Time Weighted Average (Twa) - Extech Instruments CO220 User Manual

CO DISPLAY PAGES
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Press the CO button to change the CO
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shown below for CO
TIME WEIGHTED AVERAGE (TWA)
TWA is Time Weighted Average (8 hours); the meter updates the reading every 60 seconds. If
the meter has been powered on for less than 8 hours, the TWA value will be the weighted
average of readings taken since the unit was powered ON.
SHORT‐TERM EXPOSURE LIMIT (STEL)
STEL is the Short‐Term Exposure Limit (15 minutes weighted average); the meter updates
readings every 60 seconds. If the meter has been powered on for less than 15 minutes, the STEL
value shows the weighted average of reading taken since the unit was powered ON.
LPS%
LPS% represents Liters per second per person.
CFM/P
CFM/P represents Cubic Feet per Minute per person.
, Max‐Min, TWA, STEL, IPS% and cfm/p.
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display page on the top‐tier LCD area. The pages are
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5 CO220-EU-EN V1.3 07/13