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Coverage
Guidelines for sensor placement of diffusion type sensors are based on the reasonable delay for gas to get from the source to the sensor. All
sensors are created equal in this regard.
• For air quality control of exhaust emissions and accumulations of toxic gases the generally acceptable maximum radius of coverage is
50 feet (15 meters). Approximately 7500 square feet (700 square meters).
• For leak detection of combustible gases, ammonia, refrigeration gases the maximum radius is 30 feet (10 meters) since they can
escape more quickly and the risk is greater.
The radius of coverage of any sensor does not extend beyond any obstruction that impedes natural circulation of air. This includes walls,
stairs, elevators, shelving with solid fill, tool chests, etc. The sensor must "see" the area of coverage; if not, another sensor(s) is required.
Mounting Heights
Mounting heights for gas sensors are based on their density, relative to air. There are three groups:
1.
Lighter than air and will be more concentrated near the ceiling; hydrogen, methane (natural gas), ammonia, helium. Install at 1 to 3
feet from ceiling.
2. Similar density to air and will be diluted in air equally at all levels; - carbon monoxide, nitrogen dioxide, hydrogen sulfide, oxygen,
carbon dioxide. Install from 3 feet (1 meter) off floor to one half of the ceiling height. For vehicle emissions carbon monoxide
detectors combined with nitrogen dioxide detectors are installed at 3 to 5 feet (1 to 2 meters) from the floor when the ceiling is 7
to 10 feet high. If the ceiling height is higher than 10 feet, for example for heavy equipment, the carbon monoxide detectors are
installed at 3 to 5 feet (1 to 1.5 meters) from the floor and the nitrogen dioxide detectors should be installed at 50% of the ceiling
height and above the vehicle height. If the exhaust pipes of diesel vehicles are below the vehicles, then the nitrogen dioxide detectors
should be installed at 3 to 5 feet (1 to 1.5 meters) from the floor. In all cases the detectors must be installed above obstructions
blocking circulation of air in front of the detectors; example, maintenance garages in automobile dealerships where tool chests, work
tables and storage racks typically line all walls.
3. Heavier than air and will concentrate near the floor; - HFCs, HCFCs, propane, chlorine, most organic vapors (consult Opera),
butane.
For all types of sensors avoid drafts, obstacles, aerosols, silicones. Place sensors in the center of its coverage area as much as possible.
OPERATION
Screen Display
The LCD shows the type of gas and the current gas concentration. If two sensor modules are installed, the display will alternate between
them.
The bottom left corner will also display the alarm status;
1 indicates alarm 1 on, per settings 0, 1, 2 or if activated by another sensor on the CAN network via setting 36. This is usually the low
gas level alarm.
2 indicates alarm 2 on. Per settings 3, 4, 5 or if activated by another sensor on CAN network per setting 37.
3 indicates alarm 3 on. Per settings 6, 7, 8 or if activated by another sensor on CAN network per setting 38. Alarm 3 activates the
sounder and strobe.
M indicates manual override mode on. Useful to start ventilation system without the risk of leaving it on too long in cold weather. From
the home screen, press and hold ↑ for 5 seconds to start. Then click again to increase time from 5 to 60 minutes. This activates alarm 1,
(or 2, and 3 per setting 69) and sends alarm transmit messages (settings 9-17) to other sensors on the CAN network. The unit will return
to automatic operation after the time runs down. To cancel manual mode press ↓ several times to reduce time left to run. It will take a few
seconds to stop.
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