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 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.