What’s wrong with this picture? Carbon-Monoxide is the ‘Silent Killer’

Earlier this year, we treated our youngest granddaughter to a winter event at a resort in the Dallas/Fort Worth Metroplex.

The excellent parking garage features high-tech checkout pavilions make the exiting fast and efficient. While parking, a nearby carbon-monoxide (CO) sensor caught my eye. This is what I saw.

The carbon-monoxide (CO) sensors were neatly and professionally installed. MSA (The Mine Safety Appliance Company) is my favorite manufacturer of these sensors. But, there is a problem. What is wrong in this picture?

Understanding atmospheric gasses is the starting point.

Over the last half-century, time and again I witness interesting installations of both carbon-monoxide and carbon-dioxide sensors. Consider the properties of these two gasses relative to air.

Detection of gasses is a little like fishing. You want to have your baited hook at the same level as the type of fish you wish to catch.

Because CO is slightly lighter than air, the best ‘fishing’ is between 5 and 8 feet above the finished floor (A.F.F.). Accumulation of this deadly gas will be at the upper reach of the affected confined space. If the silent killer is allowed to accumulate to a dangerous level at 2 feet A.F.F., the concentration at the level of human heads will be in jeopardy.

This same sensor can be configured to detect CO2 (carbon-dioxide). We measure the CO2 concentration to energy-efficiently operate ventilation equipment. Because this gas is slightly heavier than air, a CO2 should be installed near the floor.

Was the decision to mount these CO sensors a failure of either the engineer or the electrician? I don’t know. It is not my intent to shame anyone. My objective is to educate.

Questions? Send your questions via comment to this posting.

John White
Rockwall, Texas

Published by John White

A lifetime (over 50 years) of experiences with automation and control systems ranging from aerospace navigation, radar, and ordinance delivery systems to the world's first robotic drilling machine for the oil patch, to process-control systems, energy management systems and general problem-solving. At present, my focus is on self-funding HVAC retrofit projects and indoor air quality with a view to preventing infections from airborne pathogens.

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