GT-FIRE
PORTABLE GAS DETECTOR
67816
Revision D
24
5. Alarms
Alarm set-points (instantaneous, STEL and LTEL) are factory set. It is important to verify that the
set-points are in accordance with your company’s requirements and with local health and safety
legislation.
5.1. Instantaneous Gas Alarms
• When an alarm set-point has been reached, the audible and visual alarms will activate to
alert the user.
• Alarms only operate once the monitor warm-up is complete.
• All gas alarms are configurable to meet the specific needs of the user.
Refer to the table of
Default Set-Points of Gas Alarms
for more details.
5.2. Time-Averaged Toxic Gas Alarms
In Confined Space mode the monitor also calculates the Short-Term Exposure Limit (STEL) and
Long-Term Exposure Limit (LTEL / TWA) for toxic gas ranges.
Note: A time-averaged value is the mean average gas level over a rolling period.
The STEL is 15 minutes and the LTEL/TWA is 8 hours. In accordance with legislation,
this requires the time weighted averages to be averaged over a full period whether
the monitor is ON or OFF. Such averaging essentially makes the monitor single user
applicable. An option is available to restart the averaging after each monitor switch-
off, making it multiple user applicable.
Note: Because readings are averaged, it is possible to get a ‘live reading’ of zero and
have a LTEL or STEL alarm active.
Refer to the table of
Default Set-Points of Gas Alarms
for more details.
Leak Test
Confined Space
CH
4
O
2
CO
H
2
S
CH
4
O
2
CO
H
2
S
Warning
20ppm
HiHi
10%
10%
23%
35ppm 15ppm
LoLo
19.5%
LTEL / TWA
30ppm
5ppm
STEL
200ppm
10ppm
Default Set-Points of Gas Alarms
