[pct-l] Isobutane Canister performance

[Dan Welch]

Mary,

I think anecdotal results have merit - especially when they largely jive with "lab test" results that have been conducted by others.  Roger Caffin and Will Rietveld of BackPacking Lite have published a number of articles on canister stoves and their efficiencies (including comparisons to alcohol stoves.)  Their testing is mostly under strictly controlled test conditions - so strictly controlled that they gave me pause.  As backpackers we don't operate under controlled conditions - but lab tests can still give good guidance for making decisions.  I just am much more comfortable when anecdotal evidence corroborates lab tests.  So thanks for sharing your results.  

Anyway, BPL has tested a number of canister stove rigs under different wind and temperature conditions.  Under calm conditions, they found a range of 10-15 gms fuel per L "boiled" (see their definition and partial test description below.  The article gives much more detail.) They too were using MSR cartridges and their findings can be reconciled with your finding of 6.1 gms fuel for 1 and 3/4 cup (equal to 14.7 gms per L.)  

That was for clam conditions.  They found that wind degraded this efficiency greatly.  In a 12 mph steady, controlled, wind, fuel use almost doubled.  But, consider that a 12 mph STEADY wind is pretty unusual AT GROUND LEVEL.  In this type of condition most people would be seeking a more sheltered spot for cooking, so I consider this extreme.  A good test for "worst case" conditions, but not something to judge fuel use by.   Importantly, adding a windscreen recovered most of this lost efficiency.

Notably, the JetBoil systems had the best efficiencies in calm conditions (~10 gms per L boiled) and the FUEL USE WAS LARGELY UNAFFECTED BY WIND. These articles are the reason I purchased a JetBoil.  The efficiency and lack of wind effect on the JetBoil has been borne out by my field tests (conducted in 3-season Smokies Mtns. conditions and Summer in the Sierras & Rockies high country.)  However, my records are nowhere near as "scientific" as the lab studies - but they are applicable in their own real-world way. 

Thanks again,
Timberline


Excerpt from Will Rietveld article (subscription required):
http://www.backpackinglight.com/cgi-bin/backpackinglight/lightweight_canister_stoves_test_report.html#.UjCcaczD_IU
"Tests were conducted at 6,650 feet (2,027 m) elevation. A 1.5-liter MSR titanium pot 6 inches (15 cm) in diameter was used for all of the tests, except for the Jetboil stove, which has its own pot. The pot and stove were cooled between test runs. Boiling was measured with a signaling digital thermometer at 199 °F (93 °C, the boiling temperature at 6,650 feet elevation is 201 °F; we measured at 199 °F to avoid the vaporization process) with the temperature sensor placed in the same position each time. Each test was repeated three times."