SECTION 2 PREPARING THE METER ........................................................................................................................2
ALIBRATIO N /S TORAGE CHAMBER ............................................................................................................................3
2.5 H
AND STRAP...............................................................................................................................................................3
2.6 T
HE METER CASE .......................................................................................................................................................3
SECTION 3 PREPARING THE PROBE.........................................................................................................................4
3.1 C
HOOSING THE RIGHT MEMBRANE CAP.....................................................................................................................4
3.2 M
EMBRANE CAP INSTALL A TION.................................................................................................................................4
URNING THE INSTRUMENT ON .................................................................................................................................7
RASIN G STORED DATA............................................................................................................................................10
4.8 T
OGGLING BETWEEN %-AIR SATURATION AND MG/L...............................................................................................11
EADINGS FROM THE CAT HODE REDUCTI ON.....................................................................................................13
ORMATION OF AGCL AT THE ANODE ......................................................................................................................13
UNCTION OF THE EL ECTROLYTE .............................................................................................................................13
SECTION 6 MAINTENANCE OF THE MEA SENSOR...........................................................................................14
SECTION 9 WARRANTY AND REPAIR...................................................................................................................19
APPENDIX A - GENERAL SPECIFICAT I ONS..........................................................................................................24
APPENDIX B - REQUIRED NOTICE...........................................................................................................................26
APPENDIX C - ACCESSORIES AND REPLACEMENT PARTS............................................................................27
APPENDIX D - UNIT CONVERSION...........................................................................................................................28
APPENDIX E - OXYGEN SOLUBILI T Y T ABL E.......................................................................................................29
APPENDIX F - CALIBRATION VALUES TABLE.....................................................................................................31
i
Page 4
ii
Page 5
SECTION 1
SECTION 1INTRODUCTION
SECTION 1SECTION 1
The YSI Model 95 Handheld Dissolved Oxygen and Temperature Sy stem is a rugged, microprocessor based, digital meter with an attached YSI m icroelectrode array (MEA) dissolv ed oxygen
probe. The MEA sensor eliminates the need for stirring in most environmental applications
allowing measurement of DO in the field without an external stirring dev ice. I t also reduces
measurement errors caused by insufficient or inconsistent stirring .
The YSI Model 95 has the following features:
• Microprocessor control
• Minimal stirring dependence
• Low maintenance MEA DO probe
• Push-button calibration
• Cap membranes for easy membrane replacement
• Simultaneous display of temperature and DO in % air saturation or mg/L
• Automatic salinity com pensation w ith m anual entering of salinity value
• Automatic temperature com p ensation
• Data storage for 50 sets of readings with on screen recall
• Waterproof case (IP65)
The YSI Model 95 has a non-detachable, combination sensor available with cable lengths of 10, 25,
50 or 100 feet. The Model 95D has a detachable cable. The probe utilizes easy to install cap
membranes and the probe body has been manufactured with stainless steel to add rugged durability
and sinking weight. The silver anode of the MEA DO sensor requires no servicing for up to 10,000
hours (four years) of operation under normal operating conditions (no sulfite contam ination).
INTRODUCTION
INTRODUCTIONINTRODUCTION
The Model 95’s micro-processor allows the system to be easily calibrated with the press of a few
buttons. Additionally, the micro-processor performs a self-diagnostic routine each time the
instrument is turned on. The self-diagnostic routine provides useful information about the function
of the instrument and probe. For a list of these diagnostic codes, see Section 8, Troubleshooting.
A probe calibration/storage chamber is built into the instrument case. A small moist sponge in the
chamber provides a water-saturated air environment that is ideal for air calibration of the dissolved
oxygen probe. This chamber also provides a convenient place to store the probe when the system is
not in use. The Model 95 case is waterproof (rated to IP65) allowing operation in the rain without
damage to the instrument.
Six AA-sized alkaline batteries power the Model 95. A new set of alkaline batteries will provide
approximately 150 hours of continuous operation. When batteries need to be replaced, the LCD will
display a “LO BAT” message.
The YSI Model 95 is designed for use in environmental, aquaculture, and industrial applications
where accurate dissolved oxygen and tem perature measurements are desired with minim al stirring .
YSI IncorporatedModel 951
Page 6
SECTION 2
SECTION 2PREPARING THE METER
SECTION 2SECTION 2
2.1
2.1UNPACKING
2.12.1
When you unpack your new YSI Model 95 Handheld Dissolv ed Oxy g en and Tem perature Sy stem
for the first time, compare the packing list with the contents of the shipping box. If there is anything
missing or damaged, call the dealer from whom you purchased the Model 95. If y ou do not k now
which authorized dealers sold the system to you, call YSI Customer Service at 800-765- 4974 or
937-767-7241, and we'll be happy to help y ou.
2.2
2.2WARRANTY CARD
2.22.2
Please complete the Warranty Card and return it to YSI. The warranty card allows the entry of your
purchase of this instrument in our computer system. Once your purchase is recorded, you will
receive prompt, efficient service if any part of your YSI Model 95 needs repair during the warranty
period.
2.3
2.3BATTERIES
2.32.3
UNPACKING
UNPACKINGUNPACKING
WARRANTY CARD
WARRANTY CARDWARRANTY CARD
BATTERIES
BATTERIESBATTERIES
PREPARING THE METER
PREPARING THE METERPREPARING THE METER
There are a few things you must do to prepare your YSI Model 95 for use. First, locate the six AAsized alkaline batteries that were included. Use a screwdriver or a small coin to remove the
thumbscrew on the bottom of the instrument (see figure below). This thumbscrew holds the batterychamber cover in place. The battery-chamber cover is marked with the words "OPEN" and
"CLOSE."
NOTE: On some models, the battery cover thumbscrew may be unscrewed by hand (a screwdriver
may not be required).
Battery chamber
cover
Thumb screw
Polarity marking
O-rings
Hand strap
YSI IncorporatedModel 952
Page 7
Preparing the MeterSection 2
There is a small molded insert inside each of the two battery-chamber sleeves. These labels
illustrate the correct way to install the batteries into each sleeve of the battery- chamber.
CAUTION: It is very important that the batteries be installed ONLY as illustrated. The instrument
will not function and may be damaged if the batteries are installed incorrectly.
Turn the instrument on by pressing and releasing the ON/OFF button on the front of the
instrument. The liquid crystal display (LCD) should come on. Allow a few seconds for the
instrument to complete its diagnostic routine. If the instrument does not operate, consult Section 8,
Troubleshooting.
