..................................................................................................... 29

pH MEASUREMENT ............................................................................................................ 34

TEMPERATURE CALIBRATION PROCEDURE (for technical personnel only) ............................... 38

TROUBLESHOOTING GUIDE ................................................................................................ 40

ELECTRODE CONDITIONING & MAINTENANCE ...................................................................... 41

ACCESSORIES .....................................................................................................................42

WARRANTY........................................................................................................................43

All rights are reserved. Reproduction in whole or in part is prohibited without the written consent of the copyright owner, Hanna Instruments Inc., Woonsocket, Rhode Island, 02895, USA.

PRELIMINARY EXAMINATION

Please examine this product carefully. Make sure that the instrument is not damaged. If any damage occurred during shipment, please notify your Dealer.

Each HI 84431 minititrator is supplied complete with:

• HI 1131B pH electrode

• HI 7662-M Temperature probe

• HI 84431-50 Titrant low range (100 mL)

• HI 84431-51 Titrant high range (100 mL)

• HI 84431-55 Pump calibration solution (100 mL)

• HI 70004 pH 4.01 buffer solution (2 x 20 mL)

• HI 700083 pH 8.30 buffer solution (2 x 20 mL)

• HI 70010 pH 10.01 buffer solution (2 x 20 mL)

• Two 100 mL beakers

• Tube set with dispensing tip

• Stir bars (medium 2 pcs.)

• 12 Vdc power adapter

• Instruction manual

Note: Save all packing material until you are sure that the instrument works correctly.

Any defective item must be returned in its original packing.

GENERAL DESCRIPTION

The HI 84431 is an easy to use microprocessor-based automatic minititrator and pH meter designed for the rapid and accurate analysis of Total Titratable alkalinity in water. By eliminating subjective factors including color indicators, errors in mathematical calculations or erratic titrant additions from the measurement, the HI 84431 makes Total Titratable alkalinity analysis precisely. This will quickly become a valuable alkalinity analysis tool of waters and wastewaters.

The instrument benefits from Hanna’s many years of experience as manufacturer of quality analytical instruments. A clear and well-designed user interface makes the instrument intuitive and simple to use. A dedicated HELP key aids in set-up, calibration, status and troubleshooting.

By simply pressing START key, the HI 84431 automatically starts pump operation and titrates the sample to the end point. The HI 84431 has a simple and accurate peristaltic pump to ensure the best accuracy and repeatability. By performing pump calibration with the Hanna standard provided, the instrument accuracy is assured.

The instrument employs a powerful and effective built-in algorithm to analyze the pH response to determine the exact pH endpoint, then uses this to make the necessary calculations. The Titratable Alkalinity determination is instantaneously displayed in selected measurement units on the large dot matrix display. The instrument is ready for the next analysis immediately.

Other features:

• Log on demand up to 100 samples (50 for pH measurement; 50 for titration results)

• GLP feature, to view last calibration data for pH electrode and pump

MEASUREMENT SIGNIFICANCE

Water alkalinity is expression of a waters acid-neutralizing capacity and it is determined by titration with standard acid solutions. Alkalinity is an important parameter for control and treatment of potable and wastewaters, because it indicates the water buffering capacity (ability to resist at pH change, primarily because of bicarbonate/ carbonate content). A low water alkalinity signifies that the water is susceptible to pH change and high alkalinity indicates that water is able to resist a major change of pH. Alkalinity can be used to estimate water hardness or to determine water corrosive capacity. Alkalinity of surface water, quantified by mg/L as CaCO

or meq/L, may be caused by carbonate,

bicarbonate, hydroxide, phosphates, borates, silicates or organic acids salts. Conventionally, the water alkalinity is approximated as sum of components. Three types of alkalinities exist together to form total alkalinity:

TA = OH

+ CO

2¯

+ HCO

OH¯ – hydroxide alkalinity

2¯

– carbonate alkalinity

– bicarbonate alkalinity

HCO

TA – total alkalinity Different tests can be performed to determine the quantity of different alkalinities present. A titration to pH 8.3 is considered Strong Alkalinity (SA) and to pH 4.5 Total Alkalinity (TA).

The results of a titration provide a means to classify the principle forms of alkalinity. Relationship of titrant volumes for alkalinity calculations:

stlusernoitartiTHordyedixCobraetanetanobraciB

0=AS00AT

AT=ASAT00

AT2/1<AS0AS2AS2-AT

AT2/1=AS0AT0

AT2/1>ASAT-AS2)AS-AT(20

According to the Standard Methods of Waters and Wastewaters Analysis, there are two options to determine water alkalinity:

1) Strong alkalinity determination by titration of the water sample with strong acid solution to 8.3 pH (known as phenolphtalein alkalinity).

2) Total alkalinity determination by titration of the water sample with strong acid solution to 4.5 pH (known as bromcresol green alkalinity).

Potentiometric end point detection using a pH electrode is more objective than using visual end point determinations with color changing indicators. The HI 84431 minititrator is a potentiometric titrator. The instrument also can be used as a pH meter. The volume of titrant dispensed necessary to reach the end point is then used to calculate the water alkalinity expressed in mg/L as CaCO meq/L as CaCO3.

