Thermo Scientific AquaSensors
™
AnalogPlus
™
Dissolved Oxygen Sensor (ppm) User Guide
7
2.2.
Sensor Care and Start-up
Working with the Protective Cap
The sensor is shipped with a protective cap on the sensor head to keep the membrane wet and to protect the
membrane from damage. The cap should remain on the sensor head until the sensor is installed in liquid
process. It is important to note that the cap should be pulled straight off by inserting a fingernail between the
cap and the sensor body and walking the cap down until it comes off. Be careful not to touch the membrane.
Working with the Membrane Cap
The membrane cap is screwed on and care should be taken not to unscrew it. The cap contains dissolved
oxygen electrolyte that will spill out if the cap is removed.
Power the Sensor Prior to Calibration
The sensor has been charged and tested prior to shipment. After installation, leave the sensor powered for at
least 4 hours in the process prior to calibration. The AV88 analyzer supports both 1-point sample calibration
and air calibration.
The 1-point sample calibration should be done with a measured DO reading that is as high up the scale as
possible, ideally 8 or 9 ppm. With this calibration the current sensor reading can be set to a known value.
With the Air calibration, the sensor is held in air and with atmospheric pressure correctly configured, will
calibrate to a calculated value of oxygen in the air. If there is a large temperature difference between the
water and the air it may be necessary to wait for up to 5 minutes before the temperature of the sensor body
comes to a new steady state.
Temperature can also be calibrated with a sample calibration and it may be advantageous to calibrate the
temperature of the sensor prior to calibration of dissolved oxygen since the D.O. reading is compensated by
temperature.
Take care to protect the sensor membrane from impact and be sure to keep the membrane cap tight.
Membrane material covers
electrodes and should be
protected from impact.
Membrane Cap tightens when turning it
clockwise. Keep it tight.
