YSI 550 DO, Operation Manual

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YSI Incorporated YSI 550 DO Handheld Instrument 3
SECTION 1 GENERAL DESCRIPTION
The YSI 550 Handheld Dissolved Oxygen Instrument is a rugged, micro-processor based, digital
instrument with a field-replaceable YSI dissolved oxygen probe. The YSI 550 DO Instrument is
impact-resistant and waterproof.
The YSI 550 DO Instrument is designed for field use and is available with cable lengths of 12 or 25
feet. The body of the probe has been manufactured with stainless steel to add rugged durability and
sinking weight. The large Liquid Crystal Display (LCD) is easy to read and is equipped with a
back-light for use in dark or poorly lighted areas.
The YSI 550 DO Instrument’s micro-processor allows the system to be easily calibrated with the
press of a few keys. Additionally, the micro-processor performs a self-diagnostic routine each time
the instrument is turned on. The self-diagnostic routine provides you with useful information about
the function of the instrument circuitry and the quality of the readings you obtain. For a list of these
diagnostic features, see Section 6, Troubleshooting.
The system displays temperature in either
o
C or
o
F by pressing the MODE key and the down arrow
at the same time. The instrument also displays dissolved oxygen in either mg/L (milligrams per
liter) or % air saturation. The system requires only a single calibration regardless of which
dissolved oxygen display you use, however, it will calibrate in mg/L or % saturation. You can
switch back and forth from % air saturation to mg/L with a single push of the MODE key.
A detachable calibration chamber is mounted to the back of the instrument. A small sponge in the
chamber can be moistened to provide a water saturated air environment which is ideal for air
calibration. This chamber is also designed for transporting and storing the probe. When the probe is
stored in the chamber, the moist environment will prolong effective membrane performance and
probe life.
The YSI 550 DO Instrument is powered by 4 C-size alkaline batteries. A new set of alkaline
batteries will provide approximately 2000 hours of continuous operation. When batteries need to be
replaced, the LCD will display a "LO BAT" message. When the LO bat message appears, the
instrument will have approximately 50 hours of life left, depending on how much the back light is
used. If the backlight is used often, the batteries will be depleted quicker.
The YSI 550 DO Instrument case is waterproof with an IP-67 rating. The YSI 550 DO Instrument is
100% corrosion proof and can be operated in a wet environment without damage to the instrument.
1.1 KEYPAD LAYOUT
The YSI 550 DO keypad consists of six keys. See Figure 1.
There are four function keys, and up and down arrow keys. The
top left key that has a green circle and line is the ON/OFF key.
The top right key is the backlight. The bottom left is the Mode
key, and the bottom right is the Enter key.
Figure 1