Yokogawa PH72 User Manual

User’s Manual
Model PH72 Personal pH/ORP Meter
IM 12B03D02-01E
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.
1
Preface
Liquid Crystal Display (LCD) Characters
On the LCD alphanumeric characters are displayed as follows.
Alphabet
A
B
C
D
E
F
G
H
I
J
K
L
M
Display
Alphabet
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Display DisplayNumerals
0
1
2
3
4
5
6
7
8
9
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:
2
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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
IM 12B03D02-01E
3
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
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5
Contents
6
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
1
discharge
RF amplitude
2
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
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*
A
B**
A
A
T0102.EPS
IM 12B03D02-01E

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
IM 12B03D02-01E
1-3
1. Outline

1.4 PH72 Meter Kit

1
7
8 11
3
9
Instrument Card
2
6
Quick Manual
4
10
No.
Item
1
Personal pH/ORP meter
2
Dry batteries, 2x AA batteries
3
User's Manual and Quick Manual
4
Non-slip pads (2 pcs)
5
Hand strap
6
Instrument Card
7
KCl replenish-free type pH sensor
8
KCl refillable type pH sensor
9
Needle type pH sensor
10
Test tube size pH sensor
11
5
KCl refillable type ORP sensor
12
Cotton swabs for sensor cleaning
13
pH 4 standard solution (50 ml)
14
pH 7 standard solution (50 ml)
15
Calibration bottles (2 bottles)
16
KCl filling solution (3.3 mol/l, 50 ml)
17
Syringe (5 ml)
13 14
PH4
PH7
16
KCl
12
15
17
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
IM 12B03D02-01E

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
IM 12B03D02-01E
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
1
: Part number of PH81, PH82 (previous models).
*
2
: 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
1
RemarksModel Suffix Code
*
2
K9220YA
*
K9220YB
2
*
2
*
K9220YC
2
*
K9220YG
2
K9220YJ
*
1
Remarks
*
2
K9220YL
*
2
*
F010601.EPS
1-6
IM 12B03D02-01E
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.
*1
*1
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
*1
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.
*1
Sensor cable
Sensor grip
Prevents filling solution from
leaking from fill hole during storage. Always unplugged during measurement.
1. Outline
F010602.EPS
IM 12B03D02-01E
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
IM 12B03D02-01E

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
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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
to set
F/ENT F/ENT
to confirm
F/ENT
to set
After several seconds
F/ENT
to confirm
to confirm
to confirm
to confirm
or
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
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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. 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
3-1
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
A
Glass electrode tip
Figure 3.3 How to Dislodge Bubbles from Glass Electrode Tip
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IM 12B03D02-01E

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
If
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
HOLD
or
hour:minute
MEAS
F030301.EPS
key to
IM 12B03D02-01E
HOLD
HOLD
or
MEAS
F030401.EPS
3-3
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
or
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
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
or
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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IM 12B03D02-01E

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
-
IM 12B03D02-01E
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