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Instructions on Using a Milwaukee Dissolved Oxygen Meter

As their name suggests, dissolved oxygen meters measure the amount of gaseous oxygen dissolved in an aqueous solution. They are important tools for determining the usability of water sources in sewage treatment, fish farming and other applications. The Milwaukee company is a popular supplier of oxygen meters, but no matter where your meter comes from, it is important to follow proper procedure when operating these sophisticated, delicate machines.

Things You'll Need

Milwaukee dissolved oxygen meter set with probe, display meter and probe membrane
Milwaukee electrolyte solution for dissolved oxygen probes
Milwaukee zero oxygen solution
Water sample moving at least 0.3 meters per second

Instructions

Preparation
- 1
  Soak the oxygen meter's sensor, located on the tip of its probe, in electrolyte solution for 5 minutes.
- 2
  Rinse the probe's membrane with electrolyte solution while the sensor is soaking, shaking it gently to fully clean.
- 3
  Fill the membrane with fresh electrolyte solution.
- 4
  Disengage air bubbles from the membrane by tapping it gently on the side with a pencil or other small rod. Avoid tapping the bottom of the membrane.
- 5
  Insert the O-ring inside the membrane cap and screw the cap onto the probe with the sensor pointing down.
- 6
  Look over the probe to ensure air bubbles are not trapped between the membrane and the sensor.
- 7
  Connect the assembled probe to the oxygen meter, and press the meter's "on/off" switch to turn it on.
- 8
  Wait at least 15 minutes for the oxygen meter to automatically polarize the probe.
Zero Calibration
- 9
  Remove the protective cap from the polarized probe.
- 10
  Submerge the probe in zero oxygen solution
- 11
  Stir the probe gently in the zero oxygen solution for 2 to 3 minutes.
- 12
  Wait for the probe's display reading to stabilize at its lowest level.
- 13
  Adjust the zero dissolved oxygen trimmer to 0.0. The trimmer is located on the meter's front panel.
Slope Calibration
- 14
  Rinse the probe thoroughly once it is zero-calibrated to remove all zero oxygen solution.
- 15
  Dry the probe and suspend it over a container of water while it dries, allowing it to slope-calibrate over water-saturated air.
- 16
  Press and hold the CAL button. While holding CAL adjust the front panel's slope trimmer until the display reads 100.0 percent.
- 17
  Release the CAL button, and the meter should display an oxygen value in parts-per-million.
Using the Meter
- 18
  Submerge the oxygen meter's probe in the water sample.
- 19
  Wait for the oxygen reading to stabilize then move the probe around a bit to ensure the water is moving at a minimum of 0.3 meters-per-second. If the reading remains constant the water motion is sufficient. If the reading increases the movement is insufficient.
- 20
  Wait at least a few minutes for the temperature of the submerged probe to match the temperature of the water before recording the oxygen level.

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