You may also want to take the instrument into a dark room and with the instrument ON, hold down
the LIGHT button. The instrument back light should illuminate the LCD so that the display can be
easily read.
2.4
2.4CALIBRATION/STORAGE CHAMBER
2.42.4
The Model 95 has a convenient calibration/storage
chamber built into the instrument’s side. This chamber
provides an ideal storage area for the probe during
transport and extended non-use. If you look into the
chamber, you should notice a small round sponge in the
bottom. Carefully put about 10 drops of clean water into
the sponge. Turn the instrument over and allow any
excess water to drain out of the chamber. The wet
sponge creates a 100% water saturated air environment
for the probe that is ideal for dissolved oxygen
calibration.
The hand strap (see figure on previous page) is designed to allow comfortable operation of the
Model 95 with minimum effort. If the hand strap is adjusted correctly, it is unlikely that the
instrument will be easily dropped or bumped from your hand.
To adjust the hand strap on the back of the meter, unsnap the vinyl cover and pull the two Velcro
strips apart. Place your hand between the meter and the strap and adjust the strap length so that your
hand is snugly held in place. Press the two Velcro strips back together and snap the vinyl cover
back into place.
2.6
2.6METER CASE
2.62.6
The meter case is sealed at the factory and is not intended to be opened, except by authorized
service technicians. Do not attempt to separate the two halves of the meter case as this may
damage the instrument, break the water-proof seal, and may void the manufacturer's
warranty.
YSI IncorporatedModel 953
HAND STRAP
HAND STRAPHAND STRAP
METER CASE
METER CASEMETER CASE
Figure 1
Page 8
SECTION 3
SECTION 3PREPARING THE PROBE
SECTION 3SECTION 3
The YSI Model 95 dissolved oxygen probe is shipped wet with a shipping membrane installed. This
protective membrane cap on the probe tip must be removed and replaced with a new membrane cap
filled with MEA probe solution before using the probe. Follow the instructions below to install the
new membrane cap.
3.1
3.1CHOOSING THE CORRECT MEMBRANE CAP
3.13.1
Two different membrane caps are available for the Model 95. The YSI Model 9501 Membrane Cap
Kit is supplied with the Model 95. This kit contains six 0.5 mil (.0005") membrane caps and a bottle
of MEA probe solution (KCl).
NOTE: YSI 9501 Membrane Caps offer the fastest response to changes in DO and are
recommended by YSI for most applications.
For conditions with low flow or stagnant water, a 1 mil (.001") mem brane is av ailable (YSI Model
9502 Membrane Cap Kit). This membrane requires less stirring than the 9501, but has a m uch
slower response. Use this membrane when minimal stirring (<2"/sec) is available.
3.2
3.2MEMBRANE CAP INSTALLATION
3.23.2
CHOOSING THE CORRECT MEMBRANE CAP
CHOOSING THE CORRECT MEMBRANE CAPCHOOSING THE CORRECT MEMBRANE CAP
MEMBRANE CAP INSTALLATION
MEMBRANE CAP INSTALLATIONMEMBRANE CAP INSTALLATION
PREPARING THE PROBE
PREPARING THE PROBEPREPARING THE PROBE
WARNING: Use only YSI MEA probe solution in the m em brane cap. Any other solution will
damage the MEA sensor.
To install a new membrane cap on your YSI Model 95 dissolv ed oxy g en probe:
1. Unscrew and remove the probe sensor guard (see Figure 2 ).
2. Unscrew and remove the old mem brane cap.
3. Thoroughly rinse the sensor tip with distilled water.
4. Hold the membrane cap and add 8 to 9 drops of MEA probe solution (about half full).
5. Tap the bottom of the cap with your finger a few times to remove any trapped air bubbles.
CAUTION: Do not touch the membrane surface.
6. Screw the membrane cap onto the probe tightly by hand (to prevent leakage of electrolyte). A
small amount of probe solution should overflow.
7. Shake off any excess probe solution and rinse the stainless steel thoroughly with distilled water
to prevent corrosion.
YSI IncorporatedModel 954
Page 9
Preparing the ProbeSection 3
Fill new membrane
cap with 8-9 drops
of MEA probe
solution.
Unscrew guard
Unscrew cap
Tap cap with finger
to remove bubbles.
Screw cap on
tightly by hand
Screw guard on
tightly by hand
Figure 2
WARNING: Use only YSI MEA probe solution in the membrane cap. Any other solution will
damage the MEA sensor.
YSI IncorporatedModel 955
Page 10
SECTION 4
SECTION 4OPERATION
SECTION 4SECTION 4
The following diagram is an overview of the operation of the Model 95. See the following sections
for details of operation.
OPERATION
OPERATIONOPERATION
Figure 3
YSI IncorporatedModel 956
Page 11
OperationSection 4
4.1
4.1TURNING THE
4.14.1
With the batteries installed correctly, press the ON/OFF button. The instrument will activate all
segments of the display for a few seconds, which will be followed by a self test procedure which
will last for several more seconds. During this power on self test sequence, the instrument’s
microprocessor is verifying that the system is working properly. If the instrument were to detect a
problem, a continuous error message would be displayed. See the section entitled Troubleshooting
for a list of error messages.
NOTE: It is normal for an error to be displayed for a second or two when the system is first
4.2
4.2CALIBRATION
4.24.2
Dissolved oxygen calibration must be done in an environment with a known oxygen content. Since
the amount of oxygen in the atm osphere is k nown, it makes an excellent environment for calibration
(at 100% relative humidity). The calibration/storage chamber contains a moist sponge to create a
100% water saturated air environment.
TURNING THE INSTRUMENT ON
TURNING THE TURNING THE
turned on.
CALIBRATION
CALIBRATIONCALIBRATION
INSTRUMENT ON
INSTRUMENT ONINSTRUMENT ON
Before calibrating the YSI Model 95, complete the procedures discussed in the Preparing the
Meter and Preparing the Probe sections of this manual.
To accurately calibrate the YSI Model 95 you will need to k now the follow ing inform ation:
• The approximate altitude of the region in which you are located.
• The approximate salinity of the samples that you will be measuring. Fresh water has a salinity
of approximately zero. Sea water has a salinity of approximately 35 (parts per thousand, ppt). If
you are not certain what the salinity of the sample water is, use a YSI Model 30 SalinityConductivity-Temperature system to determine it.