Interferences:

• dissolved gases, lost or gained during samples storage or transport can modify the

alkalinity of the samples;

• presence in the samples of the: precipitates, solid suspensions, oils, soaps can coat a pH

electrode;

To eliminate or diminish the interference effects, it is recommended:

• to protect the samples against the atmospheric action (store in an airtight vessel);

• to avoid vigorous shaking or mixing: stir gently;

• maintenance of the pH electrode (see section Electrode Conditioning and Maintenance)

SPECIFICATIONS

Titrator Range Titratable alkalinity (low range)

mg/L

: 15.0 - 500.0 mg/L as CaCO

meq/L : 0.3 - 10.0 meq/L as CaCO Titratable alkalinity (high range) mg/L : 400 - 4000 mg/L as CaCO meq/L : 8 - 80 meq/L as CaCO

Resolution Titratable alkalinity (low range):

0.1 mg/L

0.1 meq/L Titratable alkalinity (high range): 1mg/L

1meq/L Accuracy 5% of reading Titration method Acid-base titration (total alkalinity / strong alkalinity) Principle End point titration: 4.50 pH / 8.30 pH Pump debit 0.5 mL/min Stirring speed 600 rpm Log data Up to 50 samples

pH meter pH meter -2.0 to 16.0 pH / -2.00 to 16.00 pH

pH Resolution: 0.1 pH / 0.01 pH pH Accuracy: ± 0.01 pH pH Calibration: 1, 2 or 3 calibration points;

3 available buffers (4.01; 8.30; 10.01) Temperature manual or automatic from compensation: -20 to 120 °C (-4 to 248 °F) Log data Up to 50 samples

Temperature Range -20.0 to 120.0 °C (-4.0 to 248.0 °F)

Resolution 0.1 °C Accuracy ±0.4 °C without probe error

Electrode HI 1131B (included) Temperature Probe HI 7662-M (included) Environment 0 to 50 °C (32 to 122 °F); max 95% RH non-condensing Power supply 12 Vdc power adapter Dimensions 208 × 214 × 163 mm (8.2×8.4×6.4”) (with beaker) Weight 2200 g (77 oz.)

REQUIRED REAGENTS Code Description Quantity/Test HI 84431 - 50 Titrant (Low Range) 1 mL

HI 84431 - 51 Titrant (High Range) 1 mL HI 84431 - 55 Pump Calibration Solution 2 mL for low range

20 mL for high range

PRINCIPLE OF OPERATION

Water alkalinity determination is performed by titration with acid reagent to pH end point. Alkalinity is expressed as:

• Strong alkalinity (phenolphtalein alkalinity) determination by titration at 8.3 pH (in this reaction hydroxide ions are converted to water and carbonate ions to bicarbonate ions):

+ H2SO4 → 2H2O + SO

2HO

2¯

2CO

+ H2SO4 → 2HCO3 + SO

Since bicarbonate ions can be converted to carbonic acid with additional sulfuric acid, the phenolphtalein alkalinity measure total hydroxide ions and one half of the bicarbonate ions contribution.

• Total alkalinity determination by titration at 4.5 pH (completly convert of the bicarbonate ions):

+ H2SO4 → 2H2CO3 + SO

2HCO

It is important that the samples are protected against atmospheric factors (store them in sealed bottles that are completely filled) and avoid vigorous shaking, mixing and long exposure to air. The HI 84431 minititrator is designed to determine the alkalinity of waters by potentiometric titration in a low range (10-500mg/mL as CaCO3) and in a high range (400-4000mg/mL as CaCO3). Selection of the alkalinity range is limited by the pH sample: if the measured pH is greater than 8.3 both total and strong alkalinity can be determined. If the sample pH is lower than 8.3 only total alkalinity can be determined. The HI 84331 utilizes two different titration solutions to cover the entire measurement range. If the range is changed, the titrant must be changed and the peristaltic pump must be primed and recalibrated. HI 84431-55 is used for pump calibration; the volume used will vary for the selected range. Titratable Alkalinity in waters, as performed on the HI 84431 minititrator, utilizes a simple sample preparation, a high quality peristaltic dosing pump for titrant, potentiometric endpoint detector and instantaneaous computations. To maintain the high precision of the titrator, a simple pump calibration procedure is required. The calibration involves the analysis of a known volume of a known solution (standard provided) and compensates for changes in pump dosing that may occur due to many factors including tube stretching or aging. This procedure should be performed regularly.

