YSI Pro20i Operating Manual

Pro20

User Manual

DOCUMENT #605597

Pro20i

USER MANUAL

English

Item #605597
Rev C, September 2016
For the latest version of this manual,
visit ysi.com

©2016 YSI Incorporated.

The YSI logo is a registered trademarks of YSI Incorporated.

CONTENTS

Warranty ................................................................................................i

Introduction

Getting Started ....................................................................................1

System Setup Menu ............................................................................9

.........................................................................................1

Initial Inspection

Battery Installation

Key Pad ....................................................................................2

Connecting the Sensor and Cable

Membrane Installation ...........................................................5

Run Screen

Backlight

Powering Off

Navigation ..............................................................................7

First Power On

DO Local% ..............................................................................9

Last Digit Suppression (LDS)

One Touch Calibration (One Touch Cal)

Audio ...................................................................................11

.................................................................................7

.....................................................................1

.................................................................1

......................................3

..............................................................................6

...........................................................................7

........................................................................8

..............................................10

............................11

Contrast

Sensor Type ..........................................................................12

Membrane Type

Auto Stable ...........................................................................13

DO Units................................................................................14

Temperature Units

Pressure Units

Language

Auto Shutoff ..........................................................................15

Resetting the System Setup Menu to Factory Default

Exiting The System Setup Menu

.................................................................................11

...................................................................12

................................................................14

.......................................................................15

..............................................................................15

......15

.........................................16

Calibration .........................................................................................17

Temperature .........................................................................17

Barometer .............................................................................17

Dissolved Oxygen ................................................................17

Salinity Compensation Calibration .....................................21

Taking Measurements .......................................................................22

Saving and Viewing Data ..................................................................23

Saving Data ...........................................................................23

Viewing and Erasing Saved Data – Data Mode .................23

Principles of Operation ....................................................................25

Care, Maintenance and Storage ......................................................26

General Maintenance ..........................................................26

Sensor Maintenance ............................................................28

Sensor Storage .....................................................................32

Troubleshooting ................................................................................33

Specifications .....................................................................................35

Accessories / Part Numbers .............................................................35

Declaration of Conformity ................................................................37

Recycling ............................................................................................38

Battery Disposal ...................................................................38

Contact Information ..........................................................................39

Ordering and Technical Support ........................................39

Service Information ..............................................................39

WARRANTY

The YSI Pro20/Pro20i instrument is warranted for three (3) years from date
of purchase by the end user against defects in materials and workmanship,
exclusive of batteries and any damage caused by defective batteries.
Pro20/Pro20i cables are warranted for two (2) years from date of purchase
by the end user against defects in material and workmanship.

Pro20/Pro20i Polarographic sensors are warranted for one (1) year and
Galvanic sensors are warranted for six (6) months from date of purchase by
the end user against defects in material and workmanship.

Pro20/Pro20i instruments, cables & probes are warranted for 90 days
from date of purchase by the end user against defects in material and
workmanship when purchased by rental agencies for rental purposes.

Within the warranty period, YSI will repair or replace, at its sole discretion,
free of charge, any product that YSI determines to be covered by this
warranty.

To exercise this warranty, call your local YSI representative, or contact
YSI Customer Service in Yellow Springs, Ohio at [phone], 800­897-4151 or visit www.ysi.com (Support tab). Send the product and proof
of purchase, transportation prepaid, to the Authorized Service Center
selected by YSI. Repair or replacement will be made and the product
returned, transportation prepaid. Repaired or replaced products are
warranted for the balance of the original warranty period, or at least 90
days from date of repair or replacement.

LIMITATION OF WARRANTY

This Warranty does not apply to any YSI product damage or failure caused
by:

1. Failure to install, operate or use the product in accordance with YSI’s
written instructions;

2. Abuse or misuse of the product;

3. Failure to maintain the product in accordance with YSI’s written
instructions or standard industr y procedure;

4. Any improper repairs to the product;

5. Use by you of defective or improper components or parts in servicing
or repairing the product;

6. Modification of the product in any way not expressly authorized by YSI.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR
IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE. YSI’S LIABILITY UNDER THIS WARRANTY
IS LIMITED TO REPAIR OR REPLACEMENT OF THE PRODUCT, AND THIS
SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY DEFECTIVE

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PRODUCT COVERED BY THIS WARRANTY. IN NO EVENT SHALL YSI BE
LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL
DAMAGES RESULTING FROM ANY DEFECTIVE PRODUCT COVERED BY
THIS WARRANTY.

ii

INTRODUCTION

Thank you for purchasing the YSI Pro20/Pro20i, an instrument from the
YSI Professional Series product family. The Pro20 features user-replaceable
cables, while the Pro20i features an integral (i.e. built-in) cable. Sensors
are user-replaceable on Pro20 and Pro20i cables.

The Pro20/Pro20i features an impact resistant and waterproof (IP-

67) case, backlit display, user-selectable sensor options, internal

barometer, and a rugged, rubber over-mold case.

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The Pro20/Pro20i provides valuable instructions and prompts near
the bottom of the display that will guide you through operation and
use. However, reading the entire manual is recommended for a better
understanding of the Pro20/Pro20i’s features.

The Pro20/Pro20i can not communicate to a PC via a Pro Plus
communications saddle. Connecting the Pro20/Pro20i to a
communication saddle may cause erratic instrument behavior.

GETTING STARTED

INITIAL INSPECTION

Carefully unpack the instrument and accessories and inspect for
damage. Compare received parts with items on the packing list. If
any parts or materials are damaged or missing, contact YSI Customer
Service at 800-897-4151 ([phone]) or the authorized YSI
distributor from whom the instrument was purchased.

BATTERY INSTALLATION

The instrument requires 2 alkaline C-cell batteries. Under normal
conditions, the average battery life is 400 hours at room temperature

without using the back light. A battery symbol will blink in
the lower, left corner of the display to indicate low batteries when
approximately 1 hour of battery life remains.

To install or replace the batteries:

1. Turn the instrument off and flip over to view the battery cover

on the back.

2. Unscrew the four captive battery cover screws.

1

3. Remove the battery cover and remove the old batteries if
necessary.

4. Install the new batteries, ensuring correct polarity alignment
(figure 1).

5. Place the battery cover on the back of the instrument and
tighten the four screws. Do not over-tighten.

Figure 1. Pro20/Pro20i with battery cover removed.

Notice battery symbols indicating polarities.

The waterproof instrument case is sealed at the factory and

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is not to be opened, except by factory-authorized service
technicians. Do not attempt to separate the two halves of the
instrument case as this may damage the instrument, break the
waterproof seal, and will void the warranty.

KEY PAD

2

3

1

Figure 2, Keypad

2

4

5

6

Number Key Description

1

Calibrate

Press and hold for 3 seconds to calibrate.

Initiates One Touch Calibration. Opens

Calibrate menu from the run screen if

One Touch Calibration is disabled.

2

Up Arrow

Use to navigate through menus, to

navigate through box options along

the bottom of the Run screen, and

to increase numerical inputs.

3

Power and Backlight

Press once to turn instrument on. Press a
second time to turn backlight on. Press a
third time to turn backlight off. Press and

hold for 3 seconds to turn instrument off.

4

Menu

Use to enter the System Setup

menu from the run screen.

5

Enter

Press to confirm entries and selections.

6

Down Arrow

Use to navigate through menus, to

navigate through box options at

the bottom of the Run screen and

to decrease numerical inputs.

CONNECTING THE SENSOR AND CABLE

CONNECTING THE SENSOR

“Sensor” refers to the removable portion or electrode sensing portion
of the cable assembly, i.e. the dissolved oxygen sensor. “Bulkhead”
refers to the portion of the cable with the single-pin connector (Figure

3).