1. Ensure that the sponge inside the instrument's
calibration chamber is wet. Insert the probe into the
calibration chamber.
2. Turn the instrument on by pressing the ON/OFF
button. Wait for the dissolved oxygen and
temperature readings to stabilize (usually 15
minutes is required after turning the instrument on).
If the instrument was already on, press the MODE
button until dissolved oxygen is displayed in mg/L
or % air saturation. To enter the calibration menu,
use two fingers to press and release both the UPARROW and DOWN ARROW buttons at the
same time (DOWN AR R OW slightly ahead).
Figure 4
YSI IncorporatedModel 957
Page 12
OperationSection 4
3. The LCD will prompt you to enter the local altitude in hundreds of feet. Use the arrow keys to
increase or decrease the altitude. When the proper altitude appears on the LCD, press the
ENTER button once.
EXAMPLE: Entering the number 12 here indicates 1200 feet.
4. The LCD will prompt you to enter the salinity of the sample(s) that you will be measuring. You
can enter any number from 0 to 80 (ppt). Use the arrow keys to increase or decrease the salinity
setting. When the proper salinity appears on the LCD (zero for fresh water), press the ENTER
button.
5. The Model 95 should now display CAL in the lower left of the display, the calibration value
should be displayed in the lower right of the display and the current DO reading (before
calibration) should be on the main display. Make sure that the DO reading (large display) is
stable, then press the ENTER button. The display should read SAVE then should return to the
Normal Operation Mode.
For best results:
• Each time the Model 95 is turned off, re-calibrate before taking m easurements.
• Calibrate at a temperature within ±10°C of the sam ple temperature.
4.3
4.3MAKING MEASURMENTS
4.34.3
MAKING MEASURMENTS
MAKING MEASURMENTSMAKING MEASURMENTS
The Model 95 has four modes:
ØDissolved Oxygen % -- A measurement of oxygen in percent of air saturation (partial
pressure).
Ø Dissolved Oxygen mg/L -- A measurement of oxygen solubility in mg/L.
Ø Recall -- Allows previously stored data to be displayed.
Ø Erase all -- Allows ALL previously stored data to be deleted.
Temperature is displayed in both dissolved oxyg en m odes.
NOTE: When you turn the Model 95 off, it will “remember” which DO mode you used last and
will return to that mode the next time the instrum ent is turned on.
To change between the Model 95 modes, simply press and release the MODE button. The Model
95 will cycle through the modes as follows:
Dissolved Oxygen
in % with°C
Dissolved Oxygen
in mg/L with °C
RecallErase all
YSI IncorporatedModel 958
Page 13
OperationSection 4
4.4
4.4STIRRING
4.44.4
It is important to realize that even a small amount of stirring will improve the DO and temperature
response times in stagnant water, because the transfer process of heat and oxygen will be facilitated
by convection. Also, the MEA dissolved oxygen probe is not totally stirring independent due to the
consumption of oxygen at the sensor tip during measurement. When taking dissolved oxygen
measurements in totally stagnant samples, the probe must be moved through the sample at a rate of
2 inches per second to provide adequate stirring.
4.5
4.5SSSSAVING DATA
4.54.5
The Model 95 is equipped with a non-volatile memory that is capable of storing up to 50 different
sets of readings. Non-volatile means that you do not need to worry that your data will be lost due to
a power failure or interruption, such as when the batteries are removed. Each set consists of
dissolved oxygen in percent, dissolved oxygen in mg/L and temperature. The Model 95 will also
assign a site identity number to each set of readings to allow easy review of the data. This feature is
useful in situations where transcribing data is difficult or not available.
While dissolved oxygen is displayed on the screen (in
% or mg/L), depress the ENTER button and hold it
for approximately 2 seconds. The meter will flash
SAVE on the display along with the current site
identity (1 through 50) being used.
STIRRING
STIRRINGSTIRRING
AVING DATA
AVING DATAAVING DATA
When all 50 sites are full, the display will flash FULL
on the screen. This message will remain on the screen
(even after power down) until a button is pushed.
Once you have acknowledged the memory is full, any
subsequent saved data will begin overwriting existing
data starting with site #1. No additional warning will
be displayed.
4.6
4.6RECALLING STORED DATA
4.64.6
1. To put the Model 95 into the RECALL mode,
2. Depress the ENTER button to review the last set
RECALLING STORED DATA
RECALLING STORED DATARECALLING STORED DATA
depress the MODE button repeatedly until “rcl”
is displayed on the screen along with the site ID
number in the lower right corner.
of data that was saved. The Model 95 will display
the dissolved oxygen in % air saturation and
temperature. Another press of the ENTER button
will display the dissolved oxygen in mg/L and the
temperature.
SAVE
01
rcl
01
3. Depress the UP ARROW button to move up
YSI IncorporatedModel 959
Page 14
OperationSection 4
through the saved sets of data.
4. Depress the DOWN ARROW button to move down through the saved sets of data.
5. When you have finished recalling data, press MODE two tim es to return to normal operation.
NOTE: The Model 95 will recall data as a list. When the UP ARROW is depressed the Model 95
will display the Site ID# for the previously recorded date. For example: If you are reviewing Site
ID# 5 and the UP ARROW is depressed the Model 95 will display Site ID#4. If you are reviewing
Site ID# 5 and Site ID# 5 was the last set of data stored the DOWN ARROW button will display
Site ID# 1.
Here is an example of the Model 95 memory .
Site ID #1
Site ID #2
Site ID #3 If the UP ARROW button was pressed the Model 95 would display Site ID #2
Site ID #4
Site ID #5
4.7
4.7ERASING STORED DATA
4.74.7
1. To erase the data that is stored in the Model 95’s
2. Depress and hold the DOWN ARROW and
3. When the Model 95 has successfully erased data,
ERASING STORED DATA
ERASING STORED DATAERASING STORED DATA
memory, depress the MOD E button until the
Model 95 displays ErAS on the screen.
ENTER buttons simultaneously for
approximately 5 seconds.
the display reads DONE for 1 to 2 seconds. The
instrument will automatically change to normal
operation after completion and the next saved
data will be stored in site ID# 1.
ErAS
IMPORTANT: Using the erase function forever and completely erases data in all 50 site
ID’s. Do not use the erase function until all recorded data has been transcribed to an archive outside
the Model 95.
