Yokogawa PH72 User Manual

User’s Manual

Model PH72 Personal pH/ORP Meter

IM 12B03D02-01E

3rd Edition

Preface

Thank you for purchasing the Model PH72 Personal pH/ORP Meter. Please read this manual thoroughly before using the meter.

The following symbol marks are used for safety precautions in this manual.

Preface

WARNING

CAUTION

: Indicates that serious injury may result, if the user fails to

follow instructions.

: Indicates that minor injury to personnel, or damage to the

equipment, may result if the user fails to follow instructions.

WARNING

Do NOT use this instrument where there is a possibility of electrical shock. Do NOT touch any part of the electrode immediately after using in very hot liquids —

otherwise, you may get burned.

CAUTION

Do not apply physical shock or excessive force to the glass sensor, or it may break. If the meter will not be used for an extended period of time, be sure to remove the

batteries. Otherwise battery leakage may occur, causing damage to or malfunction of the meter.

The contents of this manual are subject to change without prior notice. Yokogawa Electric Corporation assumes no liability for damage, defects, or loss of the

product caused by any of the following:

Misuse by the user; Inappropriate or out-of-specifications use of the product; Use in an unsuitable environment; Repair or modification of this or related products by persons other than Yokogawa-

authorized engineers.

Preface

Liquid Crystal Display (LCD) Characters

On the LCD alphanumeric characters are displayed as follows.

Alphabet

Display

Alphabet

Display DisplayNumerals

All display segments

Note Regarding Panels Shown in this Manual:

Panels shown in this manual should be regarded as examples. Actual panel format may vary depending on parameter settings and on type of connected sensor.

Flashing Displays

Flashing messages, numbers and digits on the display are indicated in gray in this manual.

F00.EPS

Flashing state: Lit state:

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Warranty and Service

Yokogawa products and parts are guaranteed to be free from defects in workmanship and materials under normal use and service for a period of (typically) 12 months from the date of shipment from the manufacturer.

Individual sales units may offer different warranty periods, so the original purchase order should be consulted for the conditions of sale. Damage caused by normal wear and tear, inadequate maintenance, corrosion, or due to chemical processes, is excluded from this warranty coverage.

In the event of a warranty claim, any items that are considered to be defective should be sent (freight paid) for repair or replacement (at Yokogawa discretion) to the service department of the relevant sales unit. The following information must be included in a letter accompanying the returned items:

Model code and serial number Copy of original purchase order showing the date Length of time used, and the measuring environment Fault symptoms, and circumstances of failure Statement whether service under warranty or out-of-warranty service is requested Complete shipping and billing instructions for return of goods, plus the name and

phone number of a contact person who can be reached for further information

Goods that have been in contact with process fluids must be decontaminated / disinfected before shipment, and a statement to this effect should be included. Safety data sheets for all process components that the goods have exposed to should also be included.

Preface

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Contents

CONTENTS

Preface...................................................................................................................... 1-1

1. Outline ................................................................................................................. 1-1

1.1 Features ......................................................................................................................... 1-1

1.2 Specifications ................................................................................................................. 1-2

1.3 When You Receive the PH72 Meter Package .............................................................. 1-3

1.4 PH72 Meter Kit .............................................................................................................. 1-4

1.5 PH72 Meter — Part Names and Functions .................................................................. 1-5

1.6 Sensors — Types, Part Names and Functions............................................................. 1-6

1.7 Options (Available Separately) ...................................................................................... 1-8

1.8 Spare Parts .................................................................................................................... 1-9

2. Preparation.......................................................................................................... 2-1

2.1 Installing the Batteries ................................................................................................... 2-1

2.2 Connecting the Sensor Cable ....................................................................................... 2-2

2.3 Setting the Date and Time ............................................................................................ 2-3

2.4 Selecting pH or ORP Measurement .............................................................................. 2-4

2.5 Wetting Cap ................................................................................................................... 2-4

2.6 Manual Temperature Setting ......................................................................................... 2-5

2.7 pH Calibration ................................................................................................................ 2-5

3. Measurement ...................................................................................................... 3-1

3.1 Precautions .................................................................................................................... 3-1

3.2 Measurement Procedures ............................................................................................. 3-2

3.3 Measurement Display Panel.......................................................................................... 3-3

3.4 Saving a Measured Value ............................................................................................. 3-3

4. Calibration ........................................................................................................... 4-1

4.1 Automatic Calibration..................................................................................................... 4-3

