User ’s
Manual
Model FU20
pH/ORP Sensor
IM 12B07K02-01E
IM 12B07K02-01E
4th Edition
<INTRODUCTION>
INTRODUCTION
This user’s manual provides information for the installation and use of the FU20 pH/ORP sensor.
The FU20 is the choice for the majority of typical waste water and process applications.
Upon delivery, unpack the sensor carefully and inspect it to ensure it was not damaged during
shipment. If damage is found, retain the original packing materials (including outer box) and then
immediately notify the carrier and the relevant Yokogawa sales oce. Make sure the Model Code
on the sensor is the same as on the packing list. For details of the Model Code, refer to Sec. 1.2.
Other related items are described in the following manuals.
Model Title IM No.
FLXA202, FLXA21 2-Wire Liquid Analyzer IM 12A01A02-01E
FLXA402 4-Wire Converter IM 12A01F01-02EN
IM 12A01F02-01EN etc.
PH450G 4-wire pH/ORP Converter IM 12B07C05-01E
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Media No. IM 12B07K02-01E 4th Edition : Nov. 2018 (YK)
All Rights Reserved Copyright © 2000, Yokogawa Electric Corporation
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
<INTRODUCTION>
For the safe use of this equipment
n Safety,Protection,andModicationoftheProduct
• In order to protect the system controlled by the product and the product itself and ensure
safe operation, observe the safety precautions described in this user’s manual. We assume
no liability for safety if users fail to observe these instructions when operating the product.
• If this instrument is used in a manner not specied in this user’s manual, the protection
provided by this instrument may be impaired.
• Be sure to use the spare parts approved by Yokogawa Electric Corporation (hereafter
simply referred to as YOKOGAWA) when replacing parts or consumables.
• Modication of the product is strictly prohibited.
n Notes on Handling User’s Manuals
• Please hand over the user’s manuals to your end users so that they can keep the user’s
manuals on hand for convenient reference.
• Please read the information thoroughly before using the product.
• The purpose of these user’s manuals is not to warrant that the product is well suited to any
particular purpose but rather to describe the functional details of the product.
• No part of the user’s manuals may be transferred or reproduced without prior written
consent from YOKOGAWA.
• YOKOGAWA reserves the right to make improvements in the user’s manuals and product at
any time, without notice or obligation.
• If you have any questions, or you nd mistakes or omissions in the user’s manuals, please
contact our sales representative or your local distributor.
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n Warning and Disclaimer
The product is provided on an “as is” basis. YOKOGAWA shall have neither liability nor
responsibility to any person or entity with respect to any direct or indirect loss or damage arising
from using the product or any defect of the product that YOKOGAWA can not predict in advance.
n Signal Words
The following words are used in this manual.
CAUTION
This symbol gives information essential for understanding the operations and functions.
NOTE
This symbol indicates information that complements the present topic.
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
<INTRODUCTION>
After-sales Warranty
n Do not modify the product.
n During the warranty period, for repair under warranty consult the local sales representative
or service oce. Yokogawa will replace or repair any damaged parts. Before consulting for
repair under warranty, provide us with the model name and serial number and a description
of the problem. Any diagrams or data explaining the problem would also be appreciated.
• If we replace the product with a new one, we won’t provide you with a repair report.
• Yokogawa warrants the product for the period stated in the pre-purchase quotation
Yokogawa shall conduct dened warranty service based on its standard. When the
customer site is located outside of the service area, a fee for dispatching the maintenance
engineer will be charged to the customer.
• Returned goods that have been in contact with process uids must be decontaminated
and disinfected prior to shipment. Goods should carry a certicate to this eect, for the
health and safety of our employees. Material Safety Data sheets must be included for all
components of the process to which the sensor have been exposed.
n In the following cases, customer will be charged repair fee regardless of warranty period.
iii
• Failure of components which are out of scope of warranty stated in instruction manual.
• Failure caused by usage of software, hardware or auxiliary equipment, which Yokogawa
Electric did not supply.
• Failure due to improper or insucient maintenance by user.
• Failure due to modication, misuse or outside-of-specications operation which Yokogawa
does not authorize.
• Failure due to power supply (voltage, frequency) being outside specications or abnormal.
• Failure caused by any usage out of scope of recommended usage.
• Any damage from re, earthquake, storms and oods, lightning, disturbances, riots, warfare,
radiation and other natural changes.
n Yokogawa does not warrant conformance with the specic application at the user site.
Yokogawa will not bear direct/indirect responsibility for damage due to a specic application.
n Yokogawa Electric will not bear responsibility when the user congures the product into
systems or resells the product.
n Maintenance service and supplying repair parts will be covered for ve years after the
production ends. For repair for this product, please contact the nearest sales oce
described in this instruction manual.