3

The Pro20/Pro20i has two compatible sensors for use with a field cable:

Polarographic – This sensor has a black sensor body and is engraved
with the model number 2003. Polarographic will be abbreviated Polaro
in the instrument’s menu.

Galvanic – This sensor has a grey sensor body and is engraved with the
model number 2002.

For information about the differences on the two sensor types, see
Sensor Type in the System Setup menu section and/or the Principles of
Operation section of this manual.

If using a ProBOD sensor/cable assembly, there is no need to install a
sensor because it has a built in Polarographic dissolved oxygen sensor.

Before installing either sensor or connecting the cable (Pro20
only) to the instrument, the Sensor Type must be configured
for the sensor being installed/connected. Failure to do this
may result in damage not covered under warranty. The

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instrument will step you through this setup the first time it
is powered on. See the System Setup menu section of this
manual for instructions on configuring the Sensor Type after
the first power on.

1. Ensure both the sensor connector and sensor port on the cable are
clean and dry.

2. Grasp the sensor with one hand and the cable bulkhead in the
other.

3. Push the sensor into the connector on the cable until it is firmly
seated and only 1 o-ring is visible. Failure to properly seat the
sensor may result in damage.

4. Twist the sensor clockwise to engage threads and finger tighten.
Do NOT use a tool. This connection is water-tight.

For more detailed instructions, please refer to the sensor installation
sheet that is included with each sensor.

Figure 3

4

Connecting the Cable (Pro20 Only)

The Pro20 is designed for field and laboratory use. It is compatible with
two different cable options:

1. The field rugged cable is available in standard lengths of 1, 4, 10,

20, 30, and 100 meters with special lengths available between 30
and 100 meters. This cable has a built in temperature sensor and
includes a port for the dissolved oxygen sensor.

2. The ProBOD is a 1 meter probe/cable assembly with built in

Polarographic dissolved oxygen and temperature sensors. It has
an AC powered motor for sample stirring and is designed to fit into
a 300 ml BOD bottle.

To connect the cable, align the keys on the cable connector to the slots
on the instrument connector. Push together firmly and then twist the
outer ring until it locks into place (figure 4). This connection is water­proof.

Figure 4, Note the keyed connector.

When disconnected, the sensor and cable’s sensor connectors
are NOT water-proof. Do not submerge the cable without a
sensor installed. When disconnected, the cable’s instrument
connector and the connector on the instrument maintain a

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waterproof, IP-67 rating.

MEMBRANE INSTALLATION

The dissolved oxygen sensor is shipped with a dry, protective red cap
that will need to be removed before using. It is very important to put a
new membrane with electrolyte solution on the sensor after removing
the red cap.

5

Prepare the membrane solution according to the instructions on the
bottle. After mixing, allow the solution to sit for 1 hour. This will help
prevent air bubbles from later developing under the membrane.
Ensure you are using the correct electrolyte solution for the correct
sensor. Galvanic sensors utilize electrolyte with a light blue label
and Polarographic sensors utilize electrolyte with a white label. The
Dissolved Oxygen sensor is supplied with cap membranes specific
to the sensor type ordered (Polarographic or Galvanic). 5913 and
5914 membrane kits are for Galvanic sensors and the 5908 and 5909
membrane kits are for Polarographic sensors.

Remove and discard or save the red protective cap. Thoroughly rinse
the sensor tip with distilled or deionized water. Fill the cap membrane
3⁄4 full of electrolyte solution, then tap the cap with a finger to release
any trapped air. Be careful not to touch the membrane portion of the
cap. Thread the membrane cap onto the sensor, moderately tight.
Do not use a tool. It’s typical for some of the electrolyte solution to
spill over. It is best to allow the new cap to remain on a new sensor
overnight before trying to calibrate. For detailed instructions on
changing a membrane cap, see the Care, Maintenance, and Storage
section of this manual.

RUN SCREEN

Press the power/backlight key to turn the instrument on. The
instrument will run through a self test and briefly display a splash screen
with system information before displaying the main Run screen (figure

5). The first time the Pro20/Pro20i is turned on, it will step through

language, sensor, and membrane selections; see the First Power On
section of this manual for more information.

Figure 5, Run screen.

6

BACKLIGHT

Once the instrument is powered on, pressing the power/backlight key

will turn on the display backlight. The backlight will remain on until
the key is pressed again or after two minutes of not pressing any key
on the keypad.

POWERING OFF

To turn the instrument off, press and hold the power/backlight key
for three seconds.

NAVIGATION

The up and down arrow keys allow you to navigate through the
functions of the Pro20/Pro20i.

Navigating the Run Screen

When in the Run screen, the up and down arrow keys will move the
highlighted box along the bottom options. Once a box is highlighted,

press enter

Description of Run screen box functions from left to right:

to access the highlighted option.

Option Description

Barometer Highlight and press enter to calibrate the

instrument’s internal barometer.

Salinity

compensation

value

SAVE

DATA

Highlight and press enter to adjust the salinity
compensation value that is used for the
dissolved oxygen mg/L measurement.

Highlight and press enter to save displayed
data to memory.

Highlight and press enter to view and/or erase
saved data.

7

Navigating the System Setup Menu

Select Sensor Type:



Polaro (black)



Galvanic (grey)

Use  to select
sensor type
Press  to confirm

Select Membrane
Type:

1.25 (Yellow)
 2.0 (Blue)

Use  to select
membrane
Press  to confirm

When in the System Setup menu, the up and down arrow keys will
move the highlighted bar up and down the system setup options. See
the System Setup menu section of this manual for more information
about these options.

FIRST POWER ON

The instrument will step through an initial configuration when powered
on for the first time. This will set the language, sensor, and membrane
options. Use the up or down arrow keys to highlight the appropriate
language, sensor, and membrane, then press enter to confirm (Figures
6, 7, and 8). The Sensor Type must be configured for the sensor
installed. Failure to do this may result in damage not covered under
warranty. If an incorrect option is selected, it may be changed in the
System Setup menu.

Figure 7, Sensor selection Figure 8, Membrane selection

Figure 6, Language selection

8

After selecting a language, sensor, and membrane, the run screen will
appear. The next time the instrument is powered up the run screen
will appear immediately after the self check. If the sensor type or
membrane type is changed, ensure that it updated in the System Setup
menu.

SYSTEM SETUP MENU

Press the menu key to access the System Setup menu. The System
Setup menu contains three screens notated as ‘pages’. The current
page is indicated near the bottom of the display (figure 9).

DO LOCAL%

DO Local% can be enabled or disabled by using the up or down arrow

keys to highlight it and then pressing enter
DO Local% indicates it is enabled (Figure 9).

. An ‘X’ in the box next to

Figure 9, DO Local% is enabled.

When DO Local% is enabled, DO% values will be expressed as %L on
the Run screen.

DO Local% allows for localized % saturation measurements, but does
not affect the mg/L readings. When enabled, the DO%L calibration
value is always 100% regardless of the altitude or barometric
pressure of the location. This deviates from YSI’s traditional method of
expressing DO% saturation where the % calibration value decreases
with a decrease in barometric pressure, i.e. an increase in altitude (See
appendix A). To determine the % calibration value when DO Local% is
disabled, divide the local, true barometric pressure in mmHg by 760
and then multiply by 100.

9

Example: 750/760 = 0.9868 x 100 = 98.68% calibration value when
DO Local is disabled.

When DO Local% is enabled, the Pro20/Pro20i corrects for barometric
pressure for each DO measurement instead of during calibration.