4.2 Manual Calibration ......................................................................................................... 4-6

5. Keypad and Display Functions ......................................................................... 5-1

5.1 Keypad Functions .......................................................................................................... 5-2

5.2 Display Items ................................................................................................................. 5-4

5.3 Function Mode ............................................................................................................... 5-5

6. Maintenance ........................................................................................................ 6-1

6.1 For Optimum Meter Performance.................................................................................. 6-1

6.2 pH Electrode Cleaning................................................................................................... 6-2

6.3 Sensor Replacement ..................................................................................................... 6-3

6.4 Rehydrating the Glass Electrode................................................................................... 6-3

6.5 Replenishing the Electrode with Filling Solution (KCl solution) .................................... 6-4

6.6 Cleaning and Drying Connectors .................................................................................. 6-5

6.7 Storage and O-ring/Gasket Replacement ..................................................................... 6-6

7. Troubleshooting ................................................................................................. 7-1

7.1 Causes of Abnormal Readings and Errors ................................................................... 7-1

7.2 Error Messages, Possible Causes, and Corrective Actions ......................................... 7-2

7.3 Causes of Abnormal Measured Values......................................................................... 7-5

7.4 Other Conditions ............................................................................................................ 7-6

8. ORP Meter ........................................................................................................... 8-1

8.1 ORP Measurement ........................................................................................................ 8-1

8.2 Maintenance of ORP Sensors ....................................................................................... 8-2

8.3 Checking the ORP Sensor ............................................................................................ 8-3

9. Technical Information......................................................................................... 9-1

9.1 Measurement Principle of pH Meter (Glass Electrode Method) ................................... 9-1

9.2 Relationship between EMF of Glass Membrane and pH Value ................................... 9-2

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Contents

9.3 Temperature Compensation .......................................................................................... 9-4

9.4 The Asymmetry Potential .............................................................................................. 9-5

9.5 The Alkaline Error .......................................................................................................... 9-6

9.6 The Acid Error ............................................................................................................... 9-7

9.7 Calibration Calculation ................................................................................................... 9-8

9.8 ORP (Oxidation-Reduction Potential) ............................................................................ 9-9

9.9 Reference Electrode .................................................................................................... 9-10

9.10 Wetted Part Materials of Sensors ............................................................................. 9-12

9.11 References................................................................................................................. 9-12

Appendix ..................................................................................................................... 1

MSDS (Material Safety Data Sheet) ............................................................... MADS-1

Revision Record .......................................................................................................... i

IM 12B03D02-01E

Contents

IM 12B03D02-01E

1. Outline

The Model PH72 Personal pH/ORP Meter is a highly accurate, portable pH meter for laboratory and field application. With its self-diagnostic function, the PH72 provides precise measurement of pH and ORP (oxidation-reduction potential). Measurement results can be stored and stored data can be checked on the meter display any time. The PH72 meter is of waterproof construction so that it can safely be used outdoors on a rainy day, and can also withstand being accidentally dropped into water.

1.1 Features

Water r esistant case

When this meter is used with its dedicated sensor, it meets the requirements of class IP67 according to “Degree of Protection Provided by Enclosure” in IEC 60529.

Simple calibration

Automatic calibration based on preprogrammed data of standard solutions or manual calibration can be done through simple key operations.

Calendar and clock function

Internal clock functions allow “one-touch checking” of measurement date and time.

Data storage function

Up to 300 measured pH values along with their respective solution temperatures, dates and times, can be stored and stored data can be checked on the display any time.

Auto power off function

The meter will turn off power automatically if not operated during a preset time period. The auto power off time can be user configurable in the range of 1 to 120 minutes in increments of 1 minute. The auto power off function can be disabled, where the meter should be used with care to conserve the batteries.

Alarm clock function

The meter can issue an alarm signal at a specified time. Even when meter power is turned off, the internal clock can issue an alarm signal.

Self-diagnostic function

A relevant error message will appear based on the self-diagnostic function.

Large, clear LCD

A measured pH (mV) value, solution temperature, date and time are clearly viewed on the display.

Compact, lightweight, and handy

The meter fits comfortably your hand and also stands firm on the table.

