AMI Analyzer Manual
Model 111/111P Oxygen Analyzer
3
Data logging:
The unit contains a real-time clock and 32K of non-volatile memory that provide a data logging function to
be accessed by the AMI User Interface Program. It will automatically log readings and the time and date at
intervals for subsequent downloading into a computer.
It records the average reading over a user-selectable period (in minutes), and after every 32 readings it
records the time and date so that the user may reconstruct the data accurately. If logging is turned off, and
then restarted, it will continue logging where it left off (starting with a new time and date stamp) – it won’t
overwrite the earlier data until it reaches the end of its memory.
Using the User Interface program supplied by AMI, the data may be downloaded into a “CSV” file for
manipulation in Excel™ or similar spreadsheet programs, and the logging can be restarted at the beginning
again. The internal time and clock may also be set, as well as a label to distinguish data from this analyzer
from others.
As an example, if the time interval is set for 1 minute, the unit will average the readings for one minute and
then store the average. Every 32 minutes it will also store the current date and time. It will continue doing
this for about 20,000 data points, i.e. about two weeks, assuming it is left plugged in to its charger! After
that time it will start writing over its earliest data.
Sample conditioning:
The model 111 is intended to use a positive pressure sample. The sample should be free of liquids, and
dust. It must be free of combustible material, since the sensor will oxidize anything combustible, reducing
the oxygen reading by the amount it took to burn up the contaminant. It is intended to operate with
nitrogen as the background gas – high concentrations of other gases may be problematical, mostly because
any significant change in thermal conductivity will either overheat or cool off the sensor. Generally
speaking, up to 10% of any non-flammable gas is not a problem, but higher concentrations (other than
nitrogen) may be. Please contact the factory for details if this should apply to you.
The analyzer does not respond to barometric pressure changes, unlike conventional oxygen analyzers.
Optional versions are available that can measure oxygen up to 50% or 95%.
The model 111P is equipped with a long-life pump, capable of drawing a sample through the sensor from an
ambient pressure source, or vacuums down to 15”Hg. It will also operate at inlet pressures up to 10psig.
The pump does draw more current than the rest of the analyzer, so the battery life is considerably shorter if
you run the pump all the time; however like the standard unit it will operate indefinitely if plugged into its
charger.
Using the AMI user interface program, the unit can be programmed to switch off the pump after a few
minutes of operation, though by default it will run continuously. The LED on the front panel will change
from green to blue when the pump is in use. If the batteries are low, the pump will only run for five
seconds. Sometimes when the batteries are getting low, the increased current draw of the pump will
