Advanced Micro Instruments, Inc.
Page 9
Powering up the analyzer:
Press the On/Off selector button on the right side of the front panel to turn the analyzer on or off. It will show
“Init” for a few seconds, then possibly a high value, and then the reading will drop to zero and climb up to
whatever the sensor is currently measuring. When the analyzer has been stored for a while with the valve in the
“Off” position, it is normal for the unit to display between 50 and 500ppm. This is caused by diffusion of oxygen
through the O rings in the valve and sensor cap. This level of oxygen is not a problem. When low level gas flows
past the sensor the reading will drop immediately to the correct value.
If the batteries are low, the unit will flash “Bat” and “Lo” every 7 seconds or so, and otherwise show the correct
oxygen reading. You can use the analyzer if it does this, but you should recharge it as soon as you can. If the
batteries get too low for reliable operation, it will display “dEd” until the power fails so deeply that it can’t do
anything at all. If this occurs you will have to recharge it. For a complete recharge, leave it charging for at least
14 hours.
Ranging:
The electronics and software in the analyzer automatically ranges the LCD display for best resolution. The
maximum it will read is 25% oxygen, and the minimum is 0.01ppm of oxygen. The percent measurement is
provided purely for an air calibration (which is a quick and accurate way of calibrating the analyzer if you don’t
have a certified span gas).
Calibration:
When shipped, the unit and sensor have already been calibrated at the factory. However you may wish to verify
the calibration; the general procedure for doing this is to bring a suitable calibration gas into the analyzer, press
the “SPAN” button, and then adjust the reading with the UP and DOWN buttons until the analyzer agrees with
the span gas value. There is a detailed procedure describing the exact steps given later in this manual.
It is rather common to find that when you introduce span gas into the analyzer, the reading is quite different
from what you expect. This is normally caused by errors in gas handling, rather than by calibration errors. If the
gas doesn’t read close to what you expected, carefully check the calibration and troubleshooting section of the
manual - paying particular attention to the “Bleeding a regulator” section - rather than simply adjusting the span to
what may well be a completely incorrect value.
The span adjustment actually changes an internal parameter, a number called the “Span Factor” that you can
read by simply pressing the UP arrow. This number is only meaningful after a calibration when it gives you a
gauge of the remaining sensor life.
The analyzer stores the last five times it was calibrated, along with the calibration factor and the value of the
gas used. These records may be viewed with the User Interface program.
