GT SERIES
1 INSTRUMENT, 7 APPLICATIONS
32
67112
Revision 10
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.
Alarm levels can be changed, refer to the
SET-UP SOFTWARE USER HANDBOOK (part no.
67162)
.
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 some modes the monitor also calculates the Short-Term Exposure Limit (STEL) and Long-Term
Exposure Limit (LTEL / TWA) for toxic gas ranges.
Refer to the table of
Default Set-Points of Gas Alarms
for more details.
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. The option is available to restart the averaging after each monitor switch-
off, thus allowing for multiple user application.
Note: Because readings are averaged, it is possible to get a 'live reading' of zero
and have a LTEL or STEL alarm active.
Default Set-Points of Gas Alarms
Methane
O
2
CO
H
2
S
LO
N/A
Disabled
N/A
N/A
LOLO
N/A
19.5% Vol
N/A
N/A
HI
Disabled
Disabled
Disabled
Disabled
HIHI
20% LEL
23% Vol
35ppm
15ppm
STEL
N/A
N/A
200ppm
10ppm
LTEL/TWA
N/A
N/A
30ppm
5ppm
