Proposal for stove tests: Use 32F or 0 c water

Air temperature also would need to be consistant and "no wind". However, wind will affect some more than others so it is impossible to get all the variables out though it is a good goal.

Agreed, air temp and wind speed are critical but especially wind is almost impossible for the layman to accurately control, measure, and repeat.

I just thought that using off-freezing water would be one thing that is easy to replicate anywhere in the world without any tools.

Hi James,

Trying to get a standard for stove backpacking stove testing is like beating your head against a brick wall, I tried it some time ago and my head still hurts.

We all have a different idea on how it should be done.

What I do is not worry about the starting temperature but more about the finish temperature as water boiling temperature can vary with altitude/ atmospheric pressure changes (about 3ºC per 1000 meters) and water purity, when I do my tests I start with what ever the start temperature of the water is and I stop them at 95ºC, I then extrapolate the results to cover a temperature rise of 80ºC.

There are several other factors that have an influence on stove performance.

To get a trustworthy result all tests should be repeated at least three time and the results averaged, and do not be surprised if the tests have different results even if the test conditions are exactly the same.

Tony

Stopping at 95c is good. Since I'll be camping mostly at around 10,000 feet/ 3000 meters my concern is bringing cold water up to a boil at 90c.

One thing I noticed with my digital thermometer is that it can't quite keep up with the very rapid temperature rise of the Jetboil. I have 10 seconds of rolling boil before the thermo passes 210 F. Obviously a quicker thermometer would be better.

The critical number for me was to know how much fuel to bring 3 cups of water to just shy of boil. I found 6 to 7 grams each time over 4 tests.

> I have 10 seconds of rolling boil before the thermo passes 210 F
IF (IF) you are doing this at sea level, then maybe trust the thermometer a bit more. The earlier 'rolling boil' may well be the dissolved oxygen in the water coming off. It looks just like 'boiling', really!

The very fast Jetboil times originally quoted are rumoured to have been for taking water at 30 C up to the start of this psuedo-boil, around 90 C. I cannot certify that this is so, but that's what I was told by someone who knew what was going on.

Cheers
Roger

Hi James

"One thing I noticed with my digital thermometer is that it can't quite keep up with the very rapid temperature rise of the Jetboil. I have 10 seconds of rolling boil before the thermo passes 210 F. Obviously a quicker thermometer would be better."

Your Digital thermometer's 10s delay in reading the temperature is most probably due to the slow response of your thermometer probe, all probes have a response time and it is much slower in air than water. To protect the actual measuring part most probes are encased in a Stainless Steel casing, this has to change temperature before the actual measuring tip can therefore slowing down the measuring process. Check your thermometers data specifications, it should tell you what the response time is.

There are three main types of probes for digital thermometers, thermocouples TC (most common and cheap), Platinum resistance Thermometers PRT and thermistors.

I use a home made thermistor probe with a 300ms response time in water, at work I have some that have a 7 ms response time but they are very delicate and expensive. I have one calibration thermistor probe that cost A$3500 (probe only). Thermistors need some not so common electronics, I was lucky as my work disposed of some thermistor bridges that I have repaired and modified to suit my needs.

Thermocouples which are the most common come in different size and temperature ratings. the most common is the K type. Faster response thermocouples can be purchased from Omega engineering http://www.omega.com/ with some basic electronic knowledge they could be adapted to suit your digital readout.

Tony

James,
Check the ThermoWorks.com site and look at the ThermaPen.
It's a kitchen thermometer with a 4 second response.
$90.

Great if you don't need to drive a data logger.