13
d.
When prompted to insert a tube, open both ends of a benzene filtering tube using the tube tip
breaker, taking caution to protect eyes and hands from sharp glass pieces.
e.
Unscrew the top section of the tube holder, insert the tube with the arrow pointing towards the
instrument, and screw the top section back on.
f.
Briefly hold a finger on the probe tip and listen for a strain on the pump, to ensure flow is
blocked and thus check for a good seal on the tube.
g.
Direct the probe to the sampling point and press the Up key to start a count-down timer. The
sampling time is 45 s at room temperature, but ranges from 30 s to 360 s depending on temp.
h.
Press Left at any time to abort the measurement.
Benzene Tube Measurement Time vs Temperature
Temp. °C
-10 to -6
-5 to -1
0 to +4
+5 to +9
+10 to +19
+20 to +30 +31 to +50
Temp. °F
+14 to 21 +23 to 30 32 to 39 41 to 48
50 to 66
68 to 86
88 to 122
Run Time
360 s
240 s
170 s
110 s
60 s
45 s
30 s
i.
Monitor the color of the tube through the holder window during the measurement. If at any time
the tube turns brown or greenish-brown for more than 2/3 of its length, the filtering capacity of
the tube may be exceeded and false high readings could result.
At the end of the sampling time, the screen shows the concentration of the current benzene test and
asks whether to continue on to a STEL measurement (using the same tube).
STEL Measurement
Press Left to escape back to Continuous Benzene Screening or Right to continue with STEL
sampling for a 15-minute countdown, shown in the upper left corner (“STEL” alternating with
remaining time). Note that the 15 minutes are shortened by the initial sampling time of 30-360 s.
The pump automatically slows down during STEL measurement to maximize the ability of the tube
to filter out interfering chemicals.
Benzene:
0.184 ppm
Continue And
Establish STEL?
