N
2
O Portable Monitor
Operation
Instruction 3015-4787
7
4.
Observe that the
NEW TWA/twa
screen may appear, depending on
the configuration of the monitor’s TWA/twa function (refer to
Section 3.4 for detailed TWA operation).
5.
Observe the monitor starts counting down its warm-up period of
900 seconds (15 minutes).
6.
At the end of warm up, take the monitor to an area than contains
fresh air and press the
ENTER
button to fill the monitor’s internal
purge-air bag with clean, fresh air that is of the same temperature
and humidity as the area being monitored for gas. DO NOT fill the
purge-air bag in an area that is contaminated with N
2
O gas.
After the purge-air bag is filled, observe the following as the monitor makes
gas measurements in the area being sampled:
•
MEASURE
indicates when the monitor is actively measuring the
level of N
2
O gas at the sampling point. The screen to the right shows
that currently 100 ppm is being measured. The measurement cycle
runs for 4 minutes.
A log of up to 200 previous measurements can be viewed using the
PPM LOG
function (page 12), or printed as described in 3.15.
The
2ndUNIT
value (Blank, Peak PPM, Continuous TWA, or 8 Hr
TWA) is user-selected (refer to
2ndUNIT
function on page 13).
•
PURGE
indicates when the monitor is resetting its infrared detector
to a baseline of 0 ppm using the air contained in the monitor’s
internal purge-air bag. The purge cycle runs for 10 seconds.
The monitor will operate for approximately 40 minutes before the purge-air bag needs refilled.
When the message "PURGE AIR EMPTY" appears, take the monitor to a
clean, fresh-air
environment
and press the
ENTER
button to refill the bag.
Work with gas alarms and system faults as follows:
ALARM
(red) light turns ON if the detected gas level exceeds a programmed alarm point. An audible
alarm also sounds if the
AUDALRM
function is activated (page 11) Pressing the front panel
SILENCE
button turns OFF the audible alarm, but the
ALARM
light will continue to flash for as
long as the detected gas level is above the alarm point. The audible alarm will reactivate if the gas-
alarm condition is not cleared within the time period set by the
SILENCE
function (page 12).
FAULT
(yellow) light turns ON if a fault occurs (see Fault Code list on page 15). An audible alarm
also sounds if the
AUDALRM
function is activated (page 11). Pressing the front panel
SILENCE
button turns OFF the audible alarm, but the
FAULT
light continues to flash for as long as the fault is
present. The audible alarm will reactivate if the fault condition is not cleared within the time period
set by the
SILENCE
function (page 12). Both the
FAULT
light and audible alarm will automatically
turn OFF after the cause of the fault has been eliminated. A log of the last 30 fault events can be
viewed using the monitor’s
FAULTS
function (page 12).
MEASURE 2ndUNIT
100ppm N2O
PURGE 2ndUNIT
100ppm N2O
PURGE AIR EMPTY
(ENTER) TO FILL
PURGE AIR EMPTY
<ENTER> TO FILL
WARM UP
900
