2
WARNING:
On a call, turn the instrument on outdoors, not indoors.
2.
ESSENTIAL OPERATING PRACTICE
Gas-Rover detectors are easy to use. A detector is turned on by pressing the left button; its
operation is controlled by three buttons whose function is shown on the display. The middle button
generally toggles “
Mute
” on and off. Double-clicking the middle button turns the backlight
continuously ON or OFF, depending on its previous state.
Pump.
Gas-Rover detectors have a built-in pump and depend on this pump for their
operation. If the pump is not functioning normally, the instrument will not function properly. It
is therefore essential to check the pump each time the instrument is turned on.
Pump Test:
Connect the probe you plan to use and turn the instrument on. After the
display shows “
Block Intake
”, block the probe at its intake to show
"Pump OK"
.
If
"Pump OK"
does not appear, tighten all connections and repeat the test. If a block is still
not observed, remove the probe and block directly the inlet. If
"Pump OK"
still does not appear,
return the instrument for repair.
A pump test can be carried out as above at any time during normal operation of the
instrument.
If there is any indication that the pump is not operating normally, the instrument
should not be used until repaired.
Filters.
Dust and water-block filters protect the sensors and the pump from dust and
accidental intake of liquid water. Just as a car would not be operated without air and fuel filters,
do not operate a detector without a filter on the probe.
Operation without this filter will
eventually degrade the sensors and the pump. It also voids the limited warranty.
It is essential that the filter be replaced monthly or sooner if it turns brown. Operation
without a filter will degrade the natural gas sensor and will void the warranty. Filters are available
from Bascom-Turner in packages of five, Part No. WF-505.
Models VGA-611 and VGA-612 require special filters available from Bascom-Turner in
packages of five, Part No. WF-705.
Zero Check.
All sensors drift to some extent over time. Sensor drift is corrected by
zeroing if the drift is within 0.1% vol. GAS (and 10ppm CO if the unit is equipped with a CO
sensor). If the drift is outside these limits, “
NO GO
” is displayed and the user is asked to autozero
the unit in “clean” outdoor air. The unit will re-zero unless the zero has drifted over 1% vol. GAS
(or 20ppm CO if the unit is equipped with a CO sensor), in which case the instrument must be
checked by a trained professional (the sensor may need replacement). Zero adjustment must be
done in clean air, for example, outdoor, otherwise a systematic error may be introduced in
subsequent measurements.
Test and Calibration.
Gas-Rover detectors must be calibrated periodically with gas of
known composition. The sensors depend on catalysts which lose activity during use. The
necessary frequency of calibration depends on actual use and on the concentration of catalyst
poisons, if any, in the sampled gas. This concentration is, of course, not generally known.
A detector can be tested with methane bump gas, available P/N: BG-211 (100ppm in air).
Such tests merely verify that the gas sensor(s) are in operating condition. To verify and adjust, if
necessary, their sensitivity they must be calibrated.