Example:
Instrument #1 with DO Local% enabled:
At 737 mmHg barometric pressure, roughly 841 ft above sea level, the
instrument would calibrate to 100%.

When taking measurements at the same location (737 mmHg) in a 20°C
fresh water sample that is completely air-saturated, the instrument
would read:

DO %L value = 100%
DO mg/L value = 8.81 mg/L (9.09

1

x .96972)

Instrument #2 DO Local% disabled:
At 737 mmHg barometric pressure, roughly 841 ft above sea level, the
instrument would calibrate to 737/760 x 100% = 96.97%

When taking measurements at the same location (737 mmHg) in a 20°C
fresh water sample that is completely air-saturated, the instrument
would read:

DO% value = 96.97%
DO mg/L value = 8.81 mg/L (9.091 x .96972)

Hence, the mg/L readings are unaffected by DO Local%.

1.) Value from oxygen solubility table (Appendix B).

2.) 737/760 x 100%, correction for barometric pressure.

LAST DIGIT SUPPRESSION (LDS)

Last Digit Suppression (LDS) can be enabled or disabled by using the

up or down arrow keys to highlight it and pressing enter
the box next to LDS indicates it is enabled.

. An ‘X’ in

LDS rounds the DO value to the nearest tenth; i.e. 8.25 mg/L becomes

8.3 mg/L. LDS is automatically disabled during calibrations.

10

ONE TOUCH CALIBRATION (ONE TOUCH CAL)

One Touch Calibration can be enabled or disabled by using the up or

down arrow keys to highlight One Touch Cal and pressing enter
An ‘X’ in the box next to One Touch indicates it is enabled.

.

When One Touch Cal is enabled, press and hold the calibration
for 3 seconds while in the run screen to calibrate Dissolved Oxygen
to the barometer reading and salinity correction value. For more
information on One Touch Calibration, see the Calibration section of
this manual.

key

AUDIO

Audio can be enabled or disabled by using the up or down arrow keys

to highlight Audio and pressing enter. When enabled, there will be an
‘X’ in the box next to Audio.

When Audio is enabled, the Pro20/Pro20i will beep twice to indicate
stability when Auto Stable is enabled. The instrument will also beep
when a key is pressed. When Audio is disabled, the Pro20/Pro20i will
not beep.

CONTRAST

To adjust the display Contrast, use the up or down arrow keys to
highlight Contrast, then press enter. Next, use the up or down arrow
keys to adjust the contrast. The up arrow key will darken the contrast
and the down arrow key will lighten the contrast. After adjusting the
contrast, press enter to save and exit the Contrast adjustment function.

Alternate Contrast Adjustment Option

If necessary, there is an alternate method of adjusting the contrast. To
adjust the contrast, press and hold the menu key, then press the up
arrow key to darken the contrast or press the down arrow key to lighten
the contrast.

11

SENSOR TYPE

The instrument’s Sensor Type must be configured for the

sensor installed. Failure to do this may result in damage not

covered under warranty. If you observe readings very close

i

to 0 or extremely high readings, e.g. 600%, your Sensor Type

setting may be set incorrectly.

Sensor Type sets the type of dissolved oxygen sensor being used;
either polarographic (black) or galvanic (grey).

Use the up or down arrow keys to highlight Sensor Type, then press
enter

to the sensor installed on the cable and press enter to confirm. The
enabled sensor type will have an ‘X’ in the box next to it. Next, use the
down arrow key to highlight the ESC – Exit box, then press enter to
save changes and to close the sensor submenu.

If using a ProBOD sensor/cable assembly, the sensor type should be
set to polarographic.

The Pro20/Pro20i has two compatible sensors for use with a field cable:

• Polarographic – This sensor has a black sensor body and is

• Galvanic – This sensor has a grey sensor body and is engraved

to open a submenu. Highlight the sensor type corresponding

engraved with the model number 2003. Polarographic will be
abbreviated Polaro in the instrument menu.

with the model number 2002.

In terms of physical configuration, membrane material and general
performance, YSI Pro Series galvanic sensors are exactly like the Pro
Series polarographic sensors. The advantage of using galvanic sensors
is convenience. Galvanic sensors provide an instant-on sensor without
the need for warm-up time but this affects the life of the sensor.
Polarographic sensors last longer and have a longer warranty but
require a 5-15 minute warm-up time before use or calibration.

MEMBRANE TYPE

Membrane Type sets the type of membrane used on the dissolved

oxygen sensor; either 1.25 PE (Yellow) or 2.0 PE (blue). Use the up
or down arrow keys to highlight Membrane Type and press enter to
open the submenu. Highlight the membrane type corresponding to
the membrane installed on the sensor and press enter to confirm. The

12

enabled membrane type will have an ‘X’ in the box next to it. Use the
down arrow key to highlight the ESC – Exit box and press enter to save
changes and to close the membrane submenu.

The dissolved oxygen sensor is supplied with membranes specific
to the sensor type and are color coded as described in the following
tables.

Galvanic Membrane Kits:

Model Color Material Description

5913 Yellow 1.25 mil

polyethylene (PE)

5914 Blue 2.0 mil

polyethylene (PE)

Faster response time and less flow
dependence than traditional FEP
membranes.

Less flow dependence than 1.25 mil
membrane but little slower response.

Polarographic Membrane Kits:

Item Color Material Description

5908 Yellow 1.25 mil

polyethylene (PE)

5909 Blue 2.0 mil

polyethylene (PE)

Faster response time and less flow
dependence than traditional FEP
membranes.

Less flow dependence than 1.25 mil
membrane but a little slower response.

Selecting a Dissolved Oxygen Membrane:

Membrane

Type

5913, 5908

Yellow

5914,
5909 Blue

Flow Dependence

After 4 Minutes

25% 6 inches/second 8 seconds

18% 3 inches/second 17 seconds

Required Sample

Movement

Typical Response

Time (T-95)

AUTO STABLE

Auto Stable utilizes preset values to indicate when a reading is stable.

The preset values are adjustable in the System Setup menu. The user
can input a % change in dissolved oxygen readings (0.0 to 1.9) over ‘x’
amount of time in seconds (3-19).

Highlight Auto Stable and press enter
Use the up or down arrow keys to highlight the DO% Change or
seconds (secs) input field, then press enter to make the highlighted
field adjustable. Use the up and down arrow keys to adjust the selected
value, then press enter to confirm changes. Once you have confirmed

13

to expand the submenu.

any changes, highlight the ESC-Exit box and press enter to close the

AS

AS

Auto Stable submenu.

To disable Auto Stable, set the DO% Change input to 0.0.

When Auto Stable is enabled, an

symbol will display next to the
dissolved oxygen value on the run screen and blink during stabilization.
When the dissolved oxygen value has stabilized based on the Auto

Stable settings, the

will display steadily and the instrument will

beep twice if Audio is turned on.

DO UNITS

Highlight DO Units and press enter to open a submenu that allows
you to select the dissolved oxygen units to be displayed on the Run
screen. Highlight the desired unit(s) and press enter to enable or
disable. An enabled dissolved oxygen unit will have an ‘X’ in the box
next to it. Highlight the ESC-Exit box and press enter to save any
changes and to close the DO units submenu.

There are three options for displaying dissolved oxygen:

• mg/L will show DO readings in milligrams per liter on a scale

from 0 to 50 mg/L.

• ppm (parts per million) is equivalent to mg/L and will show the

DO reading on a scale from 0 to 50 ppm.

• % will show DO readings in a % saturation from 0 to 500%. This
value will be expressed as %L when DO Local% is enabled.

