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8.1.2.3 Span Adjustment
A) Connect the flow regulator to the span gas cylinder (or other span gas source).
B) Apply span calibration gas while monitoring the output of the sensor. Allow output to stabilize.
C) Adjust the span potentiometer until the meter reads the appropriate current ±1.5%.
D) Turn off the span gas and remove from the flow regulator.
NOTE:
To determine the appropriate output in mA DC for a given concentration of
calibration gas, or to convert current mA DC readings to a specific gas concentration;
use the following calculations:
Output (mA) =
Concentration (ppm) =
8.2 Sensor Element Replacement
As the electrochemical sensor ages, oxidation wears away the measuring electrodes. This reduces the
output of the sensor, requiring regular re-calibration. Eventually it will not be possible to adjust the span
potentiometer enough to bring the transmitter output to the correct level. When this happens the sensor
element must be replaced.
The sensor element is a small, plug-in cell with four pins on the bottom. The cell is shipped from the
factory in a sealed plastic cylindrical container. The sealed container prevents contamination of the cell by
gases, dirt, and other foreign matter prior to installation.
NOTE:
Wherever possible, do not remove the sensor from the sealed container until you are
ready to install it. This will maximize the life of the cell and minimize the warm up
time.
When you first remove the sensor from the container, a shorting wire will be across the connection pins.
This wire prevents degradation of electrodes during storage. When properly installed, the transmitter
supports this function whether powered or unpowered.
*CAUTION*
Before installing the sensor element, any shorting wires attached to the pins must be
removed.
Newly installed sensor elements should be left powered for at least 24 hours before calibration. Ammonia
(NH
) cells should be left for at least three days, preferably five days before calibration. This will allow the
3
sensor to burn off any gases that may have diffused into the cell before installation and to fully warm-up and
stabilize.
B71050-021-000-RB.doc
JUL. 18, 2007
QTS-6000 Series
Analog Transmitter/Sensor
Concentration (ppm)
Span (ppm)
(Output (mA) - 4)
The sensor will not operate with these shorting wires connected.
x 16
+ 4
x Span (ppm)
16
13
ELECTROCHEMICAL TRANSMITTER
PRODUCT MANUAL
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