YSI IncorporatedModel 9510
Page 15
OperationSection 4
4.8
4.8TOGGLING BETWEEN %-AIR SATURATION AND MG/L
4.84.8
The UP ARROW key allows quick and convenient switching between the two DO parameters
without going through the instrument’s four modes (using the MODE key). Press the UP ARROW
key to toggle the DO reading betw een %- air saturation and mg/L.
4.9
4.9DISSOLVED OXYGEN FILTER
4.94.9
The Model 95 is equipped with a DO filter to help filter out instability and high frequency noise.
This feature is useful when measuring dissolved oxygen in an unstable environment such as a fast
moving stream or an aeration tank . The default option for the filter is off. To activ ate the filter, enter
the filter option menu by pressing both the DOWN ARROW and MODE keys togethe r (Ú key
slightly ahead). Operation procedures:
• Press both the DOWN ARROW and MODE keys
• Press the UP ARROW or DOWN ARROW ke y to
TOGGLING BETWEEN %-AIR SATURATION AND MG/L
TOGGLING BETWEEN %-AIR SATURATION AND MG/LTOGGLING BETWEEN %-AIR SATURATION AND MG/L
DISSOLVED OXYGEN FILTER
DISSOLVED OXYGEN FILTERDISSOLVED OXYGEN FILTER
together (ÚÚÚÚ key slightly ahead). The current status
of the filter is displayed, On or OFF, with a smaller
“FIL” displayed in the bottom right corner of the
screen.
On
change the current status of the filter option.
• Press ENTER to confirm the change.
• To abort any changes and exit the filter menu, press
the MODE key (instead of ENTER).
4.10
4.10 DISPLAY BACKLIGHT
4.104.10
At times it may be necessary to tak e measurements with the Model 95 in dark or poorly lit areas. To
help in this situation, the Model 95 comes equipped with a backlight that will illuminate the display
so that it can be easily read. To activate the backlight, press and hold the LIGHT button. The
display will remain lit as long as the button is depressed. When y ou let it up, the lig ht g oes out to
preserve battery life.
DISPLAY BACKLIGHT
DISPLAY BACKLIGHTDISPLAY BACKLIGHT
FIL
YSI IncorporatedModel 9511
Page 16
SECTION 5
SECTION 5PRINCIPLES OF O
SECTION 5SECTION 5
5.1
5.1MEA CLARK OXYGEN SENSOR
5.15.1
The MEA (microelectrrode array) is a steady-state Clark type polarographic (voltammetric)
dissolved oxygen sensor. The sensor is made of a silv er anode and a gold cathode (consisting of 100
very small electrodes, each measuring approximately 8 micrometers in diameter) and is separated
from the measured medium by a semi-permeable Teflon membrane. The small dimensions of each
individual micro surface consume a very small amount of oxygen. Large spacing between adjacent
microsurfaces allows for minimal overlap of diffusion layers from adjacent cathode surfaces. This
design produces the minimal stirring dependence of the MEA probe. The temperature sensing
MEA CLARK OXYGEN SENSOR
MEA CLARK OXYGEN SENSORMEA CLARK OXYGEN SENSOR
PRINCIPLES OF OPERATION
PRINCIPLES OF OPRINCIPLES OF O
PERATION
PERATIONPERATION
Temperature sensor
Anode (silver)
MEA Cathode (gold)
Figure 5
element (thermistor assembly) is mounted next to the oxygen sensor vertically (see Figure 1),
providing temperature reading s for the DO sy stem.
The membrane selectively allows oxygen to permeate into the sensor, but prevents most interfering
molecules and fouling materials from entering. Upon permeating through the membrane, oxygen is
reduced at the gold cathode. The current resulting from this reduction is diffusion-limited and is
proportional to the partial pressure of oxygen in the sample. The counter reaction is the oxidation of
silver at the anode/reference electrode that completes the overall electrolytic reaction in the chloride
medium (KCl electrolyte) behind the membrane. These reactions, at the cathode and the anode, are
as follows:
Cathode reaction:O
Anode reaction:Ag + Cl- ==> AgCl + e
+ 2H2O + 4e- ==> 4OH
2
-
-
YSI IncorporatedModel 9512
Page 17
Principals of OperationSection 5
5.2
5.2DO READINGS FROM THE CATHODE REDUCTION
5.25.2
The oxygen reduction current is sampled and processed, by the meter, and displayed as either %-air
saturation or mg/L. While the parameter of %-air (partial pressure) is independent of temperature
and salinity, mg/L (solubility of oxygen) is a function of temperature and salinity. The same %-air
reading (same partial pressure) would give a higher mg/L reading at a lower temperature than at a
higher temperature. The higher the salinity, the lower the solubility (mg/L) is for the same %-air
reading at the same temperature.
5.3
5.3FORMATION OF AgCl AT THE ANODE
5.35.3
While the oxygen reduction current passes through the internal circuit to be reported as the DO
reading, it also passes through the anode oxidizing the silver and forming a thin layer of silver
chloride. Furthermore, the oxidation of silver at the chloride medium provides a stable potential that
the cathode potential is referenced to (for instance, the polarization potential of the cathode is -1.0
V versus the potential of the Ag/AgCl redox couple at the silver anode). Since the current of the
MEA sensor is so small, there should not be any significant accumulation of AgCl at the anode for
3 to 4 years.
DO READINGS FROM THE CATHODE REDUCTION
DO READINGS FROM THE CATHODE REDUCTIONDO READINGS FROM THE CATHODE REDUCTION
FORMATION OF AgCl AT THE ANODE
FORMATION OF AgCl AT THE ANODEFORMATION OF AgCl AT THE ANODE
5.4
5.4FUNCTION OF THE EL
5.45.4
There are two main functions for the electrolyte:
Under normal operating conditions, such as measuring oxygen around 100%-air saturation (8.27
mg/L) at 25°C, the electrolyte should last up to 500 hours. This translates into about 62.5 working
days at 8 hours per day operation. The actual electrolyte life, however, may be shorter since, in
most environmental applications, membrane fouling determines the life of the
electrolyte/membrane.
FUNCTION OF THE ELECTROLYTE
FUNCTION OF THE ELFUNCTION OF THE EL
1. Supply the chloride (Cl
oxygen reduction at the cathode.
2. Provide the ionic conduction of electricity inside the cell, especially in the thin layer
between the gold cathode and the membrane.
