The Dissolved Oxygen Meter (DOM) and Dissolved Oxygen Probe (DOP) are used to measure dissolved oxygen and temperature of naturally occurring waters, wastewaters, and certain other fluids. The meter may be used with the YSI 5239, 5905 or other 5700 series probes. Dissolved oxygen is displayed in mg/L (1 mg/L = 1 part per million) or in percent air saturation. Temperature is displayed in degrees Celsius.

Requirements: The DOM and DOP are rugged equipment designed for field use. They may also be used in a laboratory or classroom setting if desired.

Manufacturer: YSI 58 Dissolved Oxygen Meter and YSI 5239 Dissolved Oxygen Probe

Manual: YSI 58 Dissolved Oxygen Meter Manual

Suggested Courses: Environmental Science, Earth Science

Video Demonstration: (None available at this time)

Directions:

1. Install a new 5906 membrane. The DOP uses 5906 cap membranes for easy membrane replacement. If the membrane is wrinkled, dry or erratic readings are observed a new membrane may need to be installed. Membrane life depends on usage. See Figure 1.

a. Remove the plastic calibration bottle with the sponge. Unscrew and remove the probe guard. Unscrew and remove the old membrane cap from the probe.

b. Rinse the entire area of the silver anode and gold cathode with clean water (distilled or deionized) to remove dry crystals of the old electrolyte.

c. Fill the new membrane cap with 6 – 7 drops of the provided O₂ Probe KCl Solution.

d. Tap the bottom of the membrane cap gently to shake loose any air bubbles (don’t touch the membrane). Screw the membrane cap on. Then screw the probe guard on. Place the probe back in the plastic calibration bottle. Verify that the sponge in the bottle is wet.

2. Turn the instrument on. Connect the prepared probe to the PROBE receptacle and screw the retaining ring finger tight. Zero the instrument by setting the function switch to ZERO and adjust the display to read 00.0 with the O₂ Zero control knob. Wait 15 minutes for the probe to stabilize. A wait is necessary any time the meter has been OFF or the probe has been disconnected.

3. Perform an air calibration (the quickest and easiest calibration technique). Refer to the Operation Manual for Winkler Titration and Air-saturated water calibration methods.

a. Set the function switch to % mode.

b. Remove the yellow sponge in the calibration bottle and verify that it is moist. Rewet if necessary. Replace the calibration bottle over the DOP. Place the probe in a location where the temperature is stable.

c. Set the function to ZERO and readjust the display to read 00.0. Switch back to % mode.

d. Determine the local altitude or the “true” barometric pressure using the pressure/altitude chart (Appendix F, page 35) for your pressure or altitude. Unlock the O₂ Calib control locking ring and adjust the display to the calibration value indicated on the Pressure/altitude chart [from 0 to 278 feet above sea level the calibration value is 100%]. Relock the ring.

e. Daily calibration is generally appropriate.

4. Measurements should be made in moving water or the probe can be moved through the sample by hand.

a. After the probe has been calibrated, place the probe in the sample.

b. Adjust the salinity control to the salinity of the sample (not required when reading % air saturation).

c. Turn the function knob switch to the desired readout mode 0.1 mg/L, 0.01 mg/L, or % air saturation. Read the dissolved O2 value once the meter reading has stabilized.