2¯

FUNCTIONAL AND PHYSICAL DESCRIPTION

OVERHEAD VIEWOVERHEAD VIEW

OVERHEAD VIEW

OVERHEAD VIEWOVERHEAD VIEW

1. Titrant bottle

2. Graphic LCD

3. Keypad

4. Dedicated guide tube for Temperature Probe

5. Electrode holder

6. Dedicated guide tube for titrant tip

7. Peristaltic pump tube

FRONT VIEWFRONT VIEW

FRONT VIEW

FRONT VIEWFRONT VIEW

REAR VIEWREAR VIEW

REAR VIEW

REAR VIEWREAR VIEW

8. Temperature probe

9. pH Electrode

10. Beaker

11. BNC electrode connector

12. Temperature probe socket

13. Power switch

14. Power adapter connector

15. Peristaltic pump

KEYPAD FUNCTION AND INDICATORS

ESC - used to leave the current screen and to return either to the previous screen or to the

main screen. When pressed while modifying a parameter within the SETUP menu, exits parameter without changing it.

- used to modify the parameters’ values, to scroll the information displayed while

viewing a help or to move between the options from the instrument’s SETUP

HELP - used to access/leave the instrument’s contextual help MENU - used to enter SETUP, Recall or GLP selection menu, while instrument is in pH or

Titration main screen

STIR - used to start/stop the stirrer. Note: The stirer starts automatically during pump calibration and titration and cannot be

stopped by pressing STIR key.

GUIDE TO INDICATORS

During the instrument’s operation information is displayed on the LCD. Displayed icons:

Unstable reading. Stirrer on.

Pump running.

Parameter can be changed.

1. Current time and instrument mode information (pH meter or Titrator)

2. pH electrode condition information

3. Main reading information

4. Instrument status information

5. Functional key area

6. Indicates that the displayed value can be changed using ARROW keys

7. Temperature value (

°C, °F)

8. pH temperature compensation mode (Manual or Automatic)

9. Stirrer and reading status area

PERISTALTIC PUMP

Peristaltic pumps are self priming. Liquid never contacts the pump components. The titrant tubing is pressed along the rotating rollers of the pump. The rollers compress the tubing, driving the titrant to the dispensing tip.

TITRATOR STARTUP

This is a general outline of the steps required to make a titration. The following sections expand upon each section.

• Place the instrument on a flat table. Do not place the instrument in direct sun light.

• Connect the power adapter to the instrument.

• Turn the instrument ON using the power switch from the rear panel of the instrument.

• Set up the instrument. See the “Setup Configuration Menu” section for details.

• Connect the pH sensor and temperature probe to the instrument.

• Calibrate the pH electrode. At least a single point calibration is necessary for titration.

• Place the peristaltic pump tube on the pump (inlet tube is connected with the reagent bottle, outlet tube is connected with the dosing tip). See the “Pump Tube Replacement” section for the procedure.

• Remove the reagent bottle cap and replace the bottle cap with the tubes. Place the reagent bottle in the appropriate place on the titrator top (pay attention to the titration range).

• Purge the titrant.

• Calibrate the pump.

• Prepare the sample.

• Run a titration and log sample results.

SETUP CONFIGURATION MENU

The titrator’s setup configuration menu may be accessed from the pH or titration screens by pressing the MENU key, then Setup.

A list of setup parameters will be displayed with currently configured setting. While in the setup menu it is possible to modify the instrument’s operation parameters. The

ARROW keys permit the user to scroll the setup parameters. Press HELP to view the contextual help. Press ESC to return to the main screen.

Concentration unit

Options: mg/L, meq/L.

Press the corresponding function key to change the option.

Alkalinity type

Options: Total LR (total alkalinity low range)

Total HR (total alkalinity high range) Strong LR (strong alkalinity low range) Strong HR (strong alkalinity high range)

Press the corresponding function key to change the option.

From your knowledge of expected concentrations, use the table below to determine which settings and solutions are appropriate:

AtinilaklepyTyRLlatoTlatoTRHRLgnortSRHgnortS

L/gmegnartnemerusaeMOCaC

L/qem3OCaC 001-2.0.08-801-2.0.008-8

)M55-13448IH(noitulosnoitarbilacpmuP Lm220LmLm2Lm02

qertnartiT05-13448IH15-13448IH05-13448IH15-13448IH

deriu

)Lm(eziselpmaS 05Lm05Lm05Lm05Lm

elpmasfoHpmuminiM 5.4>5.4>3.8>.8>3

tartitfotniopdnE Hp5.4Hp5.4Hp3.8Hp3.8

noi

005-010004-004005-010004-004

Use Total LR or Strong LR for waters alkalinity in the 10 - 500 mg/L range. Use Total HR or Strong HR for waters alkalinity in the 400 - 4000 mg/L range. Use the appropriate titrant for each range. Also, the pump must be recalibrated when the measurement range is changed (see table above).

Calibration timeout

pH resolution

Options: Disabled or 1 to 7 days.

This option is used to set the number of days before the pH calibration expired warning message is flagged.

Press Modify to access the calibration timeout value modify parameter.

Use the ARROW keys in order to increase/decrease the value.

Press Accept to confirm or ESC to return to the setup menu without saving the new value.

Options: 0.1, 0.01. Press the displayed function key in order to change

the pH resolution.

Temperature unit

Backlight

Options: °C, °F.

Press the function key in order to change the temperature unit.

Options: 0 to 8. Press Modify to access the backlight level.

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