RKI Instruments NP-204 - Manual (Page 8)

NP-204 RKI Instruments, Inc.
5 . Verify Response (Low Range)
To verify detection of combustibles use a controlled source of flammable vapor, for
example a bottle of isopropyl alcohol. For accurate testing of calibration, use a known
calibrating gas source, such as 50% LEL methane. (See calibration section of this
manual for calibrating instructions).
After verifying response, squeeze the aspirator bulb 5 times again to flush fresh air
through the system.
Caution
Do not use gas from a cigarette lighter to test response to combustibles. Do not use a gasoline
container or tank to verify response. Exposing the sensor to uncontrolled high concentrations of
gas in this manner will reduce response and sensor life.
WARNING
If the NP-204 does not respond to these verifications, take it to a known “fresh-air” environment,
Sample the fresh air and Re-Zero the unit. Repeat the “Verify Response” procedure before using the
NP-204 in a potentially hazardous location. Do not attempt to use the instrument unless the
response is verified.
6 . Zero (High range)
Turn the range selector switch to the “H” (High) position. Allow a few seconds for
instrument to warm up, and verify the reading is exactly on zero. If it is not on Zero,
adjust the reading to zero using the internal adjustment before using the instrument.
Refer to the “Internal Adjustments” section of this manual for instructions on how to
adjust the High range zero.
7 . After the above steps are successfully completed, the instrument is ready to take to the
job site and use. It may be turned off until needed. When using, refer to the Normal
Operation section of this manual below.
Normal Operation
The NP-204 can now be used to check atmospheres for gas levels. Before each sample is taken, the user
should follow the following steps:
1 . Turn unit on to Volt Adj., and adjust voltage to the red Volt Check line on the meter,
using the Volt Adjust knob.
2 . Turn Range switch to “L” position, and adjust the Zero to be exactly zero using the
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