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
Blank Page
<CONTENTS>
Model FU20
pH/ORP Sensor
IM 12B07K02-01E 4th Edition
CONTENTS
INTRODUCTION .............................................................................................i
For the safe use of this equipment .............................................................ii
After-sales Warranty ...................................................................................iii
1. Specication ............................................................................................. 1-1
1.1 StandardSpecications ................................................................................... 1-1
1.2 ModelandSuxcodes .................................................................................... 1-1
1.3 ExternalDimensions ........................................................................................1-2
2. Installation and Wiring ............................................................................. 2-1
2.1 Installation ......................................................................................................... 2-1
2.2 Wiring ................................................................................................................. 2-1
v
3. Maintenance .............................................................................................. 3-1
Revision Information ...............................................................................................i
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
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<1.Specication>
1. Specication
The Model FU20 oers a simple and cost eective solution for a wide variety of waste water and
process applications. This all-in-one sensor provides simultaneous measurement of pH, ORP
and temperature. The rugged Ryton body is designed for easy installation into on-line via the 3/4
inch tapered threaded connections provided on both ends of the sensor.
1.1 StandardSpecications
Measuring range: pH; 2 to 12 ORP; -1500 to 1500 mV
Solution temperature : -5 to 105°C (sensor only, sample is not freezed)
Solution pressure : 0 to 1 MPa (sensor only)
Solution conductivity : 50 µS/cm or higher
Solution ow velocity : 2 m/s max.
Internal electrolyte: Saturated KCl (Non rellable)
Temperature sensor : Pt1000 (Note)
Body materials: Ryton (PPS 40GF)
Weight: Approx. 0.5 kg (Body)
Storage temperature: -10 to 50 °C
Applicable Liquid Analyzer/converter: FLXA202/FLXA21 2-Wire Liquid Analyze,
FLXA402 4-Wire Converter, PH450G pH/ORP converter
Applicable holder: Special order for PH8HG, HH350G with optional adapter, cannot be
used with HH350G/-JT.
Note: The temperature sensor included in the FU20 is intended to provide indication and cell compensation. The construction has not
been tested to the pressure vessel standards required for plant temperature control.
1-1
NOTE
Cautions for using the FU20 sensor
Note that the FU20 sensor has limited life which depending on installation process.
Be careful not to allow liquid junction and glass of the pH sensor to dry out.
When storing the sensor, be sure to attach the protective cap (supplied with it on shipment) to its tip.
The sensing glass membrane of the pH sensor gradually deteriorates during storage.
A virgin pH sensor may become unusable because of its deterioration. Avoid storing the sensor
for a long time (Use within a year is recommended).
1.2 ModelandSuxcodes
Model SuxCode
FU20 ................................... ................... Wide body Sensor
Type -05
-10
Temperature element -T1 ................... Pt1000
Model -NPT ................... Dome shape model
Note: Special order is needed for using with PH8HG drop-in guide pipe.
Option Code
...................
...................
Fixed cable 5 meter
Fixed cable 10 meter
Description
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
<1.Specication>
1.3 ExternalDimensions
Standard type (FU20--T1-NPT)
16
15
13 14
11 12
1-2
Unit: mm
3/4 inch
tapered thread
(Note)
Sensor body
(PPS resin)
3/4 inch
tapered thread
(Note)
PG7
Ø25.9
Ø6.5
Cable length (5 m or 10 m)
19.6
150
19.6
22.5
(Note) Can be fixed to 3/4NPT female screw.
Figure 1.1 FU20 pH/ORP Sensor
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
< 2. Installation and Wiring >
2. Installation and Wiring
2.1 Installation
For optimum measurement results, the FU20 should be installed in a location that oers an
acceptable representation of the process composition and DOES NOT exceed the specications
of the sensor.
This sensor should be installed rain-proof or drip-proof area where rainwater cannot get inside
through the cable inlet/outlet, because insulation of sensor will be decreased due to exposure to
rain or due to condensation at a high humid place.
Take care that screw-in force is not too large.
Special orderis needed for using with PH8HG drop-in guide pipe.
n In-line Installation
The FU20 sensor is designed for in-line installation, via a bypass loop as an immersion assembly.
For best results the FU20 should be mounted with the process coming towards the sensor and
positioned at least 15° above the horizontal plane to eliminate air bubbles in the glass bulb.
The FU20 can be mounted using the threads on the sensor body (Figure 2.1).
Apply Teon tape to the appropriate threaded end, then install in the process.
How to apply Teon tape: Apply seven turns or more Teon tape from the thread end in piles
(thickness of tape: approximately 0.1 mm, width of tape: approximately 13 mm).
Apply more turns of Teon tape for leakage.
Screw-in torque of sensor is approximately 4 N∙m.
2-1
PG7
Teflon tape
Figure 2.1 In-line Installation
2.2 Wiring
Mark band of sensor is shown by numeral and pin terminals are used, connect each core wire to
the corresponding terminals of transmitter or converter. For details of wiring, refer to relevant IMs
of transmitter or converter.
