Cooking Safer Inside Tents

[DAN-Y]

we can NOT tell whether there is an improvement.
Without good measurements there is no provable progress.

Cheers

If you still have your Reactor do some testing this spring/summer.

[Roger Caffin]

No, I do not have it any more.
Cheers

[Rex Sanders]

Carbon Monoxide Meters

For $40 you can buy a carbon monoxide meter that weighs 3.5 ounces (100 grams) with batteries and without the metal belt clip, and measure:
• CO output of your favorite stoves
• CO output before and after stove modifications
• CO increases while using a stove in unapproved locations like well-ventilated tents and tent vestibules. This meter is light enough to take on a shakedown trip for “in-the-field” testing.

Prefer a meter from a well-known-in-USA brand? You can buy the Klein ET110 for about $100 from several sources.

What you really want to measure are CO changes after stove or tent modification, and changes over time while using a stove. You probably won’t get 1 ppm accuracy from any affordable meter, but you don’t need to.

Note that home carbon monoxide alarms are designed to respond slowly (it’s complicated), so that lighting too many birthday candles doesn’t trigger false alarms.

Again – don’t be stupid. If you see CO numbers at dangerous levels or climbing there, stop everything and get to fresh air. Most meters have settable alarm levels. Learn how to set them and use them to match your risk tolerance.

— Rex

[DAN-Y]

For $40 you can buy a carbon monoxide meter that weighs 3.5 ounces (100 grams) with batteries and without the metal belt clip, and measure:

 

quote:

Reviewed in the United States on March 19, 2022Verified Purchase
I purchased this specifically to check my furnace, which was beginning to get pitted in the heater module, which can cause CO leakage. However, for this review, I just used my car’s tailpipe to check operation.

DESIGN: This is a very ergonomically designed handheld with a nice display and good ease of use, once you decipher the chinese-english manual. It takes three AAA batteries and has a belt clip in the rear. It does have the CE approval mark on the battery cover.

RESPONSE TIME: The response time to get an accurate reading is 120 seconds. When you first turn on the unit, it begins a 120-second countdown before it goes to the main screen to let you know when the first valid reading is. This is a nice feature, and it is also nice that you can skip the delay and go straight to the reading by pressing the power button again. I think some of the people who claimed the unit didn’t detect CO may have not read the manual.

FUNCTIONALITY: It has everything you would need for a CO monitor.

— MODES: You can set it in MAX hold mode, which causes the unit to only update if a reading is higher than the last displayed reading. This is especially useful if you don’t want to wait around for an intermittent CO source to turn on. For example, you could set this on the floor next to a gas furnace and go back and check it later. There is a HOLD mode to just keep the current displayed value on-screen, such as if you wanted to record the value in a logbook. When you press the MODE button from SCAN mode, you go to HOLD mode. The MIN mode operates like the MAX mode, although I don’t think most users will have any use for it. We all want to know the MAX value, right?

— UNITS: You can read the units as PPM or umol/mol by pressing and holding the C/F button in SCAN mode. Default is PPM.

— AUTO OFF: By default, the unit remains on until you shut it off, but there is also an Auto Off mode that shuts it off after 30 minutes without a keypress. The manual is incorrect about how to change this. You need to press and hold the BACKLIGHT button while in SCAN mode, then press the button again to toggle the mode ON or OFF. Another press and hold gets you back to the main screen. A nice feature is that when it is turned on, a little clock icon will be shown on the display to let you know it is set.

– ALARM LIMIT: You can change the limit at which the unit alarms by pressing and holding the MODE button while in SCAN mode. You then use the C/F button to move the cursor to different digits, and the BACKLIGHT button to change the value. You press and hold the MODE button again once the limit is set to return to the main screen. The default is 24 PPM, and you should not change this if you are using this to monitor CO while you are sleeping. Prolonged exposure above this limit is dangerous. I think the main reason to adjust this limit is if you are using the device to obtain readings you know are high, and you don’t want the annoyance of an alarm condition. I do think the currently set limit should either always be displayed on the screen, or displayed each time the unit is powered on, since this is a safety setting. It is not, so it is a good idea to always verify the alarm threshold if you are using this for your personal protection.

— ALARM: When the set threshold is exceeded, the device will beep loudly and flash the backlight on and off. I tested this by putting the device near my tailpipe. It responded immediately with a reading above the threshold, and the CO level began to climb due to the sensor’s response time. The 2nd photo shows the alarming unit.

— C/F: The unit displays the ambient temperature in degrees Celsius or Farenheit. You can toggle between units by pressing the C/F button from any displayed mode in the main screen.

— CO UNITS: You can display the CO units in PPM or umol/mol simply by pressing and holding the C/F button. Each press and hold toggles the unit display. This is not mentioned in the manual.

— BACKLIGHT: The BACKLIGHT button ( a bulb icon) turns the green backlight on and off.

MANUAL: Poorly written by Chinese author who doesn’t know English well. Sadly, this occurs all too often with products made in China. There is some missing information, and some outright incorrect information in the description of how to use the product. I am deducting one star strictly because of the user manual, and I think it is important to have a well-written user manual, especially for a safety device. See above for the correct way to perform the various functions.

SERVICE LIFE: The manual states that the sensor is only good for three years. Be aware of this when you purchase it. If used infrequently, you may want to test it with a CO emission before relying on it for safety purposes.

[Roger Caffin]

I do have a CO meter – obviously. From long ago, but it still (seems to) work.
But what I want is one with an analog output! So I can hook it up to my data logger. Sadly, this does not seem to be common.

