YSI 58 User manual

YSI 58
Dissolved Oxygen Meter
Operations
Manual

CONTENTS
SECTION 1 INTRODUCTION .......................................................................................................................1
SECTION 2 PREPARING THE METER......................................................................................................2
2.1 UNPACKING .............................................................................................................................................. 2
2.2 WARRANTY CARD.................................................................................................................................. 2
2.3 BATTERIES................................................................................................................................................. 2
SECTION 3 PREPARING THE PROBE.......................................................................................................3
3.1 CHOOSING THE CORRECT PROBE...................................................................................................... 3
3.1.1 YSI 5239 DO FIELD PROBE ........................................................................................................... 3
3.1.2 YSI 5905 BOD PROBE ..................................................................................................................... 3
3.1.3 YSI 5739 DO PROBE........................................................................................................................ 4
3.1.4 YSI 5718 DO FIELD PROBE ........................................................................................................... 4
3.1.5 YSI 5750 BOD BOTTLE PROBE .................................................................................................... 4
3.2 PROBE INSTALLATION - YSI 5739....................................................................................................... 5
3.3 CHOOSING THE CORRECT MEMBRANE........................................................................................... 5
3.3.1 MEMBRANE INSTALLATION FOR THE 5239 PROBE............................................................ 6
3.3.2 MEMBRANE INSTALLATION FOR THE 5905 PROBE............................................................ 7
3.3.3 MEMBRANE INSTALLATION FOR THE 5700-SERIES PROBES........................................... 8
SECTION 4 OPERATION..............................................................................................................................10
4.1 PRINCIPLES OF OPERATION...............................................................................................................10
4.2 TURNING THE INSTRUMENT ON......................................................................................................11
4.3 CALIBRATION.........................................................................................................................................11
4.3.1 AIR CALIBRATION.......................................................................................................................12
4.3.2 WINKLER TITRATION.................................................................................................................13
4.3.3 AIR-SATURATED WATER CALIBRATION.............................................................................13
4.3.4 CALIBRATION FREQUENCY .....................................................................................................14
4.4 MAKING MEASUREMENTS.................................................................................................................14
4.4.1 ENVIRONMENTAL CONSIDERATIONS..................................................................................14
4.4.2 MEASURING OXYGEN IN FLUIDS OTHER THAN WATER................................................ 15
4.4.3 CALIBRATING TO DISPLAY OXYGEN PARTIAL PRESSURE IN MM HG.......................15
4.5 RECORDER OUTPUT.............................................................................................................................16
SECTION 5 CARE AND MAINTENANCE................................................................................................17
5.1 THE METER CASE..................................................................................................................................17
5.2 PROBE PERFORMANCE CHECK.........................................................................................................17
5.3 PROBE PRECAUTIONS..........................................................................................................................17
5.3.1 5905 AND 5239 PROBE CARE .....................................................................................................18
5.3.2 5700-SERIES PROBE CARE..........................................................................................................19
5.4 PROBE STORAGE ...................................................................................................................................19
5.4.1 5905 AND 5239 PROBE STORAGE.............................................................................................19
5.4.2 5700 SERIES PROBE STORAGE..................................................................................................19
SECTION 6 DISCUSSION OF MEASUREMENT ERRORS..................................................................20
SECTION 7 TROUBLESHOOTING............................................................................................................21
SECTION 8 WARRANTY AND SERVICE INFORMATION................................................................23
APPENDIX A GENERAL SPECIFICATIONS.........................................................................................28
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APPENDIX B REQUIRED NOTICE.........................................................................................................30
APPENDIX C ACCESSORIES AND REPLACEMENT PARTS...........................................................31
APPENDIX D UNIT CONVERSION CHART..........................................................................................32
APPENDIX E OXYGEN SOLUBILITY TABLE.....................................................................................33
APPENDIX F CALIBRATION VALUES TABLE..................................................................................35
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SECTION 1 INTRODUCTION
The YSI 58 Dissolved Oxygen Meter is intended for field or laboratory use for dissolved oxygen and
temperature measurement and water, but is also suitable for use in certain other fluids. See Section
4.4.2, Measuring Oxygen in Fluids Other than Water. The meter may be used with the YSI 5239
probe, 5905 probe or the 5700 Series probes.
