ALTAIR 2X
13
Description
GB
Time Weighted Average (TWA)
The TWA alarm is calculated over an eight-hour exposure.
TWA calculation examples:
1 hour exposure of 50 ppm:
4 hour exposure of 50 ppm and 4 hour exposure of 100 ppm:
12 hour exposure of 100 ppm:
If the device is ON for less than 8 hours (480 minutes), the balance of the minute
ppm values is set to zero.
(1 hour x 50 ppm) + (7 hours x 0 ppm)
= 6.25 ppm
8 hours
(4 hours x 50 ppm) + (4 hours x 100 ppm)
= 75 ppm
8hours
(12 hours x 100 ppm)
= 150 ppm
8 hours
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