RKI Instruments NP-204 - Manual (Page 7)

NP-204 RKI Instruments, Inc.
OPERATION
P r e p a r a t i o n
Normally the NP-204 requires very little preparation before use. Before using the instrument, follow
the steps listed below:
S t a r t - u p
1. Mechanical Zero
Before turning the instrument on, set it on a flat surface and verify that the meter
reading is exactly on zero. If necessary, turn the Mechanical Zero adjustment to bring
the reading to zero. The mechanical zero adjustment is located centered directly
underneath the meter.
2 . Battery Check
Turn the range switch to the VOLT ADJ. position. Lift and turn the VOLT ADJ. knob to
bring the meter reading exactly to the red ”Volt Check” line indicated on the meter by
a red “V” and line near the top of the scale. Turning clockwise will increase the voltage
reading.
If you are unable to adjust to the voltage up the red “volt Check” line, replace or
recharge batteries before use. Do not attempt to use the instrument if the
voltage cannot be set high enough.
3 . Flow System
Attach the hose to the inlet fitting on the left hand side of the instrument, and the
sample probe to the end of the hose. Assure that the hose and probe fittings are secure.
Close off the inlet to probe with finger, and squeeze aspirator bulb. Bulb should remain
collapsed while probe inlet is sealed off with finger. If not, re-check hose and probe
fittings and re-tighten if necessary.
With probe inlet sampling from fresh air, squeeze aspirator bulb 5 times to flush out
any remaining gas from the instrument and sample line.
4. Zero (Low range)
Turn range selector switch to “L”. Lift and turn the ZERO ADJ. knob to bring the meter
reading to exactly zero. If unable to adjust to zero, filaments may need to be replaced
or sample system may not be fully flushed with fresh air.
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