ECTROLYTE
ECTROLYTEECTROLYTE
-
) to the anode/reference electrode for the counter reaction of the
YSI IncorporatedModel 9513
Page 18
SECTION 6
SECTION 6MAINTENANCE OF THE MEA SENSOR
SECTION 6SECTION 6
6.1
6.1ANODE SERVICE
6.16.1
Warning: Under no circumstances should ammonium hydroxide be used to clean the silver
anode. Ammonium hydroxide will permanently damage the condition of the MEA surface.
The MEA oxygen sensor is, in principle, the same as the conventional Clark oxygen sensor in that
the sensor is made of a silver anode and a gold cathode, but the cathode is a microelectrode array.
Since the current of the MEA oxygen sensor is so much sm aller (on av erag e 100 tim es sm aller) than
the current of YSI conventional oxygen sensors, consumption of the silver anode, due to the
formation of AgCl, is minimal during the lifetime of the probe. There should not be any significant
build-up of silver chloride at the surface of the anode for 3 to 4 years, therefore, the anode should
not require chemical cleaning. Howev er, if the surface of the silv er anode has become fouled, gently
wet sand it using 400 grit wet/dry sandpaper, rinse thoroughly with deionized or distilled water and
wipe with a wet paper towel until the dark layer is removed. The directions are as follows:
Anode Cleaning Procedures (See figure 6)
ü Rinse the sensor thoroughly after removing the membrane cap.
ü Use wet 400 grit sandpaper to sand away the top layer of the anode by wrapping the sandpaper
ANODE SERVICE
ANODE SERVICEANODE SERVICE
around the anode and gently rotating it until the dark lay er is removed.
MAINTENANCE OF THE MEA SENSOR
MAINTENANCE OF THE MEA SENSORMAINTENANCE OF THE MEA SENSOR
ü Rinse the anode thoroughly with deionized or distilled water and wipe with a w et paper towel.
ü Rinse the anode again with deionized or distilled water.
Anode
Wet
microcloth
Figure 6
6.2
6.2CATHODE SERVICE
6.26.2
Warning: Under no circumstances should the gold cathode surface (the MEA surface) be
sanded. Sanding will permanently damage the condition of the MEA surface.
If the MEA oxygen sensor exhibits erratic behavior, such as a current rise at a rate of 1%/hour or
very jumpy readings, it can be serviced by buffing. You can use a few light twists against the
surface with the wet microcloth mounted on the buffing tool provided in the 9503 reconditioning
kit.
CATHODE SERVICE
CATHODE SERVICECATHODE SERVICE
Cathode
Buffing Tool
Press lightly against
sensor surface
YSI IncorporatedModel 9514
Page 19
Maintenance of the MEA SensorSection 6
Note: The MEA sensor does not require buffing (cleaning) every time the membrane cap is
changed. Under normal operating conditions, the MEA sensor should be buffed no more than two
times per year.
Cathode Cleaning Procedures
ü Remove the mem brane cap and rinse the sensor thoroug hly with deionized or distilled water.
ü Place the microcloth on the buffing tool (self-adhesive). Wet the microcloth thoroughly with
deionized or distilled water.
ü Twist the buffing tool back and forth three times in opposite directions while lightly pressing
the buffing tool against the sensor surface (see figure 6).
ü Rinse the sensor surface well with deionized or distilled water after buffing.
6.3
6.3DISSOLVED OXYGEN PROBE PRECAUTIONS
6.36.3
Membrane life depends on usage.If the probe is properly maintained, one membrane cap should
last two to four weeks depending on how often the probe is used and the type of samples measured.
It is recommended that m embrane caps not be re-used.
1. To keep the electrolyte from drying out, store the probe in a moist environment, such as the
2. Erratic readings are a result of loose, wrinkled, damaged, or fouled membranes, or from large
(more than 1/4 of the circumference of the probe) bubbles in the electrolyte reservoir. If erratic
readings or evidence of membrane damage occurs, you should replace the membrane cap and
the KCl solution. The average replacement interval is tw o to four weeks.
3. If the membrane is coated with oxygen consuming (e.g. bacteria) or oxygen evolving organisms
(e.g. algae), erroneous readings may occur.
4. Chlorine, sulfur dioxide, nitric oxide, and nitrous oxide can affect readings by behaving like
oxygen at the probe. If you suspect erroneous readings, it may be necessary to determine if
these gases are the cause.
5. Avoid any environment that contains substances that may attack the probe materials. Some of
these substances are concentrated acids, caustics, and strong solvents. The probe materials that
come in contact with the sample include FEP Teflon, stainless steel, epoxy, polyetherimide and
the polyurethane cable covering.
6. Do not allow the probe to strike hard objects. The membrane or sensor inside may be damaged.
6.4
6.4PROBE STORAGE
6.46.4
For long term storage (4 weeks), remove the membrane cap, thoroughly rinse the MEA sensor with
deionized or distilled water and install a new membrane cap filled with MEA probe solution. Store
the sensor in a humid environment such as the calibration chamber with the wet sponge inside. Do
NOT store the probe dry.
PROBE STORAGE
PROBE STORAGEPROBE STORAGE
YSI IncorporatedModel 9515
Page 20
SECTION 7 DISCUSSION OF MEASUREMENT ERRORS
SECTION 7 DISCUSSION OF MEASUREMENT ERRORS
SECTION 7 DISCUSSION OF MEASUREMENT ERRORSSECTION 7 DISCUSSION OF MEASUREMENT ERRORS
There are three basic types of dissolved oxygen errors. Type 1 errors are related to limitations of
instrument design and tolerances of instrument components. These are primarily the meter linearity
and the resistor tolerances. Type 2 errors are due to basic probe accuracy tolerances, mainly
background signal, probe linearity, and variations in membrane temperature coefficient. Type 3
errors are related to the operator's ability to determine the conditions at the time of calibration. If
calibration is performed against more accurately known conditions, type 3 errors are appropriately
reduced.
Type 1 Errors
A. Meter linearity error: ±0.5% of full scale reading, or ±0.04 mg/l at 25° C whichev er is g reater.
B. Component and circuitry error: ±0.04 mg/l
Type 2 Errors
A. DO errors caused by temperature compensation for measurements at ±10°C from calibration
temperature: ±1% of 25° C (±0.08 mg/l)
B. DO errors caused by temperature measurement errors: A maximum ±0.2°C temperature error is
equal to ±0.5% (0.04mg/L at 25°C).