Dissolved oxygen is displayed in mg/L (1 mg/L = 1 part per million) or in percent air saturation. The
air saturation feature is discussed in detail in the next section. Display sensitivity in the mg/L mode
may be selected to read in tenths to in hundredths of a mg/L.
Temperature is displayed in °C from -5 °C to +45 °C with 0.1°C resolution. The mg/L mode is
automatically temperature compensated for changes in solubility of oxygen in water and for
permeability of the probe membrane. A salinity compensation control allows direct determination for
mg/L of dissolved oxygen in oceanic or estuarine waters.
The probes use Clark-type membrane covered polargraphic sensors with built-in thermistors for
temperature measurement and compensation. A thin, permeable membrane stretched over the sensor
isolates the sensor elements from the environment, but allows oxygen and certain other gases to enter.
When a polarizing voltage is applied across the sensor, oxygen that has passed through the membrane
reacts at the cathode, causing a current to flow.
The membrane passes oxygen at a rate proportional to the pressure difference across it. Since oxygen
is rapidly consumed at the cathode, it can be assumed that the oxygen pressure inside the membrane is
effectively zero. Hence, the force causing the oxygen to diffuse 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.
PERCENT SATURATION
The percent saturation feature of this instrument allows quick determination of the degree of air
saturation occurring in fresh or saline water. This feature also allows measurement in fluids of
unknown oxygen solubility.
The percent saturation displayed in this mode is the saturation that would occur if the sample were
saturated with air under a normal barometric pressure of 1013 millibars (760 mm Hg or 29.92 inches
Hg). Results reported from such measurements should be noted as air saturation, corrected to standard
pressure.
This feature also makes possible a simple and quick calibration procedure that eliminates the need to
determine exact probe temperature or to calculate the barometric pressure effect on the calibration
value.

SECTION 2 PREPARING THE METER
2.1 UNPACKING
When you unpack your new YSI 58 Dissolved Oxygen and Temperature System for the first time,
compare the packing list with the contents of the shipping box. If there is anything missing or
damaged, contact your YSI dealer from whom you purchased the YSI 58 or YSI Customer Service at
800-765-4974 or 937-767-7241.
2.2 WARRANTY CARD
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.
2.3 BATTERIES
Batteries provide complete portability; a battery eliminator feature bypasses the instrument batteries
for extended line-powered use (not including stirrer). Instrument batteries are carried internally in one
holder while a second holder allows internal installation of batteries for powering a submersible stirrer
for use in the field.
Instrument batteries are in the upper holder. Four D-size carbon-zinc batteries are used. The LOBAT
warning shows on the display when about 50 hours of use remain. This warning reminds the operator
to change batteries at their earliest convenience. Batteries may be removed when the instrument will
be used on a long-term basis for laboratory measurement powered by the YSI 5401 or 5402 battery
eliminator.
Stirrer batteries fit in the lower battery holder. Four D-size carbon-zinc batteries are used. When
about five hours or less of battery life remains, the LOBAT warning will show on the display when
the STIRRER control is held at the spring-loaded BATT CHK position. Instrument must be turned
on. Batteries are needed only when the YSI 5795A Submersible Stirrer will be used.
YSI 5401 (115 VAC) AND 5402 (230 VAC) BATTERY ELIMINATORS
For exclusive or long-term laboratory use, the 5401 or 5402 Battery Eliminator may power the YSI
58. When the battery eliminator is in use, batteries may be removed from the instrument battery
compartment (upper compartment).
Note: The battery eliminator does not power the 5795A Field Stirrer, which operates only when
there are batteries in the stirrer battery compartment (lower compartment).
YSI Incorporated YSI 58 DO Meter 2

SECTION 3 PREPARING THE PROBE
3.1 CHOOSING THE CORRECT PROBE
Five different YSI oxygen probes may be used with the YSI 58 Meter.
¾YSI 5239 is designed for field use with cable lengths of 10, 25 or 50 foot.
¾YSI 5905 is a self-stirring BOD bottle probe.
¾YSI 5739 is designed for field use and may be used with or without a stirrer. A 5740 probe cable
or 5795A stirring cable is required for use with the 5739 probe. YSI 5795A has a dual-purpose
cable to which both stirrer and probe are connected.
¾YSI 5750 is a BOD bottle probe with no stirrer.
¾YSI 5718 is designed for field use with no pressure compensation and has a permanently attached
cable.
