MANTAWater Quality Multi-probe

Eureka Environmental Engineering

Optical Dissolved Oxygen Sensor Calibration

Overview:The Manta Water Quality Multi-probe (Manta) can monitor multiple parameters consecutively in the field. The various sensors are factory installed and come “ready to use” however, calibration of the device to the local environmental conditions (barometric pressure, altitude) is very important for accurate data collection. This document will provide a quick overview of how to calibrate the Manta optical oxygen sensor using a laptop computer. It does not cover software installation or Amphibian operations. Optical Dissolved Oxygen The optical dissolved oxygen sensor can be calibrated either with 100% water saturated air, or the recommended method with a zero oxygen sodium sulfite based standard. The advantage to the zero oxygen solution is that peak signal output from the sensor is actually at zero mg/l. The sensor is very linear, and may require less frequent calibration than Clark cell dissolved oxygen sensor. Clean sensor before calibration and follow the steps on the Manta Manager or Amphibian software to calibrate.

Equipment Overview:The equipment required for calibration of the Manta through a PC is: 1) Manta probe with cable, 2) calibration cup, 3) USB cable, and 4) PC with Manta Manager software and USB drivers installed. The blue USB cable provided is specifically designed for the Manta and is not to be used for any other device. The cable attaches to a USB port on the computer and to the prong end of the Manta cable. Power for the Manta is provided via the USB cable so it is recommended to have the laptop plugged into a power outlet. It is also recommended to use the same USB port each time.

Procedure:Clean the Optical Oxygen sensing surface (red material, 1cm diameter) with a non-abrasive warm soap solution and a soft cloth. Do not use any abrasive solutions, acetone, kerosene, or industrial cleansers.

Connect the Manta to the computer. Wait 15 seconds after the green light on the Manta begins blinking. Start the Manta Manager software. The software takes a few moments to find the Manta (searches the last port used therefore it is recommended to use the same port each time). When the Manta is found, the computer display shows a continuous reading:

On the left side are buttons for options. Select [ Calibration].

The calibration screen will show up and display all sensors on the Manta, last calibration data, and the settings. From this screen, the barometric pressure, internal clock, and altitude can be adjusted.Select one of the oxygen sensor calibration buttons.

Depending on which type of oxygen reading (mg/L or %Sat), the displays are slightly different. Note: %Sat allows barometric pressure and calibration solution to be adjusted (right display).

The optical sensor can be calibrated at both 0% saturation and 100% saturation and performing both methods is recommended. 0% Saturation Method: replace the storage cup on the probe end with the calibration cup and fill with sodium sulfide zero DO solution, enter ‘0’ on the calibration solution box. Wait for temperature to balance and press ‘calibrate’ or ‘start’.100% Saturation Method: Shake a jar of water vigorsly for 1 minute, let settle for 5 to remove the air bubbles. Place shaken water into the calibration cup. Enter ‘100’ into the calibration solution box. Press [Start] or [Calibrate] depending on procedure used.

This is all one needs to do to calibrate the Manta Optical Oxygen Sensor. Record of the calibration can be viewed on the first entry screen on the Manta Manager program. To disconnect the Manta, just unplug it from the computer (a USB reject may need to be performed on the computer first).

Some information and pictures in this document were obtained from the Eureka Manta

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