Heath Consultants Personal Surveyor (PS200 Series) - Manual (Page 53)

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 configurable to
meet the specific needs of different companies.
4.1.2 Over-Range Flammable Gas Alarm Function
The flammable sensor is designed for use in the LEL range
only. Exposure to high concentrations of flammable gas, such
as lighter fuel, can damage the flammable sensor. If the
flammable 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 configurable
to meet the specific 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 fitted to the instrument.
Additionally, two alarm levels ‘HI’ and ‘HI HI’ are available.
Note: A Time Weighted Average (TWA) value is the mean
average gas level over a specific 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.