Type 3 Errors
A. Altitude: The maximum DO error caused by calibrating to altitude in increments of 100 feet:
±0.18% (< 0.015 mg/l at 25°C)
B. Humidity: Errors occur if calibration is performed at less than 100% humidity. The worst
possible case would be calibration at 0% humidity. The error varies with the calibration
temperature as follows:
It is unlikely that the actual error in any measurement will be the maximum possible error. A better
error approximation is obtained using a root mean squared (r.m .s.) calculation:
2
r.m.s. error = ±[1a
NOTE: This calculation is for a near extreme set of conditions.
If the probe is calibrated in water-saturated air, then type 3B errors (humidity), the largest error of
all types, is virtually eliminated and the maximum possible error is in the order of 0.1 mg/L for the
case of calibrating around 25°C.
YSI IncorporatedModel 9516
+ 1b2 + 2a2 + 2b2 + 3a2 + 3b2]½ mg/l
Page 21
SECTION 8
SECTION 8TROUBLESHOOTING
SECTION 8SECTION 8
TROUBLESHOOTING
TROUBLESHOOTINGTROUBLESHOOTING
SymptomPossible CauseAction
1. Instrument will not turn onA. Low battery voltage
B. Batteries installed wrong
C. Meter requires service
2. Instrument will not calibrate
3. Instrument "loc k s up"A. Instrument ha s r e c'd a shock
4. Dissolved Oxygen readings are
inaccurate
A. Membrane is fouled or damaged
B. Probe anode is fouled or da rk
C. Probe cathode is fouled
D. System requires service
B. Batteries are low or damaged
C. System requires service
A. Cal altitude is incorrect
B. P robe not in 100% water saturated
air during Cal proce dure
C. Membrane fouled or damage d
D. Probe anode is fouled or dark
E. Probe ca t hode is fouled
F. System requires service
A. Replace batteries (Section 2)
B. Check battery pola rity. (Section 2)
C. Return system for service (Section 9)
A. Replace membrane cap (Section 3)
B. Clean anode (Sec tion 6)
C. Buff cathode ( Se c tion 6)
D. Return system for service (Section 9)
A & B. Remove battery lid, wait 15
seconds for res e t, re place lid. (Section 2)
C. Return system for service (Section 9)
A. Recalibrate w/correct value (Section
4)
B. Moisten sponge & place in Cal
chamber w/ probe & Recal (Section 4)
C. Replace membrane cap (Section 3)
D. Clean anode (Section 6)
E. Buff cathode (Sec tion 6)
F. Return system for service (Section 9)
5. LCD displays "LO BAT"A. Batteries are low or damagedA. Replace batteries (Section 2)
6. Main Display reads “OVEr”
(Secondary displa y reads “ovr”)
(Secondary displa y reads “udr”)
7. Main display reads “PErr”A. Incorrect sequence of keystrokes.A. Refer to manual section for step by step
8. Main display reads “Err”
(Secondary displa y reads “ra”)
9. Main display reads “Err”
(Secondary displa y reads “ro”)
A. Temperature reading is >45°C
B. Temperature reading is <-5°C
C. DO temperature is >45°C
D. DO % saturation is > 500%
E. DO concentration is >50 m g /L
F. Probe current too high to calibrate
A. System has failed its RAM test check
procedure.
A. System has failed its ROM test check
procedure.
In all cases, check calibration values and
procedures. (Section 4)
If each of these were done correctly,
return instrument for service. (Section 9)
instruction for the function you are
attempting.
A. Turn instrument OFF and back ON
again.
B. Return the system for service (Section 9)
A.Turn instrument OFF and back ON
again.
B. Return the system for service (Section 9)
YSI IncorporatedModel 9517
Page 22
TroubleshootingSection 8
10. Main reads “Undr”Probe current too low to calibrate
10. Main display reads “ FAIL”
(Secondary displa y reads “eep”)
A. EEPROM has failed to respond in
time.
A. Return the system for service (Section 9)
11. Readings on main display don’t
change
A. Meter is in recall mode .A. Press MODE button to return to
Normal Operation ( Se c tion 4)
YSI IncorporatedModel 9518
Page 23
SECTION 9
SECTION 9WARRANTY AND REPAIR
SECTION 9SECTION 9
YSI Model 95 Dissolved Oxygen Meters are warranted for two years from date of purchase by the
end user against defects in materials and workmanship. YSI Model 95 probes and cables are
warranted for one year from date of purchase by the end user against defects in material and
workmanship. Within the warranty period, YSI will repair or replace, at its sole discretion, free of
charge, any product that YSI determ ines to be cov ered by this warranty .
To exercise this warranty, write or call your local YSI representative, or contact YSI Customer
Service in Yellow Springs, Ohio. 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 (i) failure to install,
operate or use the product in accordance with YSI’s written instructions, (ii) abuse or misuse of the
product, (iii) failure to maintain the product in accordance with YSI’s written instructions or
standard industry procedure, (iv) any improper repairs to the product, (v) use by you of defective or
improper components or parts in servicing or repairing the product, or (vi) 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 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.
WARRANTY AND REPAIR
WARRANTY AND REPAIRWARRANTY AND REPAIR
YSI,IncorporatedModel 9519
Page 24
Warranty and RepairSection 9
AUTHORIZED U.S. SERVICE CENTERS
AUTHORIZED U.S. SERVICE CENTERS
AUTHORIZED U.S. SERVICE CENTERSAUTHORIZED U.S. SERVICE CENTERS
North and East Region
YSI Incorporated • Repair Center • 1725 Brannum Lane • Yellow Springs, Ohio • 45387 • Phone:
(800) 765-4974 • (937) 767-7241• E -Mail: info@ysi.com
YSI IncorporatedModel 9520
Page 25
Warranty and RepairSection 9
INTERNATIONAL SERVICE CENTERS
INTERNATIONAL SERVICE CENTERS
INTERNATIONAL SERVICE CENTERSINTERNATIONAL SERVICE CENTERS
YSI Incorporated • Repair Center • 1725 Brannum Lane • Yellow Springs, Ohio • 45387 • Phone:
(937) 767-7241• E-Mail: info@ y si.com
SPECIALTY SERVICE CENTERS
SPECIALTY SERVICE CENTERS
SPECIALTY SERVICE CENTERSSPECIALTY SERVICE CENTERS
YSI IncorporatedModel 9521
Page 26
Warranty and RepairSection 9
CLEANING INSTRUCTIONS
CLEANING INSTRUCTIONS
CLEANING INSTRUCTIONSCLEANING INSTRUCTIONS
NOTE: Before they can be serviced, equipment exposed to biological, radioactive, or toxic
materials must be cleaned and disinfected. Biological contamination is presumed for any
instrument, probe, or other device that has been used with body fluids or tissues, or with waste
water. Radioactive contamination is presumed for any instrument, probe or other device that has
been used near any radioactive source.
