09420A DCN8343
Teledyne API Model 480M O
3
Monitor User Manual
55
8.2.1. SENSOR OK
The Sensor OK LED indicates the status of the O
3
sensor module in the monitor.
The normal state of this LED (or Status Output) is On. If this LED remains off after
the normal warm-up period, then a failure has occurred, and the monitor should be
removed from service and repaired.
The most common cause of this warning is a failure of the UV LED. If the UV LED
intensity has dropped to a level that cannot meet the specified values, then it should
be replaced (Section 7.6).
8.2.2. INVALID READING
The Invalid Reading LED indicates that the instrument is reading a value that
cannot be represented properly on the analog output. Since the analog output is
limited to 0-5V (or 4-20mA), it cannot properly represent negative values, or values
in excess of the full-scale range.
If the monitor is consistently reading negative values, then a zero calibration should
be performed, see Section 5.2.3.2.
If the monitor is consistently reading values in excess of the full-scale range, then
the range value should be adjusted higher. See Section 5.2.4 for details on setting
the range value.
8.2.3. CHECK LAMP
The Check Lamp LED indicates that the UV LED intensity has dropped to a level
where the UV LED needs to be replaced (Section 7.6); the Sensor OK LED will
also turn off, indicating that the monitor must be immediately serviced or taken off-
line.
8.2.4. PNEUMATIC ERROR
The Pneumatic Error status indicates that one of the pneumatic parameters, flow or
pressure, has gone outside of normal ranges. Note that this is a non-critical warning.
Unless it is also accompanied by Sensor OK LED turning off, the instrument does
not need to be removed from service at this time.
The first step in troubleshooting a Pneumatic Error is determining which parameter
has caused the warning. At the monitor front panel, navigate to the VIEW menu
(See Section 5.2.2). Examine the Flow and Pressure values and compare them to the
limits described in Table 8-1 and take appropriate action as described below.
8.2.4.1. P
RESSURE
T
OO
H
IGH
The monitor inlet is being pressurized. The monitor inlet should be allowed to
sample gas at ambient pressure. Disconnect all sample lines from the monitor and
read the pressure again. If the value then drops to within the acceptable range, then
one of the sample lines is at elevated pressure.
If the inlet is being pressurized, then the design of the sample system should be
reviewed and corrected.
