How The Reference Check Function Works; How The Auto-Test Method Works - Ametek mocon AQUATRAN 3/40 Operator's Manual

AQUATRAN Model 3/40 Operator's Manual

How the Reference Check Function Works

The instrument contains a dedicated "Reference" cell that is used to track instrument performance over
time. The Permeable barrier material used in the Reference Cell is located in the Test Chamber. The
Reference Cell barrier is therefore exposed to the same test conditions as the samples mounted in the Test
Cells. The Reference Check function is used to measure the transmission rate of the Reference Cell.
When the "Reference Check" function is enabled a "Reference Test" will be performed whenever a test is
started on any Test Cell and all of the Test Cells were previously idle. The Reference Check function is an
Instrument Level test parameter located on the "Instrument" test method screens.
The Reference cell will be examined during the Test Phase after the Purge and Conditioning states (when
present) have completed. The Examination Time of the Reference cell is not user accessible.
After the Reference Test has completed the measured transmission rate is normalized to 23 °C. The
transmission rate of the barrier material used in the Reference Cell is not significantly affected by changes
in Chamber RH.
The Reference cell data is accessed using the Cell Status screen. The result for each Reference Cell
examination is shown in g/(pkg • day). A maximum of 365 days of data will be retained and displayed. The
graph contains limit bars at 5% and 10% from the stated value of the Reference Cell.
The Reference cell data can be printed and exported using the controls on the Reference Cell Status
screen.

How the Auto-Test Method Works

The Auto-Test Method utilizes an internal rule-set to dynamically optimize how a permeation test is
performed. The Auto-Test Method also utilizes an advanced dynamic convergence algorithm to determine
when the sample has reached equilibrium. The Equilibrium Determination is used to advance the test to the
next phase or terminate the test as required by the criteria in the rule-set.
The measured transmission rate and internal rule-set are used to dynamically optimize the Cell Examination
time, the ReZero Frequency, the ReZero Examination time and the Individual Zero State.
The Convergence algorithm makes an Equilibrium Determination based on the absolute-magnitude-of or
the magnitude-of-change-in the transmission rate. If the absolute magnitude of the transmission rate is less
than the noise floor of the instrument, the sample is declared to be at equilibrium. Above the noise floor the
acquired Cell Examination data is used to calculate two variables. These variables are calculated using data
sets representing different time frames. These variables represent the "Current" transmission rate and the
MOCON, Inc. Revision D
Theory of Operation
D-5