WILDLIFE 55 User manual

IOP 011B.9
Effective Date: 1/09/2017
Replaces IOP 011B.8
Page 1 of 4
U.S. Fish and Wildlife Service
Marquette Biological Station
3090 Wright Street
Marquette, Michigan 49855
U.S.A.
and
U.S. Fish and Wildlife Service
Ludington Biological Station
5050 Commerce Drive
Ludington, Michigan 49431
U.S.A.
and
Department of Fisheries and Oceans
Sea Lamprey Control Centre
1219 Queen Street East
Sault Ste. Marie, Ontario P6A 2E5
Canada
INSTRUMENT OPERATING PROCEDURE
INSTRUMENT:
Dissolved oxygen meter
MODEL:
55
MANUFACTURER:
Yellow Springs Instrument Co., Inc.
PRECAUTIONS:
POTENTIAL INTERFERENCES
Chlorine, sulfur dioxide, nitric oxide, and nitrous oxide can affect readings by behaving like oxygen at the
membrane. Static electricity may affect readings.
SAFETY
No special precautions

IOP 011B.9
Effective Date: 1/09/2017
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PROCEDURES:
I. Meter preparation
A. At initial set-up six AA-size batteries are installed.
1. Use a screwdriver or coin to remove the thumbscrew on the bottom of the
meter.
2. Open the battery-chamber cover.
3. Install the batteries according to the label on the battery-chamber sleeves.
4. Press and release the ON/OFF button on the front of the instrument. The LCD
will come on; if not, consult the troubleshooting guide.
5. This procedure is also used when LO BAT appears on the LCD.
B. Remove the probe from the calibration chamber and add 6-8 drops of distilled water into
the sponge on the bottom of the chamber. Turn the instrument over to allow excess
water to drain.
C. Prepare the probe: this procedure is used at initial set-up and when membrane
replacement is necessary.
1. Unscrew the probe sensor guard.
2. Remove the O-ring and old membrane (if present).
3. Rinse the sensor tip and KCl reservoir with distilled water.
4. Prepare the electrolyte according to the directions on the KCl solution bottle.
5. Install the membrane (YSI Model 5775 standard membrane; 1 mil
recommended).
a. Secure a membrane between your thumb and the probe body. Add
electrolyte to the probe until a large meniscus completely covers the
gold cathode. Do not touch the center of the membrane.
b. With the thumb and forefinger of your other hand, grasp the free end of
the membrane and with a continuous motion, stretch the membrane up,
over, and down the other side of the sensor. Stretching forms the
membrane to the contour of the sensor tip.
c. Secure the end of the membrane under your forefinger while continuing
to hold the probe.
d. Roll the O-ring over the end of the probe, while being careful not to
touch the membrane surface. Leave no wrinkles in the membrane or
trapped air bubbles under the membrane. Minor wrinkles may be
removed by lightly tugging on the edges of the membrane beyond the
O-ring.
e. Trim excess membrane from the probe with scissors or a sharp
knife. Check that the stainless steel temperature sensor is not covered
by excess membrane.

IOP 011B.9
Effective Date: 1/09/2017
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f. Shake off excess KCl and rinse the stainless steel thoroughly with
distilled water to prevent corrosion. Reinstall the sensor guard. Store
the sensor in a humid environment such as the calibration chamber
between measurements and when not in use.
II. Calibration
A. Ensure that the sponge inside the instrument calibration chamber is wet. Insert the probe
into the calibration chamber.
B. Turn the instrument on by pressing the ON/OFF button on the front of the instrument.
Wait a few minutes for the dissolved oxygen and temperature readings to stabilize.
C. Use two fingers to press and release the two “up” and “down” arrow keys at the same
time.
D. The LCD will prompt you to enter the local altitude in hundreds of feet. Use the arrow
keys to increase or decrease the altitude (example: entering the number 12 indicates 1200
feet). When the proper altitude appears on the LCD, press the ENTER key once to view
the calibration value and a second time to move to the salinity compensation procedure.
E. The LCD will prompt you to enter the approximate salinity of the water you are about to
analyze. Use the arrow key to decrease the salinity compensation to 0 (fresh water
value). When 0 appears on the LCD, press the ENTER key.
F. It may be necessary to re-calibrate the instrument each time the YSI Model 55 is turned
off. Complete all calibrations at a temperature as close as possible to the sample
temperature.
III. Oxygen measurement
A Once the calibration is complete, the only keys which will remain operational are the
MODE key, the LIGHT key, and the ON/OFF key.
B. Place the probe in the water. When measuring oxygen concentration of stream water,
immerse the probe in slow moving water away from riffles or highly aerated areas.
C. Slowly move the probe to maintain movement of water across the membrane. Stream
current furnishes sufficient movement when measuring the oxygen content of stream
water.
D. Allow sufficient time for the probe to stabilize before measuring temperature and
dissolved oxygen concentration.
E. Move between the mg/L and % air saturation mode by pressing the MODE key; the
LIGHT key activates the back-light on the LCD.
F. The ON/OFF key turns the instrument off.
IV. Storage
A. Turn the ON/OFF switch to OFF.
B. Add a small quantity of deionized water to the sponge in the calibration chamber.
C. Rinse probe with deionized water.

IOP 011B.9
Effective Date: 1/09/2017
Page 4 of 4
D. Return the probe to the calibration chamber.
E. Return the meter to the storage case and secure.
MAINTENANCE:
I. Battery replacement - see section I.A.
II. Membrane replacement - see section I.C.
REFERENCE:
Operations Manual YSI Model 55 Handheld Dissolved Oxygen System
This procedure has been reviewed and approved by the undersigned representatives of the U.S.
Fish and Wildlife Service.
REVIEWED/APPROVED______________________________ DATE____________
Field Supervisor (U.S.)
Jessica M. Barber
Digitally signed by
JESSICA BARBER
Date: 2020.03.10
11:02:47 -04'00'