Time for a new one. Typically, CO detectors are good for 5-7 years (apparently the sensor wears out). Somewhere in the manual or on the casing it will tell you when to replace it.
Mine's been sealed up in an airtight bag w/o batteries. There is nothing that produces CO at my place unless we're off grid...unless, like li-ons, they just die whether used or not...
There are 3 basic types of CO monitor constructions:now that's an interesting question. My "new" CO detector claims to have a timer on it, but I assume it only tracks power-on hours. I've been doing a bit of searching, but I haven't been able to find if it's simply time since manufacture or power-on hours that controls sensor-life.
I did see some sites that recommended using a test-kit to check the sensor performance monthly, but I don't recall ever seeing a CO test kit.
- MOS Metal Oxide Semiconductor (the worst of the bunch. Undependable. Inconsistent readings and notification). These use a tin dioxide sensor that doesn't work very well. If you're interested, there are independent test results available for online digging showing how bad these are.
- Biometric/Colorimetric: these use a gel packet that absorbs CO and darkens. In the continued presence of higher levels of CO, the gel packet stays dark and triggers the alarm. Package it however you will, that gel packet becomes useless in time.
- electro chemical sensor: these are the most dependable, and potentially, also the most accurate. Due to the 'chemical' part of electrochemical, these sensors also wear out in time. Maybe keeping them in a vacuum might prolong their life? I don't know.
I've been using low level CO monitors for some time and they just might have saved my butt from problems once, so I continue to spend the money on them.
Here's the story.
I was prepping my car for a car nut holiday weekend. 5 days of car nuts hanging out, cruising and engaging in performance activities like drag racing, autocrossing and road racing at the 3 tracks near the event. I was in a rush and was trying to finish putting on the front 355mm Stoptech brake kit, plus new rear rotors and swap out all the lines and pads, then flush the brake fluid with ATE SuperBlue.
I was working through the night as I was supposed to leave the next day with a buddy who was also going to the event. I was working in the garage with the garage door shut because it was windy and dust kept getting blown in my eyes. Well, after completing each corner of the car, I would flush the lines, then check for leaks by starting the car up and stomping on the pedal as hard as I could before shutting her down and checking for leaks. Each time, I didn't think the engine ran for much more than 30 seconds. I should have known better about the dangers of CO (and I DID know how dangerous CO is), but I thought because I was only running the engine for a short while each time, that I'd be OK.
Due to frozen bolts etc. it was taking 1-2 hours per corner working solo. I figured this was enough for what little CO was released to dissipate. Well, by the time I finished the 3rd corner, it was now ~6 a.m. and I had quite a bad headache from pulling the all-nighter working on the car (or so I thought), but I figured, 1 more corner to go. By the time I finished the last corner and made sure there were no leaks, I had a splitting headache, blurred vision and was feeling nauseous. All classic symptoms of CO poisoning, but in my delusional state, I pawned it off as sleep deprivation.
I staggered into the house, washed up and collapsed into bed on the opposite side of the house. 3 hours later, I finally roused to a beeping sound. I have no idea how long the low level CO monitor had been beeping because I vaguely recall not understanding what the sound was and having a difficult time waking up. When I finally did wake up and determine what was beeping, I checked the monitor and IIRC, it read somewhere around 70-120ppm, then it finally hit me. In the closed garage, the CO simply built up each time I ran the car, and never went anywhere. 3 hours later, it had made it from the attached garage all the way across the house to the bedroom.
If I'd had any real sense, I should have stumbled out of the house and called an ambulance. My vision was still blurry, my head was still splitting and I was extremely dizzy and nauseous. Instead, I threw open the nearest window and took several deep breaths, then proceeded to open all the windows in the house, then lay on the couch with a fan placed in the window sucking in air from outside and blowing right on me.
This was how my buddy found me, when he showed up at 12 (when we were supposed to leave). We didn't leave till after 6pm when I finally felt OK enough to get up.
Fortunately for me, I apparently didn't suffer any long term effects from that incident. If I'd brought the CO detector with me into the garage, it wouldn't have happened in the first place (or if I'd been smart enough to open the garage door to vent the exhaust for a short time during and after running the engine).
I always make sure I have one of these low level CO monitors now, and the great thing is, you can use a match to check their operation if you want to.
http://www.inspectortools.com/CO-Experts-Model-2014-CO-Low-Level-Monitor-p/ke2014co.htm
I take it traveling too, after reading an account of vacationers who were smothered in their beds because the pool heater in their hotel malfunctioned.
Max
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