Both % or %L and mg/L or ppm can be displayed simultaneously on
the screen.

TEMPERATURE UNITS

Highlight Temperature Units and press enter to open a submenu
that allows you to change the temperature units displayed on the Run
screen. Highlight the desired unit (Celsius or Fahrenheit) and press
enter to enable. The enabled temperature unit will have an ‘X’ in the
box next to it. Only one unit may be enabled at a time. Highlight the
ESC-Exit box and press enter to save any changes and to close the
Temperature Units submenu.

14

PRESSURE UNITS

Highlight Pressure Units and press enter to open a submenu that
allows you to change the barometric pressure units displayed on the
Run screen. Highlight the desired unit (mmHg, inHg, mbar, psi, or kPa)
and press enter to enable. The enabled pressure unit will have an ‘X’
in the box next to it. Only one unit may be enabled at a time. Highlight
the ESC-Exit box and press enter to save any changes and to close the
Pressure Units submenu.

LANGUAGE

Highlight Language and press Enter to open a submenu that will allow
you to change the language. Highlight the desired language (English,
Spanish, German, or French) and press enter to enable. The enabled
language will have an ‘X’ in the box next to it. Highlight ESC-Exit
box and press enter to save any changes and to close the Language
submenu.

The text in the boxes along the bottom of the run screen will always be
displayed in English regardless of the language enabled in the System
Setup menu.

AUTO SHUTOFF

Auto Shutoff allows you to set the instrument to turn off automatically

after a period of time after the last button press. In the setup menu, use
the up or down arrow keys to highlight Auto Shutoff, then press enter
to open the submenu. Press enter while the minute field is highlighted
to make it adjustable. Next, use the up or down arrow keys to adjust the
shut off time from 0 to 60 minutes. Press enter to save the new shutoff
time. Next, highlight the ESC-Exit box and press enter to close the
submenu. To disable Auto Shutoff, set the Time in Minutes to 0 (zero).

RESETTING THE SYSTEM SETUP MENU
TO FACTORY DEFAULT

To reset the Pro20/Pro20i settings back to factory default, press the
down arrow key while in the System Setup menu until the Reset -
box is highlighted, then press enter. The instrument will prompt you
to confirm the reset. Highlight Yes and press enter to continue with
the reset or highlight No and press enter to cancel the reset. A Factory
Reset will not affect data saved in the instrument’s memory.

The following will be set in the Pro20/Pro20i after performing a reset:

15

Parameter Reset Defaults

Temperature Units

o

C

Dissolved Oxygen Units mg/L and %

Pressure Units mmHg

Dissolved Oxygen Sensor Type Last Setting Confirmed

Membrane Type Last Setting Confirmed

Salinity Compensation Value 0.0 ppt

DO Local% Off

One Touch Cal On

Display Contrast Set to mid range

Auto Shutoff 30 minutes

Auto Stable Off (0.0 % Change and 10 secs)

LDS (Last Digit Suppression) Off

Audio On

Language English

Dissolved Oxygen Calibration Reset to factory default, 100% for

enabled membrane and sensor*

Barometer Calibration Reset to factory default*

*It is recommended to perform a barometer and dissolved oxygen
calibration after performing a reset.

EXITING THE SYSTEM SETUP MENU

To exit the System Setup menu, press the down arrow key until the
ESC - Exit box is highlighted, then press enter

screen.

16

to return to the run

CALIBRATION

TEMPERATURE

All cable assemblies have built-in, temperature sensors. Temperature
calibration is not required nor is it available.

BAROMETER

The barometer in the Pro20/Pro20i is calibrated at the factory. The
barometer reading must be accurate to ensure accurate % calibrations
and DO readings. If your barometer requires an adjustment, use the up
or down arrow keys to highlight the barometer box on the run screen,

then press enter
barometer reading to the local, true barometric pressure. Continually
depress the up or down arrow keys to change the barometer value more
rapidly. Press enter to confirm and save the barometer adjustment.

Do not use a barometer value that is corrected to sea level.
Laboratory barometer readings are usually “true” (uncorrected)
values of air pressure and can be used “as is” for barometer
calibration. Weather service readings are usually not “true”, i.e.,

i

they are corrected to sea level, and therefore cannot be used
until they are “uncorrected”. An approximate formula for this
“uncorrection” is:

. Next, use the up or down arrow keys to adjust the

True BP = [Corrected BP] – [2.5 * (Local Altitude in ft above sea level/100)]

Although the barometer range is 400.0 to 999.9 mmHg, you will be
unable to adjust the value across the entire range. The barometer is
very accurate and the instrument will not allow you to adjust the value
drastically beyond what it is measuring during calibration.

DISSOLVED OXYGEN

The Pro20/Pro20i can be easily calibrated with the press of one key by
enabling One Touch Cal in the System Setup menu and following the
One Touch Calibration procedure.

Ensure the barometer is reading accurately before performing a One
Touch Calibration, DO %, or DO Local% calibration. These calibration
procedures use the barometer reading during calibration. If the
barometer reading is erroneous during a calibration, your dissolved
oxygen values will be inaccurate.

17

It is not necessary to calibrate in both % and mg/L or ppm.
Calibrating in % will simultaneously calibrate mg/L and ppm
and vice versa. YSI recommends calibrating dissolved oxygen

i

in % for both ease and accuracy.

ONE TOUCH CALIBRATION

Perform this calibration procedure when One Touch Cal is enabled in
the System Setup menu.

If using a field cable, install the sensor guard onto the probe. Moisten
the sponge in the grey calibration/storage sleeve with a small amount
of water and install it over the sensor guard. The sleeve should be
moist, but should not have excess water that could cause water
droplets to get on the membrane. The storage sleeve ensures venting
to the atmosphere.

If using the ProBOD sensor/cable assembly, place the probe in 300
ml BOD bottle with a small amount of water (1/8 inch or 0.3 cm). The
dissolved oxygen and temperature sensors should not be immersed
in water.

If the calibration/storage sleeve is not available, substitute with a
chamber of 100% relative humidity, vented to the atmosphere (not
completely sealed).

Power the instrument on and wait approximately 5 to 15 minutes for
the storage chamber to become completely saturated and to allow the
sensor to stabilize if using a Polarographic sensor. If using a Galvanic
sensor, wait approximately 5 to 10 minutes for the chamber to become
completely saturated. Auto Shutoff time should be disabled or set to
at least 20 minutes, see System Setup menu for more information on
adjusting the Auto Shutoff.

Ensure the barometer reading is accurate. If necessary, perform a
barometer calibration.

Press and hold the Calibrate
will indicate Calibrating %DO on the display and automatically
calibrate the sensor to the barometer and salinity correction values.
This may take up to 2 minutes depending on the age of the sensor
and membrane. You may press the Cal key at this time to cancel the
calibration.

key for 3 seconds. The Pro20/Pro20i

18

Calibration Successful will display for a few seconds to indicate a
successful calibration and then the instrument will return to the run
screen.

If the calibration is unsuccessful, an error message will display on the
screen. Press the Cal key to exit the calibration error message and
return to the run screen. See the Troubleshooting guide for possible
solutions.

Calibrating in Percent (DO%)

Perform this calibration procedure when One Touch Cal is disabled in
the System Setup menu.

Prepare a 100% humid environment for the sensor as described in the
previous calibration section.

Power the instrument on and wait approximately 5 to 15 minutes for
the storage chamber to become completely saturated and to allow the
sensor to stabilize if using a Polarographic sensor. If using a Galvanic
sensor, wait approximately 5 to 10 minutes for the chamber to become
completely saturated. Auto Shutoff time should be disabled or set to
at least 20 minutes, see System Setup menu for more information on
adjusting the Auto Shutoff.