1. Outline

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1-1

1. Outline

1.2 Specifications

Measuring range: pH: 0 to 14 pH*

ORP: -2000 to 2000 mV Temperature: 0 to 1008C*

Resolution: pH: 0.01 pH

ORP: 0.1 mV (-199.9 to 199.9 mV)

1 mV (-2000 to -200 mV and 200 to 2000 mV)

Temperature: 0.18C

Repeatability (without sensor): pH: 60.01 pH 61 digit

ORP: 61 mV 61 digit

Accuracy (Temperature): 60.78C (0 to 708C)

618C (above 708C)

Temperature compensation (glass electrode emf — temperature characteristics):

Automatic compensation (or manual compensation*1)

Solution temperature: 0 to 808C (or 0 to 1008C*3) (0 to 508C when a KCl replenish-

free type sensor and its sensor cable are immersed in water) Solution conductivity: 50 mS/cm or more Ambient temperature: 0 to 508C Construction: Protection class IP67 (IEC 60529) Power source: 2x AA batteries (LR6)

Auto power off function (time configurable: 1 to 120 minutes) Battery life: Approximately 600 hours*4 of continuous use (battery type and

operating condition dependent) Dimensions: Approximately 150(H) x 61(W) x 42(D) mm (not including

connector part) Weight: Approximately 220 g (including batteries) EMC Conformity Standards: EMI (Emission) EN 61326-1 Class B

Test Item

Electromagnetic radiation disturbance

EMS (Immunity) EN 61326-1 Table 2 (For use in inductrial locations)

Test ItemNo.

Electrostatic

discharge

RF amplitude

modulated electromagnetic field

* A: Normal performance within the specification limits: ±20% of the measured value. B: Temporary degration or less of function or performance which is self-recoverable. ** Display value may be affected by strong electromagnetic field.

Test Specification Basic Standard

4 kV (contact) 8 kV (air)

80 to 1000 MHz, 10 V/m (unmodulated) 80% AM (1 kHz)

1.4 to 2.0 GHz, 10 V/m (unmodulated)

80% AM (1 kHz)

2.0 to 4.0 GHz,

3 V/m (unmodulated) 80% AM (1 kHz)

*1: Display range is from -2 to 10 pH. *2: Display range is from-10 to 1208C. *3: When a needle type or test tube size pH sensor is used. *4: When alkaline batteries are used.

1-2

Frequency Range

30 to 1000 MHz

IEC 61000-4-2

IEC 61000-4-3

CISPR 16-1 and 16-2

Basic Standard

T0101.EPS

Performance

Criteria*

B**

T0102.EPS

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1.3 When You Receive the PH72 Meter Package

Confirm that you received all package components of the PH72 meter you ordered referring to the Model and Suffix Code and the item list in Section 1.4, “PH72 Meter Kit.” Carefully inspect the meter and sensor, referring to Section 1.5, “PH72 Meter — Part Names and Functions” and Section 1.6, “Sensors — Types, Part Names and Functions.” Particular attention should be taken:

• Not to lose a wetting cap attached on the sensor tip. This cap is needed for storage.

• Not to twist or pull the cable.

• Not to hit or drop the meter.

• Not to get connectors dirty.

• In handling of standard solutions and reagents. Solution bottles should be stored in a cool, dark place and tightly capped after use. Once opened, the contents of a bottle should be used early. Dispose of solutions in accordance with local regulations.

1. Outline

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1-3

1. Outline

1.4 PH72 Meter Kit

8 11

Instrument Card

Quick Manual

No.

Item

Personal pH/ORP meter

Dry batteries, 2x AA batteries

User's Manual and Quick Manual

Non-slip pads (2 pcs)

Hand strap

Instrument Card

KCl replenish-free type pH sensor

KCl refillable type pH sensor

Needle type pH sensor

Test tube size pH sensor

KCl refillable type ORP sensor

Cotton swabs for sensor cleaning

pH 4 standard solution (50 ml)

pH 7 standard solution (50 ml)

Calibration bottles (2 bottles)

KCl filling solution (3.3 mol/l, 50 ml)

Syringe (5 ml)

13 14

PH4

PH7

KCl

1-4

Model Suffix Code

PH72

Sensors -00

-11

-13

-21

-23

-32

-33

-41

-43

-51

Label -J language -E

- -AA Note: On the name plate of sensor, Model and Suffix Code of sensor itself (PH72SN- -AA or

OR72SN- -AA) is indicated. (See Section 1.6.)