3.1.1 YSI 5239 DO FIELD PROBE
The YSI YSI 5239 probe is used for measuring dissolved oxygen in the field. It features cap
membranes for easy membrane replacement (YSI 5906 membrane caps). The probe is rugged, with
the DO and temperature sensors enclosed in a heavy-duty probe guard. A 10, 25 or 50 foot cable is
directly connected to the probe body making it waterproof. A 5-pin MS connector at the end of the
cable makes the 5239 fully compatible with all YSI 50 series DO meters retaining the accuracy of the
system. The 5239 has been optimized for YSI meters which have a microprocessor for sampling and
processing data, such as YSIs 50B and 52.
NOTE: The 5239 probe is shipped dry. A shipping membrane was installed to protect the electrodes.
A new membrane cap must be installed before first use.
3.1.2 YSI 5905 BOD PROBE
The YSI 5905 BOD (Biochemical Oxygen Demand) probe is used for measuring dissolved oxygen in
all popular size BOD bottles. This probe features a self-stirring probe and an easily replaced
membrane cap and a refurbishable electrode system.
IMPORTANT: Intended Use
The 5905 probe is intended for laboratory use, not field use. It is not waterproof and should never be
immersed past the taper on the stem of the probe.
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The 5905 probe is designed for use with all YSI dissolved oxygen meters, except for the YSI 55, 85
or YSI 95. The 5905 probe comes in several versions, designed to fit different bottle sizes.
5905
5° taper per side to fit U.S. Standard BOD
bottles.
5905 - J
Includes an adapter to fit 5° taper per side smaller bottles with built - in overflow funnels.
5905 - K
Includes a s 19 funnel.
5905 - L
Includes a s 24 funnel.
5905 - W
6″long probe for use with wine bottles.
3.1.3 YSI 5739 DO PROBE
For user convenience, the 5739 probe is equipped with a disconnecting cable to facilitate changing
cable lengths and replacing damaged cables or probes. The probe and cable assembly is held together
with a threaded retaining nut. The connection is not designed for casual disconnection and should
only be disconnected when necessary. For sample stirring with the 5739 probe, the 5795A
Submersible Stirrer has a dual-purpose cable to which both stirrer and probe are connected.
YSI 5795A SUBMERSIBLE STIRRER
The YSI 5795A Stirrer, which can only be used
with the 5739 probe, features a single cable for
both probe and stirrer to permit convenient
manipulation and storage.
Figure 1
When a stirrer and probe are assembled, the
stirrer agitates the sample directly in front of the
sensor by means of a rotating eccentric weight
that causes the spring-mounted, sealed motor
housing to vibrate. An impeller on the end of
the motor housing flushes the fluid being
assayed across the sensor surface.
3.1.4 YSI 5718 DO FIELD PROBE
The YSI 5718 field probe has a permanently attached cable and no pressure compensation.
3.1.5 YSI 5750 BOD BOTTLE PROBE
The YSI 5750 probe is similar in design to the 5739, but has a tapered body designed to fit standard
US BOD bottles. It does not have a stirrer or cap membranes. Agitation of the sample must be
provided by other means, such as a magnetic stirrer.
YSI Incorporated YSI 58 DO Meter 4

Four D-size carbon-zinc batteries that are housed in the lower battery compartment of the YSI 58
power the stirrer. When the stirrer will not be used for an extended period, these batteries should be
removed from the instrument.
3.2 PROBE INSTALLATION - YSI 5739
To disconnect the cable, unscrew the retaining nut and slide it down the cable to expose the
connector. Pull gently on the cable and connector until the connector comes away from the probe
body.
To reassemble, inspect the connector and O-Ring for cleanliness. If the O-ring is frayed or damaged,
remove it by squeezing it in the groove causing it to bulge, then roll it out of the groove and off of the
connector. A replacement O-ring is supplied with the cable.
Push the connector into the probe body, rotating it until the two halves match up. A VERY LIGHT
coating of silicone grease on the O-Ring will make reassembly easier.
CAUTION: DO NOT apply more than a light coating of grease, as it will attract dirt and particles that
may compromise the seal of the O-ring.
Air trapped between the connector halves that may cause them to spring apart slightly is normal.
Screw on the retaining nut, HAND TIGHTEN ONLY!
