12 • OPACITY MONITOR MANUAL IM-A-08740-05 •
3.0 Operation & Maintenance
3.1 Displays and Indicators
3.1.1 Continuous Display Screen
When power is applied to the unit, the continuous display screen lights. It provides a continuous display of
particulate density from 000% Opacity (no particulates detected) to 100% Opacity (particulates are dense enough
to block all light), in 1% increments. The display window indicates the parameters and messages shown in Figures
10-13 in this manual.
3.1.2 Indicator LED Lights and Status Messages
The green LED lights and the “Clear” message appears on the rst line of the display to indicate that opacity
is below alarm trip point. As soon as the trip point is exceeded, the green LED and “Clear” message go out and
the yellow LED and blinking “Smoke” message come on. On the second line of the display, the alarm delay timer
countdown appears. The red LED and blinking “Alarm” display are activated if the excessive opacity persists
after the alarm delay period expires. If automatic alarm reset mode is selected, the Clear message and green LED
will resume after the smoke has cleared to the point that the monitor detects an opacity percentage less than the
alarm trip point. If manual alarm reset mode is selected, press the reset button to reset the alarm in all Standard
and Overre Air Timer models. See Figures 10 and 13.
For NYC models equipped with the 2-minute shutdown and alarm options, reset both the main and NYC
alarms by rst pressing the reset button, and then pressing the “Dec” key to reset the NYC alarm, and the “Inc”
key to reset the main alarm. If the main alarm is in automatic reset mode, it will be necessary to reset only the NYC
alarm. See Figure 11.
3.1.3 Output Functions
A 4-20 mA signal corresponding to 0 to 100% opacity provides for remote recording, control, or indication.
SPDT alarm contacts are provided for remote alarm or control. The alarm relay is normally energized for fail safe
operation. Refer to lines 11a through 11c on Figures 11, 12, and 13 for calibration of the retransmitted output.
Note that the output can be varied from the low (4 mA dc) and high (20 mA dc) values by ±0.5 mA dc.
3.2 Field Conguration on Continuous Display Screen
The scrolling display permits the operator to view and change parameters. Press the “Enter” button repeatedly
to scroll through the parameters, which appear on the bottom line of the display. With a parameter visible, press
the “Inc” button to increase its value. Press the “Dec” button to decrease its value. The new value becomes
effective immediately: pressing “Enter” again brings up the next parameter.
After 10 seconds of inactivity, the display reverts to the default screen except during calibration mode.
Following an alarm event, press the “Reset” button to clear the “Alarm” message and restore the “Clear”
message to the display if the unit is a Standard or Overre Air Timer model congured (on the printed circuit
board) for manual alarm reset. If the unit is congured for automatic alarm reset, the “Clear” message will replace
the “Alarm” message automatically as soon as the excessive opacity is cleared.
For NYC models equipped with the 2-minute shutdown and alarm options, reset both the main and NYC
alarms by rst pressing the reset button, and then pressing the “Dec” key to reset the NYC alarm, and the “Inc”
key to reset the main alarm. If the main alarm is in automatic reset mode, it will still be necessary to reset the NYC
alarm.
The scrolling display includes the parameters and messages shown on Figures 10 through 13.
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