Originally Posted by meck51
Yes, you do need to test a new unit. That is why there is a test button. The test button sends a charge thru the sensor that in a manner that is above my head "simulates" the presence of CO.....If the test is not successful the alarm will not sound and the display should show an error code, this will vary from on brand to the next. I am comfortable with relying upon this test method as it is solely the purpose of the test button and the unit. It is the reason that the manufacture recommends the unit be "tested" weekly or monthly. In my trailer I hit the button as I am setting up shop as a force of habit, at home I do it with the kids once a month because it promotes good safety practices.
There is what is called calibration gas, which is typically a mixture of CO and nitrogen that you can test a unit with. However I have never seen it produced for a consumer level and I am fairly certain the cost would be prohibitive.
People can use what ever method they want, but IMO if you are going to conduct a test you should at least know what the pass/fail criteria is or you are just spinning your wheels.
Both types of CO detectors in common use have a change in electrical current from the detector when the level of CO changes. The test button simulates this change in current through the alarm circuitry. It cannot test whether or not the detector is reacting (in part or at all) to the presence of CO.
Whether or not the detector/alarm produces time-averaged readings is a function of the electronics, not the detector element. The cheapest detector alarms do not time average or provide a CO concentration readout. They just alarm when the CO concentration crosses a pre-set threshold (assumes proper operation). Guess what type of CO/propane alarm my FR A-frame has. :-)
The only purpose of the CO detector/alarm is to provide early warning before CO levels reach dangerous concentrations. A false negative - rising CO levels are not detected/alarmed - can be fatal, especially with a known (assumed to be working) alarm present.
Given that CO detectors have inherently unknown but limited lifespans, and the number of electronic devices that don't work out of the box, you better believe that I'm going to verify my just-bought new detector will actually detect CO. Am I particularly concerned with whether or not the alarm set point is precisely 40ppm? No, nice to have, but not critical for the function. So long as the device responds promptly to dangerously elevated CO levels to give me early warning to get out of the house or RV, it's done its job.
I like the idea of an outside test much better than my garage test. I like even better using 2 detectors - one of which has a readout - to compare against each other when testing.
my thoughts, your choices