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4. Alarms
4.1. Gas Alarms
When an alarm set-point has been reached, the audible, visual, and vibrating alarms will activate
to alert the users. All gas alarms are configurable to meet the specific needs of users and only
operate once the monitor warm-up is complete.
An alarm can be either 'latching' or 'non-latching'. A 'latching' alarm will remain active until reset
by the user by pressing and holding the R button after the gas readings have returned to a safe
level. A 'non-latching' alarm will reset automatically when the gas readings are safe.
4.1.1. Flammable LEL Alarm
Two alarm levels, 'HI' and 'HIHI', are available.
4.1.2. Oxygen (O
Three alarm levels, HIHI, LO, and LOLO, are available.
4.1.3. Toxic Alarm
The monitor calculates the Short Term Exposure Limit (STEL) and Long Term Exposure Limit (LTEL) –
known as Time Weighted Average (TWA) readings – for each toxic gas range. Each toxic range
has STEL and LTEL alarms, in addition to HI and HIHI alarms.
NOTE: A TWA value is the mean gas level exposure over a specific period. The
STEL is 15 minutes and the LTEL is 8 hours. Usually, TWA alarms mean the monitor is
for a single user. For multiple user applications, an option is available to reset the
STEL and LTEL after each monitor switch-off.
NOTE: All alarm levels – HI, HIHI, LO, LOLO, STEL, and LTEL – are factory set. The
user must set the levels in accordance with their company's procedures and with
local health and safety legislation. Alarm levels can be changed via the monitor set
up menu.
In the following examples,
shows a HIHI LEL alarm.
26: LEL HIHI Alarm
64171
Revision 12.1
) Alarm
2
Figure 25: O2 LOLO Alarm
Figure 25: O 2 LOLO Alarm
PORTABLE GAS MONITOR
shows a LOLO Oxygen alarm, and
PS200
Figure
19
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