RKI Instruments NP-204 - Manual (Page 9)

NP-204 RKI Instruments, Inc.
Zero Adj. knob.
3. Generally, when testing an unknown space or sample, it is recommended to have
the range selector switch in the H position. This helps to extend the life of the
Low range sensor by not stressing it with exposures to very high concentrations.
4. Attach hose and probe and check for leaks by holding finger over
probe inlet while squeezing aspirator bulb. Bulb should remain
collapsed if there are no leaks in the system.
5 . Insert probe into the space or atmosphere to be tested, and squeeze aspirator bulb
4 to 5 times. Watch meter and observe the maximum reading.
If reading is very low, and range selector switch is on the “H” position, remove probe
from test space and place in fresh air, squeeze bulb 5 times, then repeat steps 2 and 5
above.
6 . When test is completed, remove probe from the test space and place in fresh air.
Squeeze bulb 5 times to flush any test vapors out of the system, and turn instrument
off.
WARNING
If repeated tests are to be taken, it is necessary to periodically verify the battery voltage is
properly set (to the red Voltage Check line). If the voltage is not set properly, the instrument may
not provide correct readings.
Alarms
The NP-204 contains no audible or visual alarms.
CALIBRATION AND MAINTENANCE
The NP-204 requires only a few user adjustments. These are the zero and span for the low range and
high range sensors. The Low range span should be checked periodically ( preferably every use for
critical applications). The high range span needs to be checked only when the sensor is replaced.
The sensors need to be replaced if the span cannot be set to read the proper value, or if they cannot be
set to read Zero with the appropriate zero adjustment.
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