Ensure the barometer reading is accurate. If necessary, perform a
barometer calibration.

Press and hold the Calibrate
press enter

temperature readings along with the % calibration value. The %
calibration value is based on the barometer reading.

Wait at least 3 seconds, then, once the DO% and temperature readings
are stable, press enter to complete the calibration. Or, press the Cal
key to cancel the calibration.

Calibration Successful will display for a few seconds to indicate a
successful calibration and then the instrument will return to the run
screen.

If the calibration is unsuccessful, an error message will display on the
screen. Press the Cal key to exit the calibration error message and
return to the run screen. See the Troubleshooting guide for possible
solutions.

. The Pro20/Pro20i will display the current DO% and

key for 3 seconds. Highlight % and

19

Calibrating in Percent (DO Local% Enabled)

Perform this calibration procedure when DO Local% is enabled in the
System Setup menu.

Prepare a 100% humid environment for the sensor as described in the
One Touch Calibration section.

Power the instrument on and wait approximately 5 to 15 minutes for
the storage chamber to become completely saturated and to allow the
sensor to stabilize if using a Polarographic sensor. If using a Galvanic
sensor, wait approximately 5 to 10 minutes for the chamber to become
completely saturated. Auto Shutoff time should be disabled or set to
at least 20 minutes, see System Setup menu for more information on
adjusting the Auto Shutoff.

Ensure the barometer reading is accurate. If necessary, perform a
barometer calibration.

Press and hold the Calibrate
automatically highlighted, press enter

display the current DO% and temperature readings along with the %
calibration value. The % calibration value will always be 100% for DO
Local%.

Wait at least 3 seconds, then, once the DO% and temperature readings
are stable, press enter to complete the calibration. Or, press the Cal
key to cancel the calibration.

Calibration Successful will display for a few seconds to indicate a
successful calibration and then the instrument will return to the run
screen.

If the calibration is unsuccessful, an error message will display on the
screen. Press the Cal key to exit the calibration error message and
return to the run screen. See the Troubleshooting guide for possible
solutions.

key for 3 seconds. %Local will be

. The Pro20/Pro20i will

Calibrating in mg/L

Power the instrument on and place the sensor into a sample that
has been titrated to determine the dissolved oxygen concentration.
Continuously stir or move the probe through the sample at a rate

20

of at least ½ foot per second (16 cm per second) during the entire
calibration process. A stir plate may be helpful in this calibration.
Allow the dissolved oxygen and temperature readings to stabilize. This
may take 5 to 15 minutes, depending on the age of the instrument,
type of sensor, and condition of the sensor.

Press the Calibrate

Use the up and down arrow keys to adjust the mg/L reading to the value
of the titrated sample. Press enter to confirm the value and calibrate or
press the Cal key to cancel the calibration.

Calibration Successful will display for a few seconds to indicate a
successful calibration and then the instrument will return to the run
screen.

If the calibration is unsuccessful, an error message will display on the
screen. Press the Cal key to exit the calibration error message and
return to the run screen. See the Troubleshooting guide for possible
solutions.

key. Highlight mg/L and press enter .

SALINITY COMPENSATION CALIBRATION

The Pro20/Pro20i uses a user inputted salinity value in ppt (parts per
thousands) to compensate dissolved oxygen mg/L values. The salinity
compensation value entered in the Pro20/Pro20i should be the salinity
value of the water you are testing.

To adjust the salinity compensation value, use the up or down arrow
keys to highlight the salinity box on the run screen, and then press
enter (Figure 10). Next, use the up or down arrow keys to adjust the
salinity compensation value to the salinity of the water you are testing.
You may enter a value between 0.0 and 70.0 parts per thousand (ppt).
Press enter to confirm and to save the new salinity compensation value.

The salinity compensation value can be adjusted any time without the
need to recalibrate dissolved oxygen.

21

Figure 10, Salinity box highlighted

TAKING MEASUREMENTS

Before taking measurements, be sure the instrument has been
calibrated to ensure the most accurate readings. Turn the instrument
on and wait 5-15 minutes if using a polarographic sensor. If using a
field cable/sensor, install the sensor guard to protect the sensor and
membrane. Place the probe in the sample to be measured and give the
probe a quick shake to release any air bubbles. Allow the temperature
readings to stabilize. Next, stir the probe in the sample to overcome the
stirring dependence of the dissolved oxygen sensor. You must provide
at least 6 inches (16 cm) per second of water movement. Once the
values plateau and stabilize you may record the measurement and/or
store the data set. The dissolved oxygen reading will drop over time if
stirring is ceased. If placing the DO sensor into a stream or fast flowing
waters it is best to place it perpendicular to the flow and NOT facing
into the flow.

If using the DO sensor in an aeration tank/basin it is helpful to make
sure bubbles do not burst on the membrane. This may cause unstable
readings to occur. You should be able to prevent this by pointing the
sensor upwards so it’s facing the sky and twist tying, zip tying, or rubber
banding the bulkhead to the cable. Essentially making a simple curve
to the cable without bending or breaking the cable will allow you to
lower the sensor into the aeration tank while the sensor points skyward
and the bubbles are no longer bursting on the membrane surface.

22

SAVING AND VIEWING DATA

The Pro20/Pro20i can store 50 data sets in non-volatile memory for
later viewing. A data set includes the values currently on the display,
i.e. temperature in Celsius or Fahrenheit and dissolved oxygen in %
and/or mg/L or ppm. Each data point is referenced with a data set
number, 01 through 50.

The Pro20/Pro20i can not communicate to a PC via a Pro Plus
communications saddle. Connecting the Pro20/Pro20i to a

i

communication saddle may cause erratic instrument behavior.

SAVING DATA

From the run screen, use the up or down arrow keys to highlight
the Save box and press enter

instrument will indicate the data set is saved and display the saved
data set’s number (Figure 11).

to save the current readings. The

Figure 11, data set saved.

The instrument will display ‘Memory Full’ if all 50 data sets have been
saved and you attempt to save another data set.

VIEWING AND ERASING SAVED DATA – DATA MODE

Data mode allows you to view and erase saved data. From the run
screen, use the up or down arrow keys to highlight Data and press
enter to access data mode. Note that the function boxes at the bottom
of the display are different in data mode (Figure 12).

23

Figure 12, Data mode.

Viewing Data

Once in data mode, use the up and down arrow keys to view saved data
sets in sequential order or press enter to access the bottom functions.
After accessing the bottom functions, highlight the Data box and press
enter to regain access to viewing data. The data set that is displayed
will be indicated by the data set number, 01 through 50.

Erasing Data

While viewing saved data, press the enter key to access the function
boxes at the bottom of the display. Next, use the up or down arrow
keys to highlight Erase, then press enter. The instrument will give you
the option to erase one or all data sets (Figure 13).

Figure 13, Erase data mode.

Use the up or down arrow key to select Erase Data Set, Erase All Sets,
or the ESC-Exit function box, then press enter to confirm.

24

Select ESC-Exit and press enter to exit erase mode without erasing any
data.

Select Erase Data Set and press enter to erase the data set that was
displayed before entering erase mode. For example, if data set 12 was
displayed before entering erase mode, and Erase Data Set is selected,
Data Set 12 will be erased from memory and the sets AFTER that
number will move up to keep them sequential. So, if there were 15
records and number 12 is erased then 13 becomes 12, 14 becomes
13, and 15 becomes 14. The instrument will return to data mode after
erasing one data set.