If an instrument, probe, or other part is returned or presented for service without a Cleaning
Certificate, and if in our opinion it represents a potential biological or radioactive hazard, our
service personnel reserve the right to withhold service until appropriate cleaning, decontamination,
and certification has been completed. We will contact the sender for instructions as to the
disposition of the equipment. Disposition costs will be the responsibility of the sender.
When service is required, either at the user's facility or at YSI, the following steps must be taken to
insure the safety of our service personnel.
1. In a manner appropriate to each device, decontaminate all exposed surfaces, including any
containers. 70% isopropyl alcohol or a solution of 1/4 cup bleach to 1 gallon tap water are
suitable for most disinfecting. Instruments used with waste water may be disinfected with .5%
Lysol if this is more convenient to the user.
2. The user shall take normal precautions to prevent radioactive contamination and must use
appropriate decontamination procedures should exposure occur.
3. If exposure has occurred, the customer must certify that decontamination has been
accomplished and that no radioactivity is detectable by survey equipment.
4. Any product being returned to the YSI Repair Center, should be packed securely to prevent
damage.
5. Cleaning must be completed and certified on any product before returning it to YSI.
PACKING INSTRUCTIONS
PACKING INSTRUCTIONS
PACKING INSTRUCTIONSPACKING INSTRUCTIONS
1. Clean and decontaminate items to insure the safety of the handler.
2. Complete and include the Cleaning Certificate.
3. Place the product in a plastic bag to keep out dirt and packing m aterial.
4. Use a large carton, preferably the original, and surround the product completely with packing
material.
5. Insure for the replacement value of the product.
YSI IncorporatedModel 9522
Page 27
Warranty and RepairSection 9
Cleaning Certificate
Organization ________________________________
Department _________________________________
Address ___________________________________
City _______________ State ______ Zip ________
Country __________________
Model No. of Device ______ Lot Number _________
Contaminant (if known) _____________________
Cleaning Agent(s) used _____________________
Radioactive Decontamination Certified?
(Answer only if there has been radioactive exposure)
___ Yes ___ No
Cleaning Certified By _________________________
NameDate
YSI IncorporatedModel 9523
Page 28
APPENDIX A
APPENDIX AGENERAL SPECIFICATIONS
APPENDIX AAPPENDIX A
Materials: ABS, Stainless Steel, and other materials
Dimensions:
Height:9.5 inches(24.13 cm)
Thickness:2.2 inches(5.6 cm )
Width:3.5 inches max.(8.89 cm)
Weight:1.7 pounds (w/ 10’ cable)(.77 kg)
Display:2.3”W x 1.5”L(5.8 cm W x 3.8 cm L)
Power: 6 AA-size Alkaline Batteries (included)
Approximately 150 hours operation from each new set of batteries
Automatic shutoff after 4 hours without a key press
Water Tightness: Meets or exceeds IP65 standards
Operating Environment
Medium: fresh, sea, or polluted water and most other liquid solutions.
GENERAL SPECIFICATIONS
GENERAL SPECIFICATIONSGENERAL SPECIFICATIONS
Temperature: -5 to +45 °C
Depth: 0 to 10, 0 to 25, 0 to 50, or 0 to 100 feet (depending on cable length)
Storage Temperature: -5 to +55 °C
System Performance Specifications:
MeasurementRangeResolutionAccuracy
Temperature-5 to +45 °C0.1 °C
Dissolved Oxygen0 to 500 % Air Sat.
0 to 50 mg/L
DO Response Time:Application dependent. Typically 60 sec for 95% of the
change at 25°C
Temperature Response Time:Typically 95% of the chang e
Temperature Compensation:Automatic
0.1% Air Saturation
0.01 mg/L
± 0.2 °C
± 2% or ± 0.2 mg/L,
whichever is greater. 0 to
200% air.
+ 5% for 200% to 500% air
YSI IncorporatedModel 9524
Page 29
Salinity Compensation Range:0 to 80 ppt (compensation between 40 and 80 is based on
extrapolation)
Stirring Dependence:0.5-mil membrane: <5% error in stagnant water or <2% at a
flow rate of 2 in/sec at 120 nA nominal current
1-mil membrane: <3% error in stagnant water or <1% at a
flow rate of 2 in/sec at 100 nA nominal current
Data Storage: 50 points with ID number.
YSI IncorporatedModel 9525
Page 30
APPENDIX B
APPENDIX BREQUIRED NOTICE
APPENDIX BAPPENDIX B
The Federal Communications Commission defines this product as a computing device and requires
the following notice:
This equipment generates and uses radio frequency energy and if not installed and used properly,
may cause interference to radio and television reception. There is no guarantee that interference will
not occur in a particular installation. If this equipment does cause interference to radio or television
reception, which can be determined by turning the equipment off and on, the user is encouraged to
try to correct the interference by one or more of the following measures:
• re-orient the receiving antenna
• relocate the computer with respect to the receiver
• move the computer away from the receiver
• plug the computer into a different outlet so that the computer and receiver are on
different branch circuits.
If necessary, the user should consult the dealer or an experienced radio/television technician for
additional suggestions. The user may find the following booklet, prepared by the Federal
Communications Commission, helpful: "How to Identify and Resolve Radio-TV Interference
Problems." This booklet is available from the U.S. Government Printing Office, Washington, DC
20402, Stock No. 0004-000-00345- 4.
REQUIRED NOTICE
REQUIRED NOTICEREQUIRED NOTICE
YSI IncorporatedModel 9526
Page 31
APPENDIX C
APPENDIX CACCESSORIES AND REPLACEMENT PARTS
APPENDIX CAPPENDIX C
The following parts and accessories are available from YSI or any Franchise Dealer authorized by
YSI.
