4
SD2-NH3
Installation
General Description
The SD2-NH3 is a single-point sample-draw ammonia sensor. This design
helps the sensor survive in continuous-exposure applications where other
diffusion-type electrochemical sensors simply fail and die.
This ammonia sensor utilizes proven electrochemical sensor technology for
accuracy. It is designed with special pump/valve sequencing to refresh the
cell with clean air to prevent ammonia saturation and extend the cell life.
An automatic reverse purge routine also helps self-clean the micron filter.
The SD2-NH3 has a 10-minute sampling rate, and the sample-draw cycle is
as follows:
2-minute sample time from the room being monitored. At the end of the
two minutes, the sample data is stored and held for the next 10 minutes
also while being transmitted via 4-20 mA output to the controller or PLC.
2-minute fresh air purge from outside fresh air source.
6-minute pump shut-off phase.
The standard detection range (0-50 ppm) of the SD2-NH3 sensor provides
monitoring of ammonia concentrations accurately down to 5 ppm without
false alarms.
The SD2-NH3 sensor provides an industrial standard linear 4/20 mA output
signal compatible with most gas detection systems and PLCs. The output
signal is not affected by drastic temperature and moisture variations.
All circuit boards are sealed in potting compound, protecting sensitive
electronic components and copper tracing from corrosion.
An external fresh-air sample tube and hardware are included with the SD2-
NH3. Tube length provided is five feet.
Locating the SD2-NH3
An important consideration when installing the SD2-NH3 is that it must be
easily accessible for occasional maintenance, and protected from physical
damage.
The sample air port should be mounted on the inside of the CA room and
penetrate through the CA room wall. The SD2-NH3 detector will connect to
it on the other side of the wall (see
Figure 1
on next page).
The fresh air port is located on the bottom the SD2-NH3 enclosure. This will
be the source of fresh air necessary for proper monitoring and longer cell
life.
The SD2-NH3 sensor can adequately monitor 1,200 sq feet.
Installation Guidelines:
•
Do not mount sample air port any farther then the supplied tubing and
hardware allows.
•
Mount sensor on a solid surface with minimal vibration.
•
Mount sensor thru the holes in the mounting flanges of the enclosure.
• Mount sensor in a general-purpose location only. Do not install in a
hazardous environment.
•
Mount sensor away from electromagnetic interference.
• Always mount sensor vertically with the sampling port at the bottom.
• Take air movement and ventilation patterns into account.
•
Keep sensor and wire runs away from mercury vapor lights, variable
speed drives, and radio repeaters to prevent electrical interference.
•
More than one sensor should be installed for highly critical locations.