Select Erase All Data Sets and press enter to clear the Pro20/Pro20i
memory and return to data mode.

Exiting Data Mode

While in Data mode, press enter to access the bottom functions. Next,
highlight the ESC-Exit box and press enter to return to the Run screen.

PRINCIPLES OF OPERATION

The polarographic sensor consists of a silver body as the anode and
a circular gold cathode embedded in the end. The galvanic sensor
consists of a zinc anode and silver cathode. The polarographic sensor
requires an applied voltage for operation while the galvanic sensor
electrode potentials are dissimilar enough to reduce oxygen with
applied voltage.

Both sensors have a thin semi-permeable membrane, stretched over
the sensor, which isolates the electrodes from the environment, while
allowing gases to enter. In operation, this end of the sensor is filled
with a solution of electrolyte containing a small amount of surfactant
to improve wetting action.

When a polarizing voltage is applied to the polarographic sensor
electrodes, oxygen that has passed through the membrane reacts at
the cathode causing a current to flow. This same reaction takes place
with the galvanic sensor without the applied voltage.

For both polarographic and galvanic DO sensors, oxygen diffuses
through the membrane at a rate proportional to the oxygen pressure
difference across it. Since oxygen is rapidly consumed at the cathode,
it can be assumed that the oxygen pressure inside the membrane is

25

zero. Hence, the amount of oxygen diffusing through the membrane
is proportional to the absolute pressure of oxygen outside the
membrane. If the oxygen pressure increases, more oxygen diffuses
through the membrane and more current flows through the sensor. A
lower pressure results in less current.

CARE, MAINTENANCE AND
STORAGE

This section describes the proper procedures for care, maintenance
and storage of the sensors. The goal is to maximize their lifetime and
minimize down-time associated with improper sensor usage.

GENERAL MAINTENANCE

General Maintenance - O-Rings

The instrument utilizes o-rings as seals to prevent water from entering
the battery compartment and the sensor ports. Following the
recommended procedures will help keep your instrument functioning
properly.

If the o-rings and sealing surfaces are not maintained properly, it is
possible that water can enter the battery compartment and/or sensor
ports of the instrument. If water enters these areas, it can severely
damage the battery terminals or sensor ports causing loss of battery
power, false readings and corrosion to the sensors or battery terminals.
Therefore, when the battery compartment lid is removed, the o-ring
that provides the seal should be carefully inspected for contamination
(e.g. debris, grit, etc.) and cleaned if necessary.

The same inspection should be made of the o-rings associated with
the dissolved oxygen sensor connector when it is removed. If no dirt or
damage to the o-rings is evident, then they should be lightly greased
without removal from their groove. However, if there is any indication
of damage, the o-ring should be replaced with an identical o-ring. At
the time of o-ring replacement, the entire o-ring assembly should be
cleaned.

To remove the o-rings:
Use a small, flat-bladed screwdriver or similar blunt-tipped tool to
remove the o-ring from its groove. Check the o-ring and the groove
for any excess grease or contamination. If contamination is evident,
clean the o-ring and nearby plastic parts with lens cleaning tissue or

26

equivalent lint-free cloth. Alcohol can be used to clean the plastic
parts, but use only water and mild detergent on the o-ring itself. Also,
inspect the o-rings for nicks and imperfections.

Using alcohol on o-rings may cause a loss of elasticity and
may promote cracking.

i

Do not use a sharp object to remove the o-rings. Damage to
the o-ring or the groove may result.

Before re-installing the o-rings, make sure to use a clean workspace,
clean hands, and avoid contact with anything that may leave fibers on
the o-ring or grooves. Even a very small amount of contamination (hair,
grit, etc.) may cause a leak.

To re-install the sensor o-rings:

Place a small amount of o-ring grease between your thumb and index
finger. (More grease is NOT BETTER!)

Draw the o-ring through the grease while pressing the fingers together
to place a very light covering of grease to the o-ring. Place the o-ring
into its groove making sure that it does not twist or roll.

Use the previously grease-coated finger to once again lightly go over
the mating surface of the o-ring.

Do not over-grease the o-rings. The excess grease may collect
grit particles that can compromise the seal. Excess grease
can also cause the waterproofing capabilities of the o-ring to

i

diminish, potentially causing leaks. If excess grease is present,
remove it using a lens cloth or lint-free cloth.

General Maintenance - DO Sensor Port

It is important that the entire sensor connector end be dry when
installing, removing, or replacing. This will prevent water from entering
the port. Once a sensor is removed, examine the connector inside
the port. If any moisture is present, use compressed air to completely
dry the connector or place directly in front of a steady flow of fresh

27

air. If the connector is corroded, contact YSI Technical Support or the
Authorized dealer where you purchased the instrument.

Remove sensors upside down (facing the ground) to help

i

prevent water from entering the port upon removal.

SENSOR MAINTENANCE

Sensor Maintenance - Temperature

You must keep the temperature portion of the sensor free of build up.
Other than that, the sensor requires no maintenance. A toothbrush can
be used to scrub the temperature sensor if needed.

Sensor Maintenance - Dissolved Oxygen

Membrane Cap Installation

The DO sensor (Polarographic and Galvanic) is shipped with a dry,
protective red cap that will need to be removed before using. Remove
the protective cap or used membrane cap and replace it with a new
membrane cap following these instructions:

Remove the sensor guard to access the sensor.

Remove the protective red cap or unscrew and remove
any old membrane cap by holding the sensor when
unscrewing the membrane cap and discard.

Thoroughly rinse the sensor tip with distilled or
deionized water.

Fill a new membrane cap with O2 sensor
solution that has been prepared according
to the directions on the bottle. Be very
careful not to touch the membrane surface.

Lightly tap the side of the membrane cap to
release bubbles that may be trapped.

28

Thread the membrane cap onto the sensor. It is
normal for a small amount of electrolyte to overflow.

Replace the sensor guard.

Polarographic Sensors – Model # 605203

The KCl (potassium chloride) solution and the membrane cap should
be changed at least once every 30 days during regular use. In addition,
the KCl solution and membrane should be changed if (a) bubbles
are visible under the membrane; (b) significant deposits of dried
electrolyte are visible on the membrane; and (c) if the sensor shows
unstable readings or other sensor-related symptoms.

Figure 11, DO sensor with membrane removed.

During membrane changes, examine the gold cathode at the tip of
the sensor and the silver anode along the shaft of the sensor. If either
the silver anode is black in color or the gold cathode is dull, the sensor
may need resurfaced using the fine sanding disks included in the
membrane kit. Do not sand the electrode every membrane change as
this is not routine maintenance. In fact, visually, the anode may appear
tarnished and operate just fine. YSI recommends using the 400 grit
wet/dry sanding disks after a membrane change if the sensor has
difficulty stabilizing or calibrating.

29

To clean and resurface the sensor, follow the instructions below.

Gold Cathode

For correct sensor operation, the gold cathode must be textured
properly. It can become tarnished or plated with silver after extended
use. Never use chemicals or abrasives that have not been recommended
or supplied by YSI.

First dry the sensor tip completely with lens cleaning tissue. Wet
a sanding disc and place it face up in the palm of you hand. Next,
with your free hand, hold the sensor in a vertical position, tip down.
Place the sensor tip directly down on the sanding disc and twist it in a
circular motion to sand the gold cathode. The goal is to sand off any
build-up and to lightly scratch the cathode to provide a larger surface
area for the O
the sanding disc are sufficient to remove deposits and for the gold
to appear to have a matte finish. Rinse thoroughly and wipe the gold
cathode with a wet paper towel before putting on a new membrane
cap. If the cathode remains tarnished, contact YSI Technical Support or
the Authorized dealer where you purchased the instrument.

