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PortaSens II
Gas Detector
C16 Leak Detector
O & M Manual
Rev. G, 11/07
- 22 -
SETTING DISPLAY VARIABLES
Three display variables may be adjusted on the
PortaSens II
. The adjustments include
display averaging, display blanking, and display range. To adjust display variables, start from
display PD2 (see page 20). Press the key marked DISP. The display will change to VD1 below.
Pressing the MORE key will toggle back and forth between VD1 and VD2, your starting point for
adjusting the three display variables.
VD1
P
0
PPM
NH3
MORE AVG BLANK DONE
Initial display for adjustment of display averaging and
blanking.
↓
M
↑
↓
M
↑
VD2
P
0
PPM
NH3
MORE RANGE DONE
Second display for adjustment of display range.
Display averaging is done to dampen out some of the normal variations in sensor
readings, resulting in a more stable display value. The lower the averaging value, the faster the
display will change and the more display variability will be observed. The higher the averaging
value, the slower the display will change and the more display stability will be observed. Press
the AVG key and follow the instructions in VD3 below to set the desired averaging. The gas
concentration is calculated 20 times a second using a running average. The number set in the
averaging routine represents the number of measurements averaged to obtain the displayed
value.
VD3
P
10
SAMPLS
ABORT INC DEC SAVE
Use the INC key to increase and the DEC key to decrease
the number of samples. Press SAVE to change or ABORT to
return to VD1.
Display blanking refers to the lowest value shown on the display. The C16 allows you to
adjust the blanking if you wish to eliminate values close to zero that have no real significance.
Normally, blanking values less than 2% of full scale simply eliminates the display of low values
that are just as likely to be sensor noise as they are real gas values. For example, when using an
ammonia detector over a range of 0-200 PPM, displaying values below about 4 PPM results in
the display of meaningless numbers because the ammonia sensor zero is only stable to about 2
PPM. To adjust the blanking, press the BLANK key and follow the instructions in VD4 below.
VD4
P
4
PPM
NH3
ABORT INC DEC SAVE
Adjust the blanking value using the INC key to increase and
the DEC key to decrease the blanking value. Press SAVE
when done. Press ABORT to return to VD1.