PG7
FU20
FU20
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
< 2. Installation and Wiring >
For pH and ORP measurement
Wire Marking
11
12
13
14
15
16
PG7
Figure 2.2 Sensor Wiring for pH and ORP measurement
FLXA202/FLXA21/FLXA402/PH450G
(11)
TEMPERATURE
(12)
TEMPERATURE
(13)
REFERENCE
(14)
SOLUTION GROUND
(15)
GLASS (Measure)
(16)
GE SHIELD
(17)
For pH measurement
Wire Marking
PG7
FLXA202/FLXA21/FLXA402/PH450G
(11)
11
12
13
14
15
16
TEMPERATURE
(12)
TEMPERATURE
(13)
REFERENCE
(14)
SOLUTION GROUND
(15)
GLASS (Measure)
(16)
GE SHIELD
(17)
2-2
Figure 2.3 Sensor Wiring for pH measurement
For ORP measurement
Wire Marking
11
12
13
14
15
16
PG7
*1: Wires of 11, 12, 15 and 16 are not used, wrap these wires with an insulating
tape or related protection.
*2: For ORP measurement not all numbers are correct, look at the wiring diagram
and short terminals (13) and (14) of converter.
Figure 2.4 Sensor Wiring for ORP measurement
FLXA202/FLXA21/FLXA402/PH450G
(11)
(*1)
(12)
(*1)
(*1)
(*1)
(13)
REFERENCE
(14)
SOLUTION GROUND
(15)
ORP (Measure)
(16)
SHIELD
(17)
(*2)
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
< 3. Maintenance >
3. Maintenance
The sensor has limited life. If buer solution calibration becomes impossible due to deterioration
of the sensor, replace it with a new one. After the sensor is replaced, always carry out a buer
solution calibration.
NOTE
A glass electrode whose glass membrane has dried out does not provide stable readings until
it gets used to the solution. Place in advance the glass electrode in the 3 mol/L KCl solution for
several hours. When storing the sensor, use a sensor cap (supplied with it on shipment) to its tip.
n Cleaning Electrode and Liquid Junction
Staining of an electrode or liquid junction can cause measurement errors. Therefore, if he
measured solutions tend to stain the electrode, the electrode and liquid junction must be cleaned
periodically - depending on the degree of staining.
To clean the sensor, proceed as follows:
(1) Take out the sensor.
3-1
(2) Clean the electrode or liquid junction as follows. Dierent cleaning solutions may be
required depending on the staining.
● Stains due to suspended Solids, Sticky Materials, Microbes or the like
Using soft tissue paper, wipe the stains o the electrode or liquid junction. In addition, clean
o remaining stains by rinsing with water.
● Stains due to Oily Materials
Wash o stains by submerging in a neutral detergent solution in a beaker, etc, (for from
several tens of minutes to several hours depending on the degree of staining).
● Chemical Stains such as due to Metallic Adsorption
Place the electrode or liquid junction in a diluted hydrochloric acid solution (1 to 2%) for
several minutes (acid washing). Afterwards rinse the sensor with water.
● Protein Deposits
It should be removed with a protein enzymatic solution. For instance a solution containing
8.5 mL concentrated hydrochloric acid and 10 gram pepsin in 1 liter water will do.
(3) Check deterioration of the sensor.
(4) Calibrate the sensor with buer solution.
(5) Mount the sensor again.
CAUTION
Avoid using non-polar solvent like tri-chloro ethylene, toluene or hexane. Cleaning with iso-
propanol or methanol is acceptable.
The non-polar solvents will break up the gel-layer on the glass bulb and requires that the
electrode to be soaked in water for at least 12 hours before functioning normally again.
The Teon (PTFE) diaphragm of the sensor can sometimes be regenerated by putting it in hot
(approx. 70°C) 3 molar Potassium Chlorine (KCl) solution and letting it cool to room temperature.
For details of calibration procedure, refer to relevant user’s manual of transmitter/converter.
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
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Revision Information
Title : Model FU20 pH/ORP Sensor
Manual No. : IM 12B07K02-01E
Nov. 2018/4th Edition
Added FLXA402
Pi, P1-1, P2-2
Oct. 2015/3rd Edition
Added FLXA202, Deleted PH400G/OR400G
Pi, P1-1, P2-2
Supplement of 2nd Edition;
Page 1-2, Some revision of FU20 external dimensions.
Page 2-1, Some revision of Sec. 2.1.1 (how to apply Teon tape to the thread end of sensor body).
Mar. 2013/2nd Edition Allover revised by InDesign format
P ii to iv, “For the safe use of this equipment” and “After-sales Warranty” added;
P 1-1, Some revision of standard specications, option code of "/NAG" deleted for "Model- and sux
codes FU20";
P 1-2, Some revision of external dimensions;
P 2-1, Some revision of "Installation", and "In-line Installation" added (screw-in torque changed);
P 2-2, Some revision of "Wiring" with combined transmitter/converter,
(conduct wiring according only to the marking numbers attached onto the core wires as
referring to the corresponding gure, and disregard the color codes of the core wires.) ;
P 3-1, Some revision of "Maintenance" procedure and caution of cleaing sensor added;
Last page, Addition of "Revision Information".
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Nov. 2000/1st Edition
Newly published.
If you want to have more information about Yokogawa products, you can visit
n
Yokogawa’s home page at the following web site.
Home page: http://www.yokogawa.com/an
IM 12B07K02-01E
4th Edition : Nov.20,2018-00
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