Silver Anode

After extended use, a thick layer of Silver Chloride (AgCl) builds up on
the silver anode reducing the sensitivity of the sensor. The anode must
be cleaned to remove this layer and restore proper performance. The
cleaning can be chemical and/or mechanical:

solution under the membrane. Usually, 3 to 4 twists of

2

Chemical cleaning: Remove the membrane cap and rinse the sensor
with deionized or distilled water. Soak the sensing section of the
sensor in a 14% ammonium hydroxide solution for 2 to 3 minutes or
in a 3% ammonia solution overnight for 8-12 hours (most household
ammonia cleaners are typically around 3%). Rinse heavily in cool tap
water followed by a thorough rinsing with distilled or deionized water.
The anode should then be thoroughly wiped with a wet paper towel to
remove the residual layer from the anode. You can smell the tip of the
sensor to help ensure all the ammonia has been rinsed off. Trapping
residual ammonia under the new membrane cap can quickly tarnish
the electrode and/or give false readings.

Chemical cleaning should be performed as infrequently as

i

possible. First attempt a membrane change and recalibrate. If
a new membrane does not resolve the problem, then proceed
with cleaning.

30

Mechanical cleaning: In order to sand the silver anode along the shaft
of the sensor, simply hold the sensor in a vertical position. Wet the
sanding disc and gently wrap it around the sensor and twist it a few
times to lightly sand the anode (the goal is to simply sand off any
build-up without scratching or removing layers of the anode itself).
Usually, 3 to 4 twists of the sanding disc are sufficient to remove
deposits. However, in extreme cases, more sanding may be required
to regenerate the original silver surface.

After completing the sanding procedure, repeatedly rinse the electrode
with clean water and wipe with lens cleaning tissue to remove any grit
left by the sanding disc. Thoroughly rinse the entire tip of the sensor
with distilled or deionized water and install a new membrane.

IMPORTANT: Be sure to: (1) Use only the fine sanding discs

i

provided and (2) Sand as mentioned in the above procedures.
Not adhering to either of these instructions can damage the
electrodes.

If this procedure is unsuccessful, as indicated by improper sensor
performance, contact YSI Technical Support or the Authorized dealer
where you purchased the instrument.

Galvanic Sensors – Model # 605202

We recommend that the Sodium Chloride (NaCl) solution and the
membrane cap be changed at least once every 60 days during regular
use. In addition, the NaCl solution and membrane should be changed
if (a) bubbles are visible under the membrane; (b) significant deposits
of dried electrolyte are visible around the membrane; and (c) if the
sensor shows unstable readings or other sensor-related symptoms.

The Galvanic dissolved oxygen sensor is continuously reducing
oxygen even when the display of the instrument is not active. This
factor allows the sensor to be used with no warm-up period as soon as
the instrument is powered on (instant on DO). However, because the
sensor is “on” all the time, some solid from the oxidation of the zinc
anode will form in the electrolyte within 1-2 weeks of activation. Small
amounts of the solid will generally cause no performance problems,
but excessive amounts may result in jumpy dissolved oxygen readings.
The rate of solid formation is dependent on the type of membrane
installed. The formation of solids based on membrane type typically
form more rapidly with 5913 (1.25 mil PE), and less rapid with 5914 (2
mil PE).

31

The Galvanic DO sensor solution will appear milky white after

i

use but will NOT affect the accuracy of the sensor unless there
is excessive build up. The color change is acceptable and
normal as long as DO readings remain stable.

At the time the membrane cap is changed, YSI recommends that you
rinse the anode (silver shaft of the sensor) with purified water and
wipe with a clean paper towel. If white deposits are evident on the
anode after cleaning, YSI recommends that you remove this material
by sanding the anode with the sandpaper disk included in the
membrane kit. Follow the “Mechanical Cleaning” instructions under
the Polarographic Silver Anode section.

IMPORTANT: Be sure to: (1) Use only the fine sanding discs
provided and (2) Sand as mentioned in the above procedures.
Not adhering to either of these instructions can damage the
electrodes.

i

WARNING: DO NOT PERFORM THE POLAROGRAPHIC
CHEMICAL CLEANING ON A GALVANIC SENSOR.

If this procedure is unsuccessful, as indicated by improper sensor
performance, contact YSI Technical Support or the Authorized Dealer
where you purchased the instrument.

SENSOR STORAGE

SHORT TERM STORAGE

The instrument is supplied with a grey calibration/storage sleeve that
slides over the probe guard. The sleeve is used for short-term storage
(less than 30 days). Be sure to keep a small amount of moisture (tap
water) on the sponge in the sleeve during storage. This is simply done
to maintain a 100% water saturated air environment which is ideal for
short-term sensor storage. The sensors should not be submersed in
water. The intent is to create a humid air storage environment.

LONG TERM STORAGE

Dissolved oxygen sensors (Polarographic and Galvanic) should always
be stored long term in a dry state. When storing for more then 30 days,
remove the membrane cap and thoroughly rinse the sensor. Once the
sensor has been rinsed either blow it dry with compressed air or allow

32

to air dry completely. Use a clean, dry new membrane cap to screw
over the sensor to keep it dry and to protect the anode and cathode.

After storing the sensor for a long period of time it is necessary to
“condition” the sensor by putting a new membrane with electrolyte
solution on the sensor.

Long Term Storage Temperature: -5 to 70°C (23 to 158°F)

TROUBLESHOOTING

Symptom Possible Solution

Instrument will not
calibrate; instrument
displays “Calibration
Over”, “Calibration
Under”, or “Unstable
Reading” during
calibration.

1. Verify barometer reading.

2. Verify correct sensor and membrane type
selection in the System Setup menu.

3. Calibration sleeve may not be 100% water
saturated, ensure sponge is moisten.

4. Ensure adequate sample movement if
performing mg/L or ppm calibration.

5. Allow sufficient stabilization time for
dissolved oxygen and temperature AND
wait at least 3 seconds before confirming
a DO % or DO %Local calibration.

6. Replace membrane and electrolyte.

7. Clean sensor electrodes.

8. Return system for service.

Instrument will
not turn on, a
battery symbol
appears, or “Critical
Shutdown” displays
on the screen.

Barometer reads
over/under,
Dissolved Oxygen
and Temperature
display Over/Undr,
and pressing Cal
key results in a
Barometric Pressure
Over/Undr message.

1. Low battery voltage, replace batteries.

2. Batteries installed incorrectly, check battery
polarity.

3. Return system for service.

1. Barometer failure, return system for service.

33

Symptom Possible Solution

Instrument readings
are inaccurate.

1. Verify correct sensor/membrane type
selection in the System Setup menu.

2. Verify calibration, barometer reading, and
salinity settings are correct and recalibrate.

3. Verify accurate temperature readings.

4. Sample temperature is over 45 ºC, the
temperature compensation range.

5. Probe may not have been in 100%
water saturated air during calibration
procedure. Moisten sponge in
calibration sleeve and recalibrate.

6. Replace membrane and
electrolyte, recalibrate.

7. Clean sensor electrodes.

8. Return system for service.

Dissolved Oxygen
values display Over or
Undr on run screen.

1. Verify correct sensor/membrane type
selection in the System Setup menu.

2. If using a polarographic sensor,
allow instrument to warm up for
5 – 15 minutes before use.

3. Sample O2 concentration is more
than 50 mg/L or 500%, or less
than –0.02 mg/L or -0.3%.

4. Verify barometer and salinity settings
are correct and recalibrate.

5. Verify accurate temperature readings.

6. Replace membrane and
electrolyte. Recalibrate.

7. Clean sensor electrodes.

8. Return system for service.

Temperature values
display Over or Undr
on run screen.

