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appears to slow down to around 0.1 mA/sec. If the output signal rises
above 20 mA, immediately begin adjusting the span pot counter-
clockwise to lower the mA output signal as the maximum output is 26
mA. The rise in 4-20 mA output signal will begin to slow down around 10
to 30 seconds after gas is applied as it begins to approach a peak value.
Turn the span pot until output reaches 20 mA ±0.5 mA (200 mV ± 5 mV)
even though the signal may be slowly changing. Remove the calibration
adaptor and shut off the gas. Do not gas the sensor for more than 2.5
minutes. If the mA output signal begins to drop quickly during the
gassing phase, (0.2 mA/sec.) too much gassing time has passed and the
process must be repeated.
Cal gas flow must be in the direction of the arrow shown on the EC-FX
calibration adaptor. Connect the regulator hose to the "Inlet port" side of
the adaptor according to the air flow direction arrow molded into the
plastic housing.
(Inlet side) ○→○ (Exit port side).
NOTE: The rise in 4-20 mA output signal will typically begin
to slow down around 30 seconds after gas is applied as it
approaches a peak value. If the 4-20 mA signal peaks then
begins to drop, quickly adjust the span pot to 20 mA±0.5 mA.
Do not gas for more than 2.5 minutes. If a signal peak is not
reached within 2 minutes, the sensor may need additional
time to stabilize, the adaptor may not be properly seated on
the sensor with the O-ring, or there may be other issues
specific to the site or the application.
NOTE: In some cases, the signal may begin to drop quickly
after it peaks, adjust the span pot until the output reaches 20
mA ±0.5 mA even though the signal may begin to drop slowly.
NOTE: For an EC-FX-NH3 detector with the LCD option,
once cal mode is initiated, "Apply gas" will show on the
display. For best accuracy, the span pot should be adjusted
during the 2 minute timer. Begin adjusting the span pot when
the NH3 reading begins to slow down to 0.1mA/sec
(1mV/sec). This will likely take place before the 2 minute timer
will expire. Use a meter as described on page 21 for mA
output readings during calibration, not ppm levels as shown
on the LCD display. Once cal gas begins to flow, a 2 minute
reference timer will indicate when the sensor has reached the
maximum allowed gassing time. If the signal has not peaked
or slowed down to 0.1 mA/sec. within this time, the sensor
may need additional time to stabilize or there may be other
issues per note above. After 2 minutes of gassing has
occurred, the display will indicate "Spansnsr". If the sensor is
not ready to span or peaked in signal level when the
"Spansnsr" is shown on the display, the sensor may need
additional time to stabilize or the adaptor may not be properly
seated on the sensor. If the sensor was able to span within
the 2 minute time period, this mode can be exited at any time
OPERATOR MANUAL
24
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Troubleshooting
