41
GasAlertQuattro
Computed Gas Exposures
Stopping a Gas Alarm
The low and high alarms stop when the ambient gas concentration
returns to the acceptable range.
Note
If alarms are set to latch, press
C
to reset the alarms.
The TWA and STEL alarms can be stopped either by
• deactivating and then reactivating
the detector, or
• clearing the TWA/STEL/peak exposure readings. Refer to
Viewing and Clearing Gas Exposures
.
a
Warning
Follow all safety procedures as defined by your
employer. Confirm with your supervisor before clearing
TWA and STEL alarms.
Computed Gas Exposures
a
Warning
To prevent possible personal injury, do not deactivate
the detector during a work shift. TWA, STEL, and peak
readings reset when the detector is deactivated.
Table 8. Computed Gas Exposures
Gas Exposure
Description
TWA
(H
2
S and CO only)
Time-weighted average (TWA)
based on accumulated exposure to
toxic gases averaged over a work-
day according to US OSHA or
ACGIH TWA method. Refer to
and
.
Default: US OSHA 8 hour moving
average.
User-defined TWA Period: 4-16
hour moving average.
STEL
(H
2
S and CO only)
Short-term exposure limit (STEL)
to gas based on a 5-15 minute
user-defined period.
* Peak
Peak concentration encountered
during a work shift.
* For oxygen, it is the highest or the lowest concentration
encountered.
