Honeywell EC-FX-NH3 Instruction And Installation Manual page 31

If the sensor output is 0.5 mA: Indicates a fault condition has occurred.
• Most common — failed or disconnected sensor
• Hardware failure (pre-amp)
If the sensor output is erratic: Make sure that the unit is in clean,
ammonia-free air.
The detector has been factory zeroed and spanned. If the zero has
become unstable, and there are no interference gases, the most likely
problem is a depleted sensor or a new sensor with high gain left over
from a previous sensor that was adjusted for aging. If span calibration
has not been performed with the new sensor, turn span pot down (see
Figure 7, Note 1 on page 26), or counterclockwise, 3 full turns. This
will decrease the sensitivity and reduce the zero calibration of the new
sensor. Calibration is required after this adjustment.
Electrical Interference: This sensor has been designed to be highly
resistant to EMI/RFI using multiple stages of filtering and protection.
However, in extreme environments, some noise pickup can occur directly
through the sensor. Ensure that the bare shield wire of the instrument cable
is connected to the terminal block marked SHLD at the sensor (not touching
the metal enclosure) and properly grounded at the readout unit.
Interference Gases: The EC-FX-NH3 is designed to be quite specific to
ammonia. However, some other gases can affect the reading. Phosphene,
methyl mercaptan, and hydrogen can give a slight upscale indication.
Bromine, ozone, fluorine, chlorine, and nitrogen dioxide can give a slight
down-scale indication. Contact Honeywell Analytics if any of these gases
are present in your application.
OPERATOR MANUAL
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