Troubleshooting
OX-TRAN Model 2/22 Operator’s Manual
8-2
Revision R
MOCON, Inc.
Symptom
:
Abrupt changes in display readings or long-term cyclic oscillations.
Comment
:
Unwanted data fluctuations observed during a test cycle may be caused by abrupt
changes in the carrier gas flow rate. Such a transient symptom can be produced by a
temporary restriction in any gas line, or gas usage by another system.
Regular, cyclic data fluctuations may also be observed in connection with ambient
package tests where the test packages are exposed to ambient temperature
fluctuations caused by frequent on/off heater and air conditioner cycles.
Solution:
An Environmental Chamber (MOCON P/N 001-001) can be used when testing
packages to reduce or eliminate this problem.
When testing packages, this effect can also be minimized by placing a loose-fitting
plastic bag over the specimen, or by placing the specimen in an insulated box.
Recovering from a Sensor Over-Range Condition
A severe over range condition will terminate the test sequence on both cells.
If you see a red Cell Status indicator (on the front of the instrument), the test has failed due to a gas sensor
over-range condition. In addition to the red Cell Status indicator, an error indicator may be displayed on the
Home screen.
Examine the data on the Cell Status screen to determine the cause of the over-range condition. The Cell (or
Cells) that caused the over-range will be “Failed”. If the ReZero Cell failed due to an over-range condition all
active tests will be failed.
Possible causes may be:
•
The sample has a high transmission rate. To correct the problem testing can be done using a
lower oxygen concentration test gas or a foil mask.
•
The sample has pinholes, cracks or a poor-sealing surface.
•
The cell is installed and clamped but no barrier is present.
•
The o-ring seals on the top of the Test Cell are missing or damaged.
After correcting the cause of the malfunction restart the test on the failed cell (or cells).
Recovering from a Power Failure
The instrument software records data at periodic intervals. This data is used to assist in recovering from
power failures and instrument restarts.
If testing is interrupted after the instrument has restarted testing will resume from the point at which it was
interrupted.