Specification

Personal pH/ORP meter Without sensor

With KCl replenish-free type combination pH sensor (cable length: 0.75 m) With KCl replenish-free type combination pH sensor (cable length: 3 m)

With KCl refillable type combination pH sensor (cable length: 0.75 m) With KCl refillable type combination pH sensor (cable length: 3 m)

With needle type pH sensor (cable length: 0.75 m) With test tube size pH sensor (cable length: 0.75 m) With KCl refillable type ORP sensor (cable length: 0.75 m) With KCl refillable type ORP sensor (cable length: 3 m) With KCl refillable type combination pH sensor (cable length:

0.75 m) + KCl refillable type ORP sensor (cable length: 0.75 m) Japanese English

Always -AA

Items Included

1 to 6 in common, plus: None

7, 12, 13, 14, 15 7, 12, 13, 14, 15

8, 12, 13, 14, 15, 16, 17 8, 12, 13, 14, 15, 16, 17

9, 12, 13, 14, 15, 16, 17 10, 12, 13, 14, 15, 16, 17 11, 12, 16, 17 11, 12, 16, 17 8, 11, 12, 13, 14, 15, 16, 17

F010401.EPS

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1.5 PH72 Meter — Part Names and Functions

1. Outline

O-ring

Sensor cable connector

Connection to a dedicated pH (ORP) sensor.

Hand strap attachment points

Display

pH (mV) and temperature

simultaneously.

Keypad

PERSONAL

pH/ORP METER

PH72

MODEL

S1.0

STYLE No.

E000001

2004.

Battery box cover fixing screw

Name plate

F010501.EPS

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1-5

1. Outline

1.6 Sensors — Types, Part Names and Functions

Sensors available for use with the Model PH72 Personal pH/ORP Meter are: generalpurpose pH sensors (KCl replenish-free and KCl refillable types), needle type pH sensor, test tube size pH sensor, and KCl refillable type ORP sensor. Check the Model and Suffix Code on the name plate to identify the type of your sensor.

Example of Name Plate

STYLE

MODEL

PH72SN

SUFFIX NO.

Model and Suffix Code for pH and ORP Sensors

Specification

PH72SN

-11

-13

-18

-19

-21

-23

-28

-32

-33

-38

-39

-AA

Model Suffix Code

OR72SN

-41

-43

-48

-49

-AA

: Part number of PH81, PH82 (previous models).

: Waterproofing is not guaranteed if you use PH82-type sensor in conjunction with PH72 meter.

pH sensor for Personal pH/ORP meter

For PH71, PH72; KCl replenish-free type combination pH sensor (cable length: 0.75 m) For PH71, PH72; KCl replenish-free type combination pH sensor (cable length: 3 m) For PH81, PH82; KCl replenish-free type combination pH sensor (cable length: 0.75 m) For PH81, PH82; KCl replenish-free type combination pH sensor (cable length: 3 m)

For PH71, PH72; KCl refillable type combination pH sensor (cable length: 0.75 m) For PH71, PH72; KCl refillable type combination pH sensor (cable length: 3 m) For PH81, PH82; KCl refillable type combination pH sensor (cable length: 0.75 m)

For PH71, PH72; needle type pH sensor (cable length: 0.75 m) For PH71, PH72; test tube size pH sensor (cable length: 0.75 m) For PH82; needle type pH sensor (cable length: 0.75 m) For PH82; test tube size pH sensor (cable length: 0.75 m) Always -AA

Specification ORP sensor for Personal pH/ORP meter

For PH72; KCl refillable type ORP sensor (cable length: 0.75 m) For PH72; KCl refillable type ORP sensor (cable length: 3 m) For PH82; KCl refillable type ORP sensor (cable length: 0.75 m) For PH82; KCl refillable type ORP sensor (cable length: 3 m) Always -AA

S1.0

000001-11-AA

Made in Japan

RemarksModel Suffix Code

K9220YA

K9220YB

K9220YC

K9220YG

K9220YJ

Remarks

K9220YL

F010601.EPS

1-6

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KCl replenish-free type combination pH sensor

PH72 - 11 - - AA PH72 - 13 - - AA

Name plate

( PH72SN-11-AA, PH72SN-13-AA )

Waterproof cover

Prevents water ingress that may cause insulation failure.

Connector

Connection to pH/ORP meter.

Glass electrode

Measures pH

values.

Protective cover

Removed only during cleaning.

Liquid junction

Provides electrical contact between internal reference electrode and sample solution.

Temperature element

Wetting cap

Used to prevent glass electrode from dying out. During storage this cap

*1: On the name plate of sensor, Model and Suffix Code of sensor itself (PH72SN- -AA or OR72SN- -AA) is indicated. (See Section 1.6.)

with cotton wad moistened with water should be attached to electrode tip.

