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D. BOOSTING SENSOR SENSITIVITY
The sensitivity of a natural gas sensor generally decreases with use because some
substances, for example, silicones, tend to poison the catalyst. A catalytic sensor can often be
restored to its original sensitivity by periodically cleaning it with Boost Gas available from
Bascom-Turner. The sensor does not need to be removed from the detector for boosting. The
catalytic combustion sensor's sensitivity can be boosted many times, but if boosting must be
performed too frequently on a given detector, its methane sensor is best replaced.
The following stepwise procedure will boost the sensitivity of the catalytic combustion
sensor and then calibrate the sensor.
1.
Remove the black #4-40 screw from the right side of the detector (see Figure 3).
2.
While pressing the push-button with a small rod (3/32" in dia. or less), move the
selector switch from OFF to TRACK GAS and wait 2-3 seconds before releasing
the button
"bGAS"
should be displayed.
Note:
If 1 or 2 dots appear repeat step 2.
3.
Connect the boost gas assembly (Part No. BGA-302) to the dust and water-block
filter on the hose of the Gas-Ranger and turn on the gas valve. The display should
stop flashing
"bGAS" "nogo"
and display
"bGAS"
with the pump off for 5 minutes.
4.
When the detector beeps and displays
"End"
, turn the boost gas tank valve off and
disconnect from the dust and water-block filter.
5.
Press the RESET button and allow the detector to purge out the boost gas with clean
air.
6.
Press the RESET button again and the detector will auto zero the sensors. When
finished,
"End"
is displayed.
7.
A calibration must now be performed without moving the selector switch from the
TRACK GAS position. After
"End"
appears on the display and the instrument
beeps, insert the tip of the standard probe partially into the outlet port of the gas
dispenser. If a manual calibration apparatus (for example, Part No. PCA-302) is
used, attach the detector's water-block filter to the threaded hose barb (TB-512) with
the regulator's valve off and wait for
"bloc".
After
"bloc"
appears on the detector's display, push the probe completely into the
dispenser port. The
"bloc"
display will be replaced by
"go"
and the instrument will
proceed to calibrate the catalytic combustion and CO sensors.
If a manual apparatus is used, open the flow regulator's valve and observe
"go"
on
the display.
The detector's display will show
"GAS 2"
while the catalytic combustion sensor is
being re-calibrated and
"CO"
when the CO sensor is being re-calibrated.
