YSI Model 5239 Dissolved Oxygen Probe Instruction Manual
Table of Contents INTRODUCTION ........................................................................ 1 PROBE CONFIGURATION ....................................................... 1 SYSTEM SPECIFICATIONS ...................................................... 1 TEMPERATURE COMPENSATION ........................................... 2 PROBE OPERATION ................................................................. 2 MEMBRANE INSTALLATION .................................................. 2 CALIBRATION .......
WARRANTY AND REPAIR ...................................................... 14 CLEANING INSTRUCTIONS .................................................. 16 PACKING INSTRUCTIONS.....................................................
INTRODUCTION The YSI Model 5239 probe is used for measuring dissolved oxygen in the field. It is the first field probe that 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.
• DO range: 0 to 200 % air saturation or 0 to 20 mg/L. • DO accuracy: ±2 % or ±0.2 mg/L whichever is greater. • DO response time: 30 sec for 95% of change at 25°C. TEMPERATURE COMPENSATION Temperature compensation of DO readings is provided by the YSI DO meter. For best results, calibrate within ±5° C of the sample temperature. PROBE OPERATION 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.
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. Fill membrane cap with 6-7 drops of KCl solution.
titration. Choose the one which best fits your application. Calibration in air is the simplest and most accurate method of calibration. • For air calibration, place the probe in air at 100% relative humidity. To achieve this, place the probe in the plastic calibration bottle (provided) with a wet sponge or paper towel in the bottom. • For air-saturated water calibration, air-saturate a volume of water (300 to 500 ml) by aerating for at least 15 minutes at a relatively constant temperature.
3. Check the membrane to make sure there are no water beads attached to it. Wipe to remove the water beads with a soft tissue if necessary. NOTE: Make sure that the probe has been in the calibration bottle for more than 2 minutes before calibrating so that both the thermistor and DO sensor are at the same temperature. 4. Calibrate the system according to the instructions in the operations manual for the particular YSI 50 series meter you are using.
INTERFERENCES Hydrogen sulfide, sulfur dioxide, halogens, carbon monoxide, chlorine, nitric oxide, and nitrous oxide can cause the probe to give erroneous readings. If you suspect erroneous readings, it may be necessary to determine if these are the cause. ACIDS Avoid any environment that contains substances such as concentrated acids, caustics, and strong solvents that may attack the probe.
PRINCIPLES OF OPERATION THE CLARK OXYGEN SENSOR The 5239 probe is a Clark type polarographic (voltammetric) dissolved oxygen sensor. The sensor is made of a silver anode and a gold cathode (see Figure 2), and is separated from the measured medium by a semi-permeable Teflon membrane. The temperature sensing element (thermistor assembly) is mounted next to the oxygen sensor vertically, providing temperature readings for the DO system.
anode/reference electrode which 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: O2 + 2H2O + 4e ==> 4OH Anode reaction: Ag + Cl ==> AgCl - THE DO READINGS FROM THE CATHODE REDUCTION The oxygen reduction current is sampled and processed, by the meter, and displayed as either %-air saturation or mg/L.
(an insoluble solid and poor conductor of electricity) accumulates at the anode, it begins to block the passage of current in the electrolytic cell. The silver anode must be cleaned periodically to prevent this thick layer of silver chloride from reducing the sensitivity of the sensor. THE FUNCTION OF THE ELECTROLYTE There are two main functions for the electrolyte: - 1. Supply the chloride (Cl ) to the anode/reference electrode for the counter reaction of the oxygen reduction at the cathode. 2.
MAINTENANCE AND TROUBLESHOOTING MEMBRANE CAP LIFE 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. Keep the probe in a moist atmosphere as much as possible to avoid drying out the electrolyte. Erratic readings will result from loose, wrinkled or fouled membranes, or from bubbles larger than 1/8” in the electrolyte solution. The following things are likely to cause short membrane life: 1.
ELECTRODE CLEANING It is always a good practice to keep the probe in good operating condition. 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.
Stick the disc to the sanding tool, then wet sand the gold with a twisting motion about 3 times or until all silver deposits are removed and the gold appears to have a matte finish. If the cathode remains tarnished, return the probe for service. Wipe the gold cathode thoroughly with a wet paper towel before putting on a new membrane cap. TROUBLE SHOOTING GUIDE Below is a quick reference of symptoms with steps to follow to cure these symptoms.
Symptoms Does not hold calibration Actions • Allow sufficient time for temperature and oxygen stabilization before calibration • Check for water droplets on membrane • Check membrane for a pinhole or split • Change membrane • Clean probe (see instructions under Electrode Cleaning) Unstable readings • Check membrane for a pinhole or split • Allow 60 sec.
WARRANTY AND REPAIR YSI Model 5239 Dissolved Oxygen Probes are warranted for one year from date of purchase by the end user against defects in materials and workmanship. Within the warranty period, YSI will repair or replace, at its sole discretion, free of charge, any product that YSI determines to be covered by this warranty. To exercise this warranty, write or call your local YSI representative, or contact YSI Customer Service in Yellow Springs, Ohio.
YSI Authorized Service Centers For the nearest authroized service center contact: YSI Technical Support • 1725 Brannum Lane • Yellow Springs, OH • 45387 Phone: +1 937 767-7241 • Fax: 937 767-9353 • environmental@ysi.com • www.ysi.
CLEANING 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.
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 1. Clean and decontaminate items to insure the safety of the handler. 2. Complete and include the Cleaning Certificate. 3.
Cleaning Certificate Organization ________________________________ Department _________________________________ Address ___________________________________ City _______________ State ______ Zip ________ Country __________________ Model No.
1725 Brannum Lane Yellow Springs, Ohio 45387 USA 937 767-7241 • 800 765-4974 Fax 937 767-9353 Environmental@YSI.com • www.YSI.
