YSI 550A Dissolved Oxygen Instrument Operations Manual
CONTENTS CONTENTS .................................................................................................................................................iii GENERAL DESCRIPTION ...................................................................................................................... 1 WARRANTY................................................................................................................................................ 2 FEATURES OF THE YSI 550A.........................
GENERAL DESCRIPTION The YSI 550A Handheld Dissolved Oxygen Instrument is a rugged, microprocessor based, digital instrument with a field-replaceable YSI dissolved oxygen probe. The YSI 550A DO Instrument is impact-resistant and waterproof. The YSI 550A DO Instrument is designed for field use and is available with cable lengths of 12, 25, 50, or 100 feet (3.5, 7.5, 15, 30.5 meters). The body of the probe has been manufactured with stainless steel to add rugged durability and sinking weight.
WARRANTY REGISTRATION Please complete the Product Registration on the YSI website at www.ysi.com. If you are not online, you may complete the Warranty Card included with your instrument and return it to YSI Incorporated. Your purchase of this quality instrument will then be recorded in YSI’s customer database. Once your purchase is recorded, you will receive prompt, efficient service in the event any part of your YSI 550A DO Instrument should ever need repair.
FEATURES OF THE YSI 550A KEYPAD Powers the unit on or off. The instrument will activate all segments of the display for a few seconds, and then will show a self-test procedure for several more seconds. During this power on self-test sequence, it is normal to error messages appear and disappear. If the instrument were to detect a problem, a continuous error message would be displayed. Turns the display backlight on or off. The light will turn off automatically after two minutes of non-use.
Caution: 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 manufacturer's warranty. CALIBRATION/STORAGE CHAMBER The YSI 550A DO Instrument has a convenient calibration/storage chamber that can be attached to the instrument’s back. The calibration chamber can be used from either side of the instrument, by moving the rubber stopper to either end.
5. Press the two velcro strips back together. PRINCIPLES OF OPERATION The sensor consists of a silver body as the anode and a circular gold cathode embedded in the end. In operation, this end of the sensor is filled with a solution of electrolyte containing a small amount of surfactant to improve wetting action. A thin semi-permeable membrane, stretched over the sensor, isolates the electrodes from the environment, while allowing gases to enter.
DISSOLVED OXYGEN CALIBRATION Dissolved oxygen calibration must be done in an environment with known oxygen content. The YSI 550A DO Instrument can be calibrated in either mg/L or % saturation. Sections below include instructions on how to calibrate in either mode. BEFORE YOU CALIBRATE To accurately calibrate the YSI 550A, you will need to know the following information: • The approximate salinity of the water you will be analyzing. Fresh water has a salinity of approximately zero.
6. CAL will now display in the lower left corner of the screen, the calibration value in the lower right corner and the current DO reading (before calibration) will be the main display. Once the current DO reading is stable, press the ENTER button. 7. The LCD will prompt you to enter the approximate salinity of the water you are about to analyze. You can enter any number from 0 to 70 parts per thousand (PPT) of salinity. Use the arrow keys to increase or decrease the salinity setting.
PROBE OPERATION NOTE: The YSI 550A DO Instrument should not be used in a purpose other than that specified by YSI Incorporated. See Warranty for details. STIRRING It is important to recognize that a very small amount of oxygen dissolved in the sample is consumed during probe operation. It is therefore essential that the sample be continuously stirred at the sensor tip. If stagnation occurs, measurements will appear artificially low.
PROBE ELECTRODE MAINTENANCE SILVER ANODE After extended use, a thick layer of 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 or mechanical: • Chemical cleaning: Remove the membrane cap and rinse the electrodes deionized or distilled water.
1. 2. 3. 4. 5. 6. 7. Remove probe guard. IMPORTANT: Thoroughly dry the PROBE sensor so that no water enters the GUARD probe port when the sensor is removed. DO Insert the long end of the hex key SENSOR SET wrench into the small hole in the side SCREW of the DO sensor. Turn the wrench CABLE counter clockwise until the sensor is HEX KEY released. WRENCH Pull the DO sensor out of the probe. The DO sensor is keyed, or has a flat side, so that it can not be removed or inserted improperly.
SPECIFICATIONS Display Resolution Range Accuracy Dissolved O2 mg/L 0.01 mg/L or 0.1 mg/L, user selectable 0 to 20 mg/L Dissolved O2 % 0.1% or 1%, user selectable Temperature ºC Temperature ºF 0.1 ºC 0.1 ºF ± 0.3 mg/L or ± 2% of reading, whichever is greater ± 6% of reading ± 2% air sat or ± 2% of reading, whichever is greater ± 6% of reading ± 0.3 ºC ± 0.
TROUBLESHOOTING NOTE: An error displayed briefly during the first few seconds after turning the instrument on does NOT indicate a problem. SYMPTOM POSSIBLE SOLUTION 1. Instrument will not turn on, LCD displays "LO BAT", or Main display flashes “OFF” A. Low battery voltage, replace batteries B. Batteries installed incorrectly, check battery polarity C. Return system for service 2. Instrument will not calibrate. A. Replace membrane and electrolyte B. Clean probe electrodes C.
SYMPTOM 8. Main display reads “Err” and Secondary display reads “RO”, “RA”, or “AdC”. 9. Main display reads “Err” or burn” and Secondary display reads “EEP” POSSIBLE SOLUTION A. Return system for service A. Return system for service CONTACT INFORMATION YSI offers a wide range of customer assistance and technical support functions to ensure that you have the information required to use our products. Contact YSI Environmental if you need assistance or have questions regarding any YSI Environmental Product.
REQUIRED NOTICE 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.