Sensor cable

Sensor body

Plastic body that can withstand temperature up to 80°C.

Glass electrode

(Platinum electrode)

KCl refillable type combination pH sensor, ORP sensor

PH72 - 21 - - AA PH72 - 23 - - AA PH72 - 41 - - AA

Name plate

( PH72SN-21-AA, PH72SN-23-AA, OR72SN-41-AA, OR72SN-43-AA )

Connector Sensor grip

Wetting cap

Sensor body

Temperature element

Protective cover

PH72 - 43 - - AA PH72 - 51 - - AA

Waterproof cover

Fill hole plug

Liquid junction

Fill hole for KCl filling solution

Measures solution temperature and compensates for temperature effect on pH electrode.

3.3 mol/l KCl solution is used.

Sensor cable

Sensor grip

Prevents filling solution from

leaking from fill hole during storage. Always unplugged during measurement.

1. Outline

F010602.EPS

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1-7

1. Outline

1.7 Options (Available Separately)

The following options are available for the Model PH72 Personal pH/ORP Meter for your convenience. When ordering, specify the part number.

pH 9 Standard solution

(Part no. : K9220XF)

Used for calibration when anticipated pH value of sample solution is alkaline. (50ml)

Soft carrying case

(Part no. : B9269KJ)

Unit: mm

Approx. 280

Approx. 140

A soft black carrying case holds

pH/ORP meter and sensor.

Approx. 30

Sensor stand

(Part no. : K9220XN)

Holds a sensor when pH/ORP meter is used on the table. Made of rustproof stainless

steel.

F010 701 .EPS

1-8

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1.8 Spare Parts

1. Outline

pH 4 Standard solution

(Part no. : K9084KF)

Used for calibration. (250 ml)

KCl solution

(Part no. : K9220XH)

Used to replenish KCl refillable type sensor. 3.3 mol/l, 2 bottles x 50 ml

pH 7 Standard solution

(Part no. : K9084KG)

Used for calibration. (250 ml)

Quinhydrone reagent (Part no. : K9024EC)

Used to check ORP electrode. 3 packs, one pack for 250 ml solution.

pH 9 Standard solution

(Part no. : K9084KH)

Used for calibration. (250 ml)

Calibration bottle

(Part no. : K9220WW)

Used during calibration. 2 10-ml bottles.

2 gaskets for battery box 2 O-rings for connector

IM 12B03D02-01E

O-ring and gasket set

(Part no. : K9654AY)

Cap set

(Part no. : K9220ZY)

Used for sensor. 1 protective cover 1 wetting cap

F010801.EPS

1-9

1. Outline

O-rings and gaskets are important parts to ensure that the PH72 meter is water resistant. Replace these parts as required. Refer to Section 6.7, “Storage and O-ring/Gasket Replacement” for replacement.

1-10

IM 12B03D02-01E

2. Preparation

2.1 Installing the Batteries

Install the batteries first.

CAUTION

Select a relatively moisture-free location when installing batteries in the meter. When installing batteries, observe correct polarity (battery orientation). Failure to do so

may damage to the meter. Remove batteries from the meter if it is to be stored for an extended period of time. Do not leave dead batteries in the meter. They may leak and cause meter failure or

erratic operation of the meter. When replacing batteries, replace both batteries at the same time. If only one battery is

replaced, the new battery may discharge into the old battery, which may leak chemicals and damage the meter.

If the battery box gasket is damaged or dirty then the unit may no longer be waterproof; replace the gasket in this case.

(1) Loosen the screw holding the battery

box cover using a coin or similar object.

(2) Remove the battery box cover, and

then install the batteries observing polarity diagram inside.

(3) Make sure the gasket on the inside

458 or more

Batteries

Gasket

Press with your fingers

rim of the battery box is free of foreign material.

(4) Put the cover back on. Insert the tabs

on the top of the cover into the slots at an angle of at least 458 and lower the cover into position.

(5) Press the both ends of the cover down

with your fingers and tighten the screw to fix the cover onto the unit using a coin or similar object.

Note: Do not attempt to tighten further

when you feel resistance before the cover is fastened in place. Loosen the screw once and retighten.

2. Preparation

IM 12B03D02-01E

F020101.eps

2-1

2. Preparation

2.2 Connecting the Sensor Cable

Connect the sensor cable.

