GMI PS241 - 4.1.1 Flammable LEL Alarm Limit; 4.1.2 Over-Range Flammable Gas Alarm Function; 4.1.3 Oxygen (O2) Alarm Limits; 4.1.4 Toxic Alarm Limits

4-3
ALARMS
4.1.1 Flammable LEL Alarm Limit
Two alarm levels, ‘HI’ and ‘HIHI’, are available, each with
different pitch and tone. All alarms are user congurable to
meet the specic needs of different companies.
4.1.2 Over-Range Flammable Gas Alarm Function
The ammable sensor is designed for use in the LEL range
only. Exposure to high concentrations of ammable gas,
such as lighter fuel, can damage the ammable sensor. If the
ammable gas readings exceed 100% LEL, a safety alarm
will be activated. The instrument should then be switched OFF
and returned to fresh air.
4.1.3 Oxygen (O
2
) Alarm Limits
Three alarm levels, ‘HIHI’, ‘LO’ and ‘LOLO’ are available, each
with different pitch and tone. All alarms are user congurable
to meet the specic needs of the end user.
4.1.4 Toxic Alarm Limits
When operating normally, the instrument 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 alarm. TWA alarms are programmable
for each toxic range tted to the instrument. Additionally, two
alarm levels ‘HI’ and ‘HIHI’ are available.
Note: A Time Weighted Average (TWA) value is the mean
average gas level over a specic period. The STEL is 15
minutes and the LTEL is 8 hours. Typically, TWA alarms make
the instrument single user applicable. An option is available
to restart the averaging after each instrument switch-off, thus
allowing for multiple user application.