Time Weighted Average (Twa); Turning Off The Orion Plus Multigas Detector; Warning - MSA Orion plus Mode D'emploi

Time Weighted Average (TWA)

• The TWA flag appears in the upper portion of the display to show
the average exposure since the TWA reading was reset.
• When the amount of gas detected by the Orion plus Multigas
Detector is greater than the eight-hour TWA limit, the:
• Alarm Sounds and Alarm Lights Flash
• TWA flag flashes.
The TWA alarm is calculated over an eight-hour exposure. Calculation
examples are as follows:
• 1-hour exposure of 50 PPM:
(1 hour x 50 PPM) + (7 hours x 0 PPM)
• 12-hour exposure of 100 PPM:
(12 hours x 100 PPM)
8 hours
NOTE: The accumulated reading is always divided by eight hours.
If the STEL or TWA alarm condition is reached while using
the instrument as a personal or area monitor, leave the con-
taminated area immediately; the ambient gas concentration
has reached the preset STEL or TWA alarm level. Failure to
follow this warning will cause over-exposure to toxic gases,
which can result in serious personal injury or death.

Turning OFF the Orion plus Multigas Detector

Push and Hold the ON-OFF button for five seconds.
• Gas readings end and the Hourglass displays.
NOTE: Releasing the ON-OFF/PAGE button before the five seconds
elapse returns the instrument to the Measure page.
3-12
8 hours
= 150 PPM

" WARNING

= 6.25 PPM