Carbon Monoxide Detection Devices Part 1

The home is a place where we see a lot of Carbon Minoxide (CO) sources from the garage, uitility room, any open flame, the venting of the products of combustion can be suspect, and the less thought of BBQ( smokers especially), space heater and outdoor pool heater. If you are a smoker you already carry a level of CO in your blood stream from inhaling burning tobacco.  The task of detecting CO is not without controversy. There are ceiling mounted CO detectors that are combination smoke/CO detectors that many builders will put into homes.  There are CO detectors people put on bedroom levels.  And these detectors will only alert the home dwellers when they are in an alarm mode.   Otherwise they give you no indication of danger.

Typical alarm levels warnings are at 70, 100, & 150 parts per million (PPM)  If you are breathing say 35 PPM in your home nothing would be reported.  And the quiet assumption is that this is not harmful.  But there are two health warnings that say that 8 hours at this level is harmful for your health.  So why do people buy CO detectors that will not tell them what they are actually inhaling?  We will get to health warning levels in the next blog.  The assumption of neglegible harm is simply wrong at any level below 70PPM and higher than 9PPM.  

Complicating issues are the Underwriters Labratory (ULC) of Canada, and Canada Safety Association (CSA) will not endorse anh CO dection device when it will alarm at 30 PPM or below as this has previously led to false alarms for those who choose to hook up alarm systems with local fire departments.  It should be noted that on the back of and inside packages of CO detectors there are explanations for how the alarms work.  There are three main types of CO detection whose explanation is not germaine to writing about how they work. There is usually a delayed reaction to an alarm before a visual alarm is seen through flashing LEDs and colours in some cases.  This actual visual cue can be seen after an hour of initial detection so the device reads a saturation point over against a localized reading. Another 1/2 hour can lapse before an audible warning is given.   So here you actually get to breathe CO for quite awhile before you know it.

As the levels of alarm go up corresponding to increases in PPM, the time taken for an alarm to show visually takes less time.  The audible level also has a corresponding less time lapse as well.  The intensity of the flashing or colour coordination increases, and the audible alarm repeats faster indicating a worsening of air quality due to the increasing presence of CO. That part is not a concern to this writer. 

There is also a warranty or best before date on these CO detectors that are easily forgotten once they are plugged in.  I suggest this gets marked on the front of the CO dectector or monitor with a permanent marker so it is disposed of when it is past the due date.  The industry has shown that CO detectors after their prescribed life cycle work at or below 50% of the time, and worsen as time does on.  Typically there are toxic chemicals inside that are not stable after their due date.  So they need to be disposed of at the local dump site's hazardous disposal section.

Testing procedures for the CO detectors are frequently a button to depress which will signal a red "no good" or a green "okay."  But this is deceiving as this only tells the user that the electronic component of the alarm works, and says nothing about the actual CO sensor itself.  So in addition to a deceptive lack of indication of the air the home dweller is actually breathing, there are false testing mechanisms that say nothing about the CO sensor itself.  When a local CO tester for Firefighters, HVac, and home CO devices was questioned about the sensor portion, he cynically warned that the testing itself renders about 50% of these devices useless. This is even more reason to make sure you use these detection devices with wisdom re their best before time, but also what you want in terms of safe home protection from CO.

The best tool for CO detection is actually better referred to as a CO monitor.  What is unfortunately confusing is that in stores they are actually still called CO detectors.  CO monitors differ in that they give actual LED readings of the air, usually in four second delays.  Close enough to real time that it is a much better indicater of what the home dweller is breathing.  So instead of a blank screen one actually reads "0" PPM, and  is likely unaware there is from 5-10 PPM CO in a kitchen with a gas stove since few people always turn on the fan when a gas element is turned on for the stovetop.

Having clear readouts of CO gas allows the home dweller to think about what the source of CO might be and from where it is entering the building envelope.  This way you can address the source, increase ventilation by opening windows and or doors, and talk about whether you should contact a trained emergency personnel who has both more sensitve equipment and knows how to diagnose symptons and return the home to a safe and breathable indoor air.

It does not take much CO to harm or even kill a home dweller.  And the smaller the body - pets and infants, then toddlers or children before we graduate to a adult sized body. 

Placing CO monitors and health warnings will follow in subsequent blogs.  A prepared and trained home inspector will carry home inspection tools such as a portable CO device for both ambient air testing and time average studies over days, and even weeks, for subsequent computer anaylsis. Home safety is job one for this home inspector pro so poking around a furnace vestibule with a hand held mirror is just not good enough.

Kurt Weinberger -home inspector for EnergGREEN Home Inspection Services. you can contact the kitchenrwaterloohome at 519-888-0852, or  Look for my series on Carbon Minoxide and the Home, and Carbon Minoxide Detection.

Submitted by KurtWeinberger on Thu, 02/16/2012 - 19:17.
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