YSI Order NumberDescription
9501Replacement Membrane Cap Kit, 0.5 mil ( 6 each )
9502Replacement Membrane Cap Kit, 1 mil ( 6 each )
9503MEA Probe Reconditioning Kit
5520Carryin g C a s e, s mall (95-10 or 95-25 only)
5050Carryin g C a s e, medium (95- 50 or 95- 100)
059965Replacement Probe & Cable As s embly (10 feet)
059981Replacement Probe & Cable As s embly (25 feet)
059984Replacement Probe & Cable As s embly (50 feet)
059987Replacement Probe and Cable As s embly (100 feet)
059971Replacement Front Cas e C over
ACCESSORIES AND REPLACEMENT PARTS
ACCESSORIES AND REPLACEMENT PARTSACCESSORIES AND REPLACEMENT PARTS
055242Replacement Rear Case C ov er
055244Replacement Battery C over Kit
055204Replacement Case Gask et an d S crew
055219Calibration Chamber Sponge
030157Main Board Assembly
YSI IncorporatedModel 9527
Page 32
APPENDIX D
APPENDIX DUNIT CONVERSION
APPENDIX DAPPENDIX D
UNIT CONVERSION
UNIT CONVERSIONUNIT CONVERSION
Conversion Chart
To Convert FromToEquation
FeetMetersMultiply by 0.3048
MetersFeetMultiply by 3.2808399
Degrees CelsiusDegrees Fahrenheit(9/5oC)+32
Degrees FahrenheitDegrees Celsius5/9(oF-32)
Milligrams per liter (mg /l)Parts per million (ppm)Multiply by 1
YSI IncorporatedModel 9528
Page 33
APPENDIX E
APPENDIX EOXYGEN SOLUBILITY TABLE
APPENDIX EAPPENDIX E
OXYGEN SOLUBILITY TABLE
OXYGEN SOLUBILITY TABLEOXYGEN SOLUBILITY TABLE
Solubility of Oxygen in m g /l in Water Exposed to Water-Saturated Air at 760 mm Hg Pressure.
Salinity = Measure of quantity of dissolved salts in water.
Chlorinity = Measure of chloride content, by mass, of water.
0
S(
/00) = 1.80655 x Chlorinity (0/00)
Temp
o
C
0.014.6213.7312.8912.1011.3610.66
1.014.2213.3612.5511.7811.0710.39
2.013.8313.0012.2211.4810.7910.14
3.013.4612.6611.9111.2010.539.90
4.013.1112.3411.6110.9210.279.66
5.012.7712.0211.3210.6610.039.44
6.012.4511.7311.0510.409.809.23
7.012.1411.4410.7810.169.589.02
8.011.8411.1710.539.939.368.83
9.011.5610.9110.299.719.168.64
10.011.2910.6610.069.498.968.45
11.011.0310.429.849.298.778.28
12.010.7810.189.629.098.598.11
Chlorinity:0
Salinity:0
5.0 ppt
9.0 ppt
10.0 ppt
18.1 ppt
15.0 ppt
27.1 ppt
20.0 ppt
36.1 ppt
25.0 ppt
45.2 ppt
13.010.549.969.428.908.417.95
14.010.319.759.228.728.247.79
15.010.089.549.038.548.087.64
16.09.879.348.848.377.927.50
17.09.679.158.678.217.777.36
18.09.478.978.508.057.627.22
19.09.288.798.337.907.487.09
20.09.098.628.177.757.356.96
21.08.928.468.027.617.216.84
22.08.748.307.877.477.096.72
23.08.588.147.737.346.966.61
YSI IncorporatedModel 9529
Page 34
Oxygen Solubility TableAppendix E
Temp
o
C
Chlorinity:0
Salinity:0
5.0 ppt
9.0 ppt
10.0 ppt
18.1 ppt
15.0 ppt
27.1 ppt
20.0 ppt
36.1 ppt
24.08.427.997.597.216.846.50
25.08.267.857.467.086.726.39
26.08.117.717.336.966.626.28
27.07.977.587.206.856.516.18
28.07.837.447.086.736.406.09
29.07.697.326.966.626.305.99
30.07.567.196.856.516.205.90
31.07.437.076.736.416.105.81
32.07.316.966.626.316.015.72
33.07.186.846.526.215.915.63
34.07.076.736.426.115.825.55
35.06.956.626.316.025.735.46
36.06.843.526.225.935.655.38
25.0 ppt
45.2 ppt
37.06.736.426.125.845.565.31
38.06.626.326.035.755.485.23
39.06.526.225.985.665.405.15
40.06.416.125.845.585.325.08
41.06.316.035.755.495.245.01
42.06.215.935.675.415.174.93
43.06.125.845.585.335.094.86
44.06.025.755.505.255.024.79
45.05.935.675.415.174.944.72
* This table is provided for your information only. It is NOT required when calibrating the Model
95 in accordance with the instructions outlined in the section entitled Calibration
YSI IncorporatedModel 9530
Page 35
APPENDIX F
APPENDIX FCALIBRATION VALUES TABLE
APPENDIX FAPPENDIX F
Calibration values for various atmospheric pressures and altitudes.
Note: This table is for your information only. I t is not required for calibration.
CALIBRATION VALUES TABLE
CALIBRATION VALUES TABLECALIBRATION VALUES TABLE
Pressure Inches
of Hg
30.23768102.3-276-84101
29.92760101.300100
29.61752100.32788599
29.3374599.355817098
29.0273798.384125697
28.7473097.3112634396
28.4372296.3141343195
28.1171495.2170351994
27.8370794.2199560893
27.5269993.2229069892
27.2469292.2258778991
26.9368491.2288788090
26.6167690.2319097289
26.3466989.23496106688
26.0266188.23804116087
25.7565487.14115125486
25.4364686.14430135085
25.1263885.14747144784
24.8463184.15067154483
24.5362383.15391164382
24.2561682.15717174381
23.9460881.16047184380
23.6260080.06381194579
23.3559379.06717204778
23.0358578.07058215177
22.7657877.07401225676
22.4457076.07749236275
22.1356275.08100246974
21.8555574.08455257773
21.5454773.08815268772
21.2654071.99178279771
20.9453270.99545290970
20.6352469.99917302369
20.3551768.910293313768
Pressure
mm Hg
Pressure
kPA
Altitude
in feet
Altitude
in meters
Calibration
Value in %
YSI IncorporatedModel 9531
Page 36
1700/1725 Brannum Lane
Yellow Springs, Ohio 45387 USA
(800) 765-4974 (937) 767-7241
FAX: (937) 767-9320
Website: http://www.ysi.com
E-MAIL: environmental@ y si.com
ITEM # 059976
DRW # A59976D
October 1998
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