What is the correct mounting height for a carbon monoxide detector

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All our gas safety alarms have sensors that measure specific gas levels in the air. Because some gases are heavier than air they will tend to “pool” at different heights in an enclosed area. Therefore, when mounting a gas safety alarm you should to mount the sensor at a height closer to where the gas will be sensed first. You can do this by knowing the weight of your target gas relative to the air in the room.

Below is a chart listing the molecular weights of various gases. Note that the molecular weight of fresh air is approximately 28.9. Gases with higher molecular weights will tend to rise in an enclosed area or room, whereas gases below will tend to sink toward the floor.

When deciding where to mount a gas safety alarm sensor, find the gas you are monitoring on the list, then note whether it is heavier or lighter than air. This will tell you where to mount the sensor.

For example, an oxygen sensor should be mounted higher on the wall while a carbon dioxide sensor should be mounted 18-24 inches from the floor.

While this chart should be used as a general guideline, when using any gas safety monitor always check the manufacturer's instructions first before mounting the sensor.

What is the correct mounting height for a carbon monoxide detector

  • Tags: Oxygen Depletion

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► What should the mounting height of the sensors be?

The sensor mounting height depends the type of application and on the density of the target gas relative to air. Heavier than air gases should typically be detected 6 inches from the floor, lighter than air gas sensors should typically be placed on or near the ceiling, and gases which have a density close to that of air should have sensors installed in the "breathing zone" 4 - 6 ft (1.2 - 1.8 m) from the floor. The breathing zone refers to the area 4 - 6 ft (1.2 - 1.8m) from the floor, where most human breathing takes place. This is a good default location for sensors, as many gases often disperse well in air.

Sensors should be placed near the source of the gas if possible. For example, near the compressor or piping.

Sensors should not be placed near ventilation fans or openings to outside. They should be placed in areas where there is good air circulation, but not in the path of rapidly moving air. Pay particular attention to "dead air spots" where there is little or no air movement.

Consideration should be given to accessibility for calibration when locating sensors. For example, a sensor mounted 30 feet (9 m) off the floor will be difficult or even hazardous to service.

Some applications may require the sensor to be mounted at a different height than indicated below. If you have any questions, please ask your Regional Sales Manager or our Technical Service Department.

Gas detectors should be mounted upright on a vertical surface like a wall, column or beam - do not mount upside down, sideways or flat on the floor. 

Typical Mounting Heights for Common Gases

On or Near the Ceiling:
• Ammonia (NH3)
• Hydrogen (H2)
• Methane (CH4)
 

Breathing Zone (4 - 6 ft / 1.2 - 1.8 m above floor):
• Acetylene (C2H2) 
• Carbon Dioxide (CO2)
• Carbon Monoxide (CO)
• Ethylene (C2H4)
• Formaldehyde (CH2O)
• Oxygen (O2)
• Nitric Oxide (NO)
• Nitrogen Dioxide (NO2)
• Phosphine (PH3)
• Silane (SiH4)

• Hydrogen Sulphide (H2S) (3 ft above floor)

Near the Floor (6 in / 15 cm above floor):
• Acetone (C3H6O)
• Alcohols
• Benzene (C6H6)
• Butane (C4H10)
• Chlorine (Cl2)
• Diesel Fuel
• Ethanol or Dimethyl Ether (C2H6O)
• Fluorine (F2)
• Gasoline
• Hydrogen Fluoride (HF)
• Hexane (C6H14)
• Isobutane (C4H10)
• Isobutylene (C4H8)
• Isopropyl alcohol (C3H8O)
• Jet Fuel
• Methanol (CH4O)
• Ozone (O3)
• Propane (C3H8)
• Pentane (C5H12)
• Propylene / Propene (C3H6)
• Sulphur Dioxide (SO2)
• Toluene (C7H8)
• TVOC (target gas dependant)
• Xylene (C8H10)

Near the Floor (12 in / 30 cm above floor):
• Hydrogen Chloride (HCl)
• Hydrogen Cyanide (HCN)

• Refrigerants

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Do you mount carbon monoxide detector high or low?

Standalone carbon monoxide alarms are often placed low on the wall because they need to be plugged into an outlet that's near the floor. CO alarms can also have a screen that shows the CO level and needs to be at a height where it's easy to read.

Where is the best position for a carbon monoxide detector?

They are better off being fixed on the wall—ideally, secured at least 15cm away from the ceiling. And when placed in the same room as a possible source, it's better to place them between 1m and 3m away from the appliance.