Time Weighted Average (Twa Page) - MSA ALTAIR 5 Manuel D'utilisation

2.4.4 Time Weighted Average (TWA Page)

If the TWA alarm activates, leave the contaminated area
immediately; the ambient gas concentration has reached the
preset TWA alarm level. Failure to follow this warning will
cause over-exposure to toxic gases and persons relying on
this product for their safety could sustain serious personal
injury or death.
This page shows the average exposure over 8 hours since the
instrument was turned ON or the TWA reading was reset. When the
amount of gas detected by the instrument is greater than the TWA limit:
MONOCHROME DISPLAY
STEL
• Alarm sounds
• Alarm lights flash
• "TWA ALARM" message flashes.
To Reset the TWA Readings
1. Access the TWA Page.
2. Press the
The TWA alarm is calculated over an eight-hour exposure.
TWA Calculation Examples:
• 1-hour exposure of 50 ppm:
(1 hour x 50 PPM) + (7 hours x 0 PPM)
• 4-hour exposure of 50 ppm and
4-hour exposure of 100 ppm:
(4 hours x 50 PPM) + (4 hours x 100 PPM)
• 12-hour exposure of 100 ppm:
(12 hours x 100 PPM)
This page can be de-activated through MSA Link.
2-12
! WARNING
button.
▲
8 hours
8 hours
8 hours
COLOR DISPLAY
= 150 PPM
= 6.25 PPM
= 75 PPM