26
GS700 USER GUIDE
TWA Alarms
• A Time Weighted Average (TWA) gas level, is the
average gas level measured over a specific period
of time.
»
Short Term Exposure Limit (STEL) - 15 minutes
»
Long Term Exposure Limit (LTEL) - 8 hours
• Toxic gases have STEL / LTEL alarm set-points.
• The examples below show:
»
H
2
S STEL alarm, with a gas reading of 12PPM and a STEL alarm flag.
»
CO LTEL alarm, with a gas reading of 38PPM and a LTEL alarm flag.
Alternates with
Alternates with
i
Live readings are shown (not calculated averages).
Over Range Alarm
• In the event of the flammable gas (LEL) sensor
being exposed to a high concentration of flammable
gas, the instrument has an over- range alarm.
• If the LEL sensor is exposed to a gas reading above
100% LEL, EEE will alternate with the HIHI alarm
flag.
Alternates with