CAUTION

Connect the sensor cable in a place free from moisture. When connecting the sensor cable, tighten by turning only the silver locknut, do not turn

the cable or waterproof cover. Also take care not wet or contaminate the connector. Sensors for the PH81 or PH82 meters can be connected. When used in conjunction with

the PH72 meter, however, water resistance is not guaranteed. This is due to the different construction of the connector cover.

(1) Pull the waterproof cover along the

sensor cable away from the connector to expose the locknut.

(2) Connect the connector to the meter

body*. Then tighten firmly by turning only the locknut.

* Align the slots of the sensor cable

connector with the posts of the connector on the meter.

(3) Move the waterproof cover toward

the connector until it contacts with the O-ring* on the meter body.

* Make sure that the O-ring is free of

foreign material.

(4) Push and rotate the waterproof cover

1/4 turn (90 degrees) clockwise to lock into place.

(2)

Waterproof cover

O-ring

(3)

Locknut (Silver)

(1)

(4)

F020201.eps

Note: It is recommended that the sensor be kept connected to the meter to avoid

contamination of the connectors.

2-2

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2.3 Setting the Date and Time

After installing the batteries, set the date and time. Note that if the power is turned off before completing minute setting, start with the date setting when you turn on the power next time. By replacing the batteries, the date setting is not affected but the time setting is. So the time must be reset.

Note: If a sensor cable is not connected to the meter, fluctuating readings or an error

message may appear. Before pressing been connected.

• Setting Procedure

After installing the batteries, press and hold LCD segments appears momentarily and then the date setting display starts

automatically. Set year, month, day, hours, and minutes following the flowchart below. Note: If you attempt to abort the setting procedure before completing, the meter will

beep three times and reject the attempt. Continue until the minute setting is completed.

POWER

Press

for at least 1 sec.

POWER

key, make sure that a sensor has

POWER

key for at least one second. All

2. Preparation

Day setting Hour setting (24-hour format)

IM 12B03D02-01E

Year setting

After several seconds

F/ENT

to set

F/ENT F/ENT

to confirm

F/ENT

to set

After several seconds

F/ENT

to confirm

Month setting

to set

Minute setting

to set

F020301.EPS

2-3

2. Preparation

2.4 Selecting pH or ORP Measurement

Upon completing the date and time setting, the meter is ready for pH measurement. The display shows a pH value with a “pH” unit to the left of the value.

To use the meter for ORP measurement, make sure that an ORP sensor is connected to the meter. Then, change the display for ORP measurement following the procedure described in Section 5.3 (3), “Set measurement unit (PV.U) panel.” The display should show a “mV” unit at the lower right beneath a value when the meter is ready for ORP measurement.

2.5 Wetting Cap

The glass electrode should be kept wet during storage. If the glass electrode dries out, it will take hours to rehydrate and in the meantime the meter may give erroneous readings. The wetting cap is used to prevent the glass electrode from drying out. Sensors are shipped with a wetting cap containing a cotton wad moistened with a few drops of water. For storage replenish the cap with a few drops of water (tap water) and attach to the sensor firmly.

Protective cover

Lug

Slot

Figure 2.1 Wetting Cap

To remove cap, rotate counterclockwise and pull out until lugs on cap clear protective cover through slots.

Removed cap can be attached onto sensor cable during measurement.

F0201.EPS

2-4

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2.6 Manual Temperature Setting

If a sensor without a built-in temperature element (needle type or test tube size pH sensor) is connected to the meter, mark will appear on the display. In this case, measure the temperature of the solution being measured and manually set the measured temperature into the PH72 meter for reliable measurement. The procedure is described in Section 5.3 (2), “Manual temperature setting (M.tP) panel.”

Temperature compensation is performed based on a temperature shown on the display of the PH72 meter. If a temperature shown on the display is different from the actual temperature of the sample being measured, the displayed measured value may not be true. The bigger the difference between the temperature displayed on the meter and the actual temperature of the solution, the bigger the error between the displayed measured value and the true value.

If mark appears on the display even though a sensor with a built-in temperature element is connected, refer to Section 7.4.

2.7 pH Calibration

The PH72 meter needs to be calibrated:

• when the sensor is connected for the first time;

• after the sensor is replaced;

• after the meter has been stored for a long period;

• after the electrode is cleaned; or

• when necessary. The calibration procedure is described in Chapter 4, “Calibration.” Note: Calibration results are saved in the meter when the batteries are replaced.

2. Preparation

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2-5

2. Preparation

2-6

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3. Measurement

3.1 Precautions

(1) After storage for an extended period of time, it is recommended that the meter

should be calibrated before taking measurements.

