13 • Operation
Model GX-2001 Operator’s Manual
4. To return to Measuring Mode, normal operation, press and release the
MODE/POWER button until the normal screen is displayed.
NOTE: While in Peak Reading Mode, if no control button has been
pushed for about 15 seconds, the Model GX-2001 returns to
Measuring Mode automatically.
Displaying STEL and TWA Readings
With the Model GX-2001, you can display STEL and TWA readings for H
2
S
and CO. STEL is an acronym for short-term exposure limit, and it shows
the average reading for H
2
S and CO during the last 15 minutes. TWA is an
acronym for time-weighted average, and it shows the average reading for
H
2
S and CO during the last eight (8) hours. If eight (8) hours has not
elapsed since the last time the STEL/TWA readings were cleared, the TWA
is still calculated over eight hours, with the missing time assigned a zero (0)
value for the readings.
1. Make sure the Model GX-2001 is in Measuring Mode. The four target
gasses should be displaying in sequential order on the LCD.
2. Using the DISP button, display either H
2
S or CO on the LCD.
3. With either H
2
S or CO displayed on the LCD, press the MODE/POWER
button twice to put the Model GX-2001 in STEL Reading Mode. “STEL”
displays next to the time reading on the LCD.
4. To put the Model GX-2001 in TWA Reading Mode, press the MODE/
POWER button again while the unit is in STEL Reading Mode. “TWA”
displays next to the time reading on the LCD.
5. Press the DISP button to toggle between the TWA reading for H
2
S and
CO.
6. To return to Measuring Mode, normal operation, press the MODE/
POWER button.
NOTE: While in STEL or TWA Reading Mode, if no control button has
been pushed for about 15 seconds, the Model GX-2001 returns to
Measuring Mode automatically.