Cheers

[Rex Sanders]

But what I want is one with an analog output! So I can hook it up to my data logger.

One workaround I’ve used: smartphone video of the device screen, with a tripod or something similar. Add wall-power source for longer sessions. Timelapse mode can help. Good use for obsolete smartphones not yet recycled responsibly.

Then review the video to scribble down numbers, or take screenshots of rare-but-interesting events.

Often must turn off “sleep mode” on the measuring device. A feature I look for when buying new ones.

Not perfect, but frequently good enough.

— Rex

[Roger Caffin]

Hi Rex

Thinking . . .
No smart phone at all.
But I do have a Trail Camera which takes external power and can be programmed to take a photo every T seconds.
Hum . . .
Thanks for the idea.
Cheers

[Rex Sanders]

Thoughts on lowering carbon monoxide and improving canister stove efficiency.

I learned a lot while figuring out how to fix old propane wall heaters. Both the pilot light and main burner have two sources of air (oxygen). Entrained and highly mixed air and fuel from the pinhole jet inside the burner head is most important.

Air picked up by the flame itself is a relatively slow, inefficient, and incomplete process. Think of how much smoke most wood-fueled camp fires give off. And how much less gasified wood stoves give off – they convert the wood to flammable gas, mix that with more air, and then burn the result.

Too little entrained air leads to yellow flames, poor performance, and too much carbon monoxide. Proved this to myself by adjusting the right gadgets on the wall heaters to turn soot-generating yellow flames into mostly blue flames that were hotter, too.

How could this knowledge affect MSR Reactor and Windburner stove modifications?
Unfortunately, adding more air after the burner plate probably won’t improve the situation much. More air needs to be entrained and mixed with the fuel before combustion starts to reduce carbon monoxide. This almost certainly means taking the stoves apart and modifying the guts. Or maybe running them at low enough levels that they get sufficient entrained and mixed air.

Ever wondered why canister stove designs evolve so slowly?
High upfront tooling costs. I’m guessing MSR made the Reactor and Windburner changes they could without breaking the bank, then slapped on warning stickers. Or maybe designs like those just can’t work without generating lots of carbon monoxide. I am not justifying MSR’s decisions.

How could this knowledge affect DIY stove designs?
Pay a lot of attention to entrained, pre-combustion air. Measure carbon monoxide levels as you make changes. Don’t assume you, or potential customers, will always use this stove outside of a tent or other enclosed shelter.

Too much entrained air leads to noisy, jumpy blue flames that wind can blow out more easily, but doesn’t increase carbon monoxide. So part of adjusting propane wall heaters, and probably canister stove designs, is hitting that sweet spot between too much noise and too little entrained air. Which changes depending on altitude.

Which might explain noisy canister stoves that also need windscreens. Turn the flames down, and your stove will be quieter, more efficient, generate less carbon monoxide, and might not need a windscreen. But you won’t win any “2 cup boil time” contests.

— Rex

[Roger Caffin]

Hi Rex

I agree with all your comments except for the bit about windscreens.

Some burners are so badly affected by a sideways wind that the flame sits on only half of the head and the flames go sideways past the bottom of the pot, never even heating the pot. The windscreen fixes all that.

Cheers

[Rex Sanders]

Which leads us full circle. If you cook inside a tent (with enough ventilation, etc.) then you won’t need a windscreen! And you’ll save weight, too. Win-win.

Except for the part where you might die if you screw up. Be careful!

— Rex

[Jon Fong / Flat Cat Gear]

In my experience, most stoves will operate OK up to about a 2 mph wind.  At that speed, it is hard to keep a BIC lighter going.  Inside a vetible (with ventilation up high and shielded at ground level) you should be OK not using a windscreen.  That being siad, I usually hike in the Sierras (black bear) and have to set up the kitchen far from my tent.  My 2 cents.

[Roger Caffin]

The other advantage of a reasonably close-fitting windshield is that it focuses the hot air around the walls of the pot, thereby increasing the efficiency and reducing the fuel use.

Cheers

[Rex Sanders]

More notes from my propane wall heater tinkering:

To achieve the holy grail of quiet blue flames, you can make three changes:
– More or less air
– More or less fuel
– Better fuel-air mixing

Examples:

– The pilot lights I worked on have fixed intakes for pre-combustion air. Other than cleaning them of soot and dirt, not much to change there. But there is a screw on the gas valve to adjust the fuel flow and get a quiet blue flame.

– The main burners n had fixed fuel flows and a rotating plate to adjust pre-combustion air. Twist the plate until you get as close as you can to the holy grail.

– I could change air-fuel mixing by swapping fuel jet orifices to compensate for altitude. Didn‘t try that, way beyond my pay grade to explain.

For future fire-from-DIY-canister-stove geeks (not me), keep these principles in mind.

Maybe someone could invent a Bluetooth-enabled stove with a subscription-based app that automatically swaps stove orifices, and adjusts fuel and air flows, depending on wind and barometric pressure, to achieve peak performance and quieter operation in more conditions.

Count me out.

Besides Roger, who knew canister stove design and engineering was so complex!

— Rex

[Roger Caffin]

Bluetooth-enabled stove
Love it!
Tent on glacier in storm explodes, due to internet hackers . . .

Cheers

[Robert W]

Fantastic article!  Thank you for doing very controlled tests. Then  digging to the next step to try to understand unusual results.  Very useful on an important topic.
Happy Camping

[DriCamp]

Hilariously written, my compliments to the word chef.

[Author]

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