Testing New LP / CO Detector

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

Great Horned Owl

Well-known member
Joined
Feb 10, 2012
Posts
1,815
Location
Lake County, Illinois
I just replaced my LP / CO detector which had reached the end of life condition. After completing the installation, I decided to test it. An unlit propane torch set it off in about 5 seconds, so that function works fine.

The CO function is not so easy. I have everything closed up. The oven and three stove burners have been going full on for about an hour. So far, nothing.
any thoughts?

Joel
 
You're not going to produce CO until the oxygen is at a low level. Chances are the oven and burners are sucking in plenty of air. I work for a gas detection company. Oxygen and CO cell sensors usually never have a problem. It's the methane that takes a beating. You can also take the unit out and go to a gas supplier. I'm sure they would be happy to give your detector a blast from a tank. Some fire departments also have small tanks of CO to do the test.
 
Thanks. I also tried turning on a ventless heater, but still no alarm, after 3 hours. With the previous detector, the heater alone was enough to trigger an alarm, but only above around 7,000 ft., which would have been a low oxygen situation.

What prompted me to test it is that id did not go through the proper startup sequence. The manual states that when first powered up, the LP LED will blink green, every 8 seconds, for 3 minutes. In this case, it blinked red every second, for about 5 minutes. I wasn't thinking that the CO cell might be bad, but rather, the surrounding circuitry.

A call to the manufacturer (Atwood) produced "Don't worry about it. It's probably OK."  Somehow, that response, coupled with her apparent lack of knowledge about the detector, didn't seem very reassuring.

Joel
 
When I was reading up on LP detectors to see if I need to replace the one I've got, I believe I read that you should not test the newer ones.  I guess testing them with propane or butane uses them up or something.  I'll try to find a reference, if you'd like.
 
richardhufford said:
When I was reading up on LP detectors to see if I need to replace the one I've got, I believe I read that you should not test the newer ones.

Yes, that's true. This is what I do for a living. This is how it works.

Propane ignites at around 850 degrees Fahrenheit. Picture a little oven the size of a small thimble. Inside is either a platinum or palladium wire wound in a coil that requires a microscope to see. Every once in a while you heat your little oven up to 1,000 and measure how much power it takes to get to that temp. If it takes less power to maintain 1,000 you know gas is present because it's helping heat your little oven. Spraying propane on your sensor will cause it to go off the charts hot hot hot. That's why they don't want you to test it. These filaments can only last so long heating up and cooling down. That's why they have a lifespan. Some as low as 2 years.

If anyone is interested I'll post a pic in the morning when I'm at work. Not sure I can take a pic through the microscope but I can at least hold a filament in my hand.
 
I should mention. Don't worry about your detector. They go through a self calibration test every so often. There is an oxygen sensor in there also and temp sensor so they can calculate the resistance at absolute zero degrees. At absolute zero wire has no resistance. Your detector will adjust itself and over time it will require more and more power to heat up the filament. When it reaches a certain point it will stop working and beep non stop. 
 
I just downloaded and read a manual for the Safe-T-Alert model 70-742-R-KIT-BR detector, and I swear that a year or so ago it said never to test the unit using propane or butane.  Today, though, the manual says "You may use propane or butane gas to test the gas sensor".  I guess you can ignore my comment above!
 
I decided to solve the problem by returning the detector, and getting a new one. The new one behaves exactly the same as the other one did. I am beginning to suspect that the detectors are working properly, but the manual is screwed up.

Just to be on the safe side, I ordered a spray can of CO gas to test it.

Joel
 
Back
Top Bottom