1. Sample temperature is less than -5º
C or more than +55 oC . Increase or
decrease the sample temperature to
bring within the allowable range.

2. Return system for service.

34

SPECIFICATIONS

These specifications represent typical performance and are subject to
change without notice. For the latest product specification information,
please visit YSI’s website at ysi.com or contact YSI Tech Support.

Parameter Range Resolution Accuracy

Temperature -5 to 55°C* 0.1°C ± 0.3°C

23 to 113 °F 0.1 °F ± 0.6 ºF

Dissolved

Oxygen

Barometer 400.0

* Automatic Dissolved Oxygen Temperature Compensation Range is

-5 to 45 ºC
**Available barometer units include: mmHg, inHg, mbars, psi, or KPa
***For operating temperatures below 10 °C or above 40 °C, the
barometer must be recalibrated to maintain accuracy specification.

0 to 200% air
saturation

200 to 500%
air saturation

0 to 20 mg/L 0.1 or 0.01 mg/L,

20 to 50
mg/L

to 999.9
mmHg**

1% or 0.1%, user
selectable

1% or 0.1%, user
selectable

user selectable

0.1 or 0.01 mg/L,
user selectable

0.1 mmHg ± 5 mmHg within

± 2% of the reading
or ± 2% air saturation,
whichever is greater

± 6% of the reading

± 2% of the reading
or ± 0.2 mg/L,
whichever is greater

± 6% of the reading

5 °C of calibration
temperature***

ACCESSORIES / PART NUMBERS

Part Number Description

6050020 Pro20 Instrument

607120-1* Pro20i Instrument with integral (i.e. built-in) 1-meter

cable; includes temperature and a port for Dissolved
Oxygen

607120-4* Pro20i Instrument with integral (i.e. built-in) 4-meter

cable; includes temperature and a port for Dissolved
Oxygen

607120-10* Pro20i Instrument with integral (i.e. built-in) 10-meter

cable; includes temperature and a port for Dissolved
Oxygen

*All cables include a temperature sensor. Dissolved Oxygen sensors
are sold separately.

35

Part Number Description

607125 Pro20i instrument with integral (i.e. built-in) 4-meter

cable. Polarographic DO sensor included.

60520-1, -4, -10,

-20, or -30*

605202 Galvanic Dissolved Oxygen sensor; 5913 membrane

605203 Polarographic Dissolved Oxygen sensor; 5908

607203 Polarographic Dissolved Oxygen sensor; 5909

605780 ProBOD, Self-Stirring BOD sensor (Pro20 only)

603077 Flow cell

603056 Flow cell mounting spike

603075 Carrying case, soft-sided

603074 Carrying case, hard-sided

603069 Belt clip for clipping instrument onto belt

063517 Ultra clamp for instrument for clamping instrument

063507 Tripod for instrument

601205 Grease, o-ring

603062 Cable management kit, included with all 4, 10, 20,

605978 Cable weight, 4.9 oz, stackable

603070 Shoulder strap

605306 5908 Cap membrane kit, 1.25 mil PE (6 each),

605307 5909 Cap membrane kit, 2 mil PE (blue cap, 6

605913 5913 Cap membrane kit, 1.25 mil PE (yellow cap, 6

605914 5914 Cap membrane kit, 2 mil PE (blue cap, 6 each),

1, 4, 10, 20, or 30-meter cable for Pro20 instruments;
with temperature and a port for Dissolved Oxygen

kit is included

membrane kit included

membrane kit included

to lab counter or other surface

and 30-meter cables

includes electrolyte (yellow cap). Used with
Polarographic sensor.

each), includes electrolyte (blue cap). Used with
Polarographic sensor.

each), includes electrolyte. Used with Galvanic sen­sor.

includes electrolyte. Used with Galvanic sensor.

*All cables include a temperature sensor. Dissolved Oxygen sensors
are sold separately.

36

DECLARATION OF CONFORMITY

The undersigned hereby declares on behalf of the named manufacturer
under our sole responsibility that the listed product conforms to the
requirements for the listed European Council Directive(s) and carries the
CE mark accordingly.

Manufacturer: YSI Incorporated

1725 Brannum Lane
Yellow Springs, OH 45387
USA

Product Name: Pro20/Pro20i

Model Numbers

Instrument: Pro20 (6050020)

Pro20i (607120-1, 607120-4, 607120-10, 607125)

Pro20 Cables: 60520, 605780

Sensors: 605202, 605203, 607203

Conforms to the following:

Directives: EMC 2014/30/EU

RoHS 2011/65/EU
WEEE 2012/19/EU

Harmonized
Standards:

Supplementary
Information:

Authorized EU
Representative

• EN6136-1:2013

• EN61000-3-2:2014

• EN61000-3-3:2013

All performance met the operation
criteria as follows:

1. ESD, IEC 61000-4-2:2001

2. Radiated Immunity, IEC 61000-4-3:2006

3. Electrical Fast Transient (EFT), IEC 61000­4-4:2004, +Corr. 1:2006 + Corr. 2:2007

4. Radio Frequency, Continuous Conducted
Immunity, IEC61000-4-6:2006

5. IEC 6100-4-8:2001

Xylem Analytics UK Ltd
Unit 2 Focal Point, Lacerta Court, Works Road
Letchworth, Hertfordshire, SG6 1FJ UK

Signed: Lisa M. Abel Date: 19 September 2016
Title: Director of Quality

37

RECYCLING

YSI takes seriously the commitment to reducing our environmental
footprint in our course of doing business. Even though materials
reduction is the ultimate goal, we know there must be a concerted
effort to responsibly deal with materials after they’ve served a long,
productive life-cycle.

YSI’s recycling program ensures that old equipment is processed in an
environmentally friendly way, reducing the amount of materials going
to landfills.

Printed Circuit Boards are sent to facilities that process and reclaim as
much material for recycling as possible.
Plastics enter a material recycling process and are not incinerated or
sent to landfills.

Batteries are removed and sent to specialist battery recyclers for
dedicated metals.

When the time comes for you to recycle, follow the easy steps as
outlined at www.ysi.com/recycle.

BATTERY DISPOSAL

The Pro20/Pro20i is powered by alkaline batteries which the user
must remove and dispose of when the batteries no longer power the
instrument. Disposal requirements vary by country and region, and
users are expected to understand and follow the battery disposal
requirements for their specific locale.

38

CONTACT INFORMATION

ORDERING AND TECHNICAL SUPPORT

Telephone: [phone] (USA)
[phone] (Globally)
Monday through Friday, 8:00 AM to 5:00 ET

Fax: [phone] (orders)
[phone] (technical support)

Email: [e-mail]

Mail: YSI Incorporated
1725 Brannum Lane
Yellow Springs, OH 45387
USA

Internet: ysi.com

When placing an order please have the following available:

1.) YSI account number (if available)

2.) Name and phone number

3.) Purchase Order or Credit Card number

4.) Model Number or brief description

5.) Billing and shipping addresses

6.) Quantity

SERVICE INFORMATION

YSI has authorized service centers throughout the United States and
Internationally. For the nearest service center information, please
visit www.ysi.com and click ‘Support’ or contact YSI Technical Support
directly at 800-897-4151 ([phone]).

When returning a product for service, include the Product Return form
with cleaning certification. The form must be completely filled out for a
YSI Service Center to accept the instrument for service. The form may
be downloaded from www.ysi.com.

39

Item # 605597

Rev C

September 2016

©2016 YSI Incorporated.