(2) When using a KCl refillable type sensor, check the level of filling solution. (Refer

to Section 6.5.)

(3) Do not use the meter in a solution with the temperature exceeding 808C (1008C for

the needle type and test tube size pH sensors). When a KCl replenish-free type sensor is used and its sensor grip is immersed, the temperature of the solution should not exceed 508C. Also, do not use the meter in strongly corrosive solutions, such as a solution containing hydrofluoric acid.

(4) Remove stains from the PH72 meter body using a soft cloth or tissue. If necessary,

use a neutral detergent.

(5) If an abnormal symptom occurs during measurement, locate the cause of the

problem and take corrective actions referring to Chapter 7, “Troubleshooting.”

(6) After measurement, rinse off dirt or the sample solution from the sensor with water

and store it. (Refer to Chapter 6, “Maintenance.”)

(7) Keys should be operated by fingers.

Using the PH72 Meter on a Table

The meter is designed as a portable instrument; however, to use it on a table, attach nonslip pads (supplied with the instrument) at top and bottom of the meter to stop it from moving when the sensor is moved.

3. Measurement

IM 12B03D02-01E

Non-slip pads

PERSONAL

pH/ORP METER

MODEL

PH72

STYLE

S1.0

No.

E000001

2004.

F0301.EPS

Figure 3.1 Position of Non-slip Seats

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3. Measurement

3.2 Measurement Procedures

Immersing the sensor

Immerse the sensor so that the protective cover part goes under the sample solution level. The sensor does not need to be immersed deeply.

When using a KCl refillable type sensor, the filling solution level must be above the level of solution being measured. This is to prevent the KCl filling solution from being mixed with the sample solution.

Fill hole (left open during measurement)

Level of filling solution

Level of sample solution

(refill when level is low)

Sample solution

KCl refillable type sensor must be immersed so filling solution level is above the level of sample solution.

Protective cover

F0302.EPS

Figure 3.2 How to Immerse the KCl Refillable Type Sensor

Bubbles trapped in the glass electrode tip may interfere with accurate measurement. Before taking measurements, check the electrode tip for bubbles. If present, gently shake the sensor, as shown in Figure 3.3, to dislodge bubbles from the tip.

Enlarged View of A

* No bubbles

Bubbles

allowed in tip.

Filling solution

F0303.EPS

Filling solution

Glass electrode tip

Figure 3.3 How to Dislodge Bubbles from Glass Electrode Tip

3-2

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3.3 Measurement Display Panel

When immersing the sensor in a sample solution, a measured pH (or mV) value will be shown on the display. There are three types of measurement display panels: the standard,

3. Measurement

day month yearSolution temperature

MEAS

key to cycle through these display panels.

MEAS

calendar, and clock display panels. Use

Standard panel Calendar panel Clock panel

pH value (or mV)

MEAS MEAS

3.4 Saving a Measured Value

There are two ways to save a measured value: holding temporarily and storing as a record in nonvolatile memory. Measured values stored in nonvolatile memory are not deleted even by replacing the batteries.

(1) HOLD

temporarily and the displayed value no longer changes. Press return to the measurement mode.

key is pressed during measurement, the currently measured value is held

HOLD

hour:minute

MEAS

F030301.EPS

key to

IM 12B03D02-01E

HOLD

MEAS

F030401.EPS

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3. Measurement

(2) Data storage

DATA

If the

F/ENT

key is pressed during measurement, mark starts flashing. Press the

key, then currently measured data can be stored in nonvolatile memory. Data

stored are measured conductivity, measured temperature, date and time. Up to 300 data including individually deleted data can be stored. If you attempt to store more data,

will be displayed.

If is displayed before the data number has reached 300, run defrag referring to Section 5.3 (15), “Defrag memory (DFLG) panel.” This will free up memory occupied

by deleted data, allowing data to be stored newly. To check stored data, refer to Section

5.3 (1), “Display stored data (dAt) panel.”

Pressing

DATA

MEAS

key while mark is flashing cancels data storage and

returns the meter to measurement mode.

Abort data storage.

While is flashing, press or keys to abort data storage.

MEAS

Execute data storage.

Press key to store data while is flashing.

F/ENT

DATA

F030402.EPS

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IM 12B03D02-01E

4. Calibration

Calibration using standard solutions means to measure the pH value of a certified standard solution and to adjust the pH meter so it reads the same value as the certified value of the standard solution. The PH72 meter can be calibrated automatically or manually.