Note: If erratic readings are experienced, disconnect the cable and inspect for the presence of water. If
water is present, dry out and reconnect, replacing the O-Ring.
Pressure Compensation
The vent on the side of the probe is part of a unique pressure compensating system that helps assure
accurate readings at great depths of water. Pressure compensation is effective to 0.5% of reading with
pressures to 100psi (230 feet water). The quantity of air bubbles trapped under the membrane
determines how serious the pressure error will be, which is why proper preparation of the probe is
essential. See Section 4, Operation. The system is designed to accommodate a small amount of
trapped air and still function properly, but the amount should be kept to a minimum.
The compensating system normally does not require servicing and should not be taken apart.
However, if electrolyte is leaking through the diaphragm or if there is an obvious puncture, the
diaphragm must be replaced. A spare is supplied with the probe. Using a coin, unscrew the retaining
plug and remove the washer and diaphragm, flush any salt crystals from the reservoir, install the new
diaphragm (ridged side in), replace the washer and screw in the retaining plug.
3.3 CHOOSING THE CORRECT MEMBRANE
An extremely thin membrane increases O2permeability and probe signal current, and hastens a
probe’s response; but it achieves this at the cost of ruggedness. The membrane normally used with the
YSI 58’s probes is the 1 ml (.001”) membrane. This 1 ml membrane represents a compromise
between quickness of response, and membrane strength and integrity.
For special circumstances, a 0.5 ml (.0005”) membrane is available. This half-thickness membrane
hastens response at low temperatures and helps suppress background current at very low dissolved
YSI Incorporated YSI 58 DO Meter 5

oxygen levels. When data is routinely collected with sample temperatures below 15°C and at DO
levels below 20% air saturation, the low signal current resulting from the use if the standard
membranes tends to magnify the probe’s inherent constant background signal. Using the high
sensitivity membranes in this situation will decrease the percent error due to the probe’s background
current.
For long-term monitoring situations only, a half-sensitivity, double-thickness 2 ml (.002”) membrane
is available. Order the YSI Item # 5685 2 ml membrane, which includes membranes and electrolyte
for the 5718 and 5739 probes.
A selector switch inside the YSI 58 modifies the circuit for the membrane in use. This switch must be
set to the position corresponding to the membrane in use. Facing the back of the instrument, with the
back cover removed, the switch will be found on the top, right corner of the main PC board. Its
positions are labeled .5, 1 and 2 MIL. Also, See Section 4.4.2, Oxygen Measurements in Fluids
Other Than Water, for use of this switch in special measurement circumstances.
Membrane life depends on usage. However, if the electrolyte is allowed to evaporate and an excessive
amount of bubbles form under the membrane, or the membrane becomes damaged, thoroughly flush
the reservoir with electrolyte and install a new membrane.
If erratic readings are observed or calibration is stable, you need to replace the membrane.
The gold cathode should always be bright and untarnished. If it is tarnished, which can result from
contact with certain gases, or plated with silver, which can result from extended use with a loose or
wrinkled membrane, return it to YSI for service. You can also clean the gold cathode with the YSI
5680 Probe Reconditioning Kit. Never use chemicals or any abrasive other that what is supplied with
the kit. See Section 8 for contact information.
3.3.1 MEMBRANE INSTALLATION FOR THE 5239 PROBE
NOTE: The 5239 probe is shipped dry. A shipping membrane was installed to protect the electrodes.
A new membrane cap must be installed before first use.
Follow the steps below to install a membrane cap:
1. Unscrew and remove the probe guard. See figure 2.
2. Unscrew the old membrane cap and remove it from the probe.
3. Thoroughly rinse the entire area of the silver anode, gold cathode and threads with clean
water (distilled or deionized) to remove any dry crystals of the old electrolyte.
4. Hold the membrane cap and fill it with 6 to 7 drops of YSI standard electrolyte (KCl probe
solution) provided.
5. Tap the bottom of the membrane cap with your finger a few times (don’t touch the
membrane) to shake loose any trapped air bubbles.
6. Screw the membrane cap onto the probe moderately tight. A small amount of electrolyte
should overflow.
7. Rinse off the excess electrolyte with clean water.
8. Screw the probe guard onto the probe body.
9. Place the probe in the calibration bottle provided. Verify that sponge in the bottle is wet.
YSI Incorporated YSI 58 DO Meter 6