The PH72 meter must be calibrated before measurement if:

• it has been stored for a long period;

• the electrode has been cleaned; or

• otherwise necessary.

Precautions

(1) Use certified standard solutions. Using deteriorated standard solutions will result

in inaccurate calibration. Standard solutions are available as spare parts (see Section 1.8).

Pour a portion of the standard solution into a calibration bottle (supplied) and use for calibration. Do not reuse the portion. Discard it and use a fresh portion for another calibration.

4. Calibration

(2) Do not press

results may be changed.

key unless calibration is needed. Otherwise, saved calibration

CAL

Before Calibration

The following should be checked and set before calibration.

(1) Contamination of the sensor

Make sure that no dirt or deposits are present on the sensor.

(2) Temperatur e setting

When using a sensor without a built-in temperature element, i.e., a needle type or test tube size pH sensor, the temperature of a standard solution to be used should be set into the meter. (Refer to Section 5.3 (2), “Manual temperature setting (M.tP) panel.”)

(3) Battery condition

Check the battery condition indicator for remaining life. If the indicator is flashing, calibration cannot be performed. Replace the batteries. (Refer to Section 2.1, “Installing the Batteries.”)

IM 12B03D02-01E

4-1

4. Calibration

Error Messages during Calibration

If the meter detects an abnormality during calibration, , , or

may be displayed. In such a case take corrective actions referring to Chapter 7,

“Troubleshooting.”

Canceling Calibration

To cancel the calibration procedure, press measurement mode.

CAL

MEAS

key. The meter will return to

1-point and 2-point Calibrations

There are two types of calibrations: 1-point calibration using only one standard solution and 2-point calibration using two standard solutions. One-point calibration is a simplified calibration method which can be used only when the anticipated pH values of sample solutions are near the certified pH value of a standard solution used for calibration. Twopoint calibration is generally recommended.

Calibration results are not affected by turning off the power and saved until the next calibration or the initialization of calibration parameters (see Section 5.3 (11)). The last two calibration results are saved in the meter. Therefore, for 1-point calibration, first initialize calibration parameters and then perform a 1-point calibration, or without initializing, perform a 1-point calibration twice using the same standard solution.

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4.1 Automatic Calibration

In automatic calibration the Model PH72 Personal pH/ORP Meter automatically recognizes standard solutions being used and calibrates itself using values of Table 4.1. Two types of standard solutions are preprogrammed: NIST (solutions prepared in accordance with Japanese standards, factory default) and US (solutions prepared in accordance with the U.S. standards). If NIST is selected, the meter recognizes standard solutions with pH 2, 4, 7, 9, and 12. The meter recognizes standard solutions with pH 4, 7, and 10 if US is selected.

Table 4.1 pH-Temperature Relationship in pH Standard Solutions

d NIST

Temperature 8C

Std. Solution

pH2 pH4 pH7 pH9

pH12

d US

Temperature 8C

Std. Solution

pH4 pH7

pH10

Before Automatic Calibration

0 5 10 15 20 25 30 35 40 4550

4.003

6.984

9.464

13.423

1.668

3.999

6.951

9.395

13.207

1.670

3.998

6.923

9.332

13.003

1.672

3.999

6.900

9.276

12.810

1.675

4.002

6.881

9.225

12.627

1.679

4.008

6.865

9.180

12.454

1.683

4.015

6.856

9.139

12.289

1.688

4.024

6.844

9.102

12.133

1.694

4.035

6.838

9.068

11.984

1.700

4.047

6.834

9.038

11.841

1.707

4.060

6.833

9.011

11.705

1.715

4.075

6.834

8.985

11.574

0 5 10 15 20 25 30 35 40 4550

4.000

7.120

10.317

3.998

7.090

10.245

3.997

7.060

10.179

3.998

7.040

10.118

4.001

7.020

10.062

4.005

7.000

10.012

4.010

6.990

9.966

4.018

6.980

9.926

4.027

6.980

9.889

4.038

6.978

9.856

4.050

6.970

9.828

4.064

6.980

9.828

Make sure that the correct type of standard solutions to be used for automatic calibration has been selected. (Refer to Section 5.3 (10), “Standard solution setting (Std) panel.”)

4. Calibration

55 60 70 80

1.723

1.743

4.126

6.845

8.921

1.766

4.164

6.859

8.885

T0402.EPS

4.091

6.836

8.962

11.449

55 60

4.080

6.980

9.828

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