QuietStove.com

Monday, August 29, 2011

Fastest Boil Time?

So, which stove has the fastest boil time? Or does it even matter?

If you read my reviews, you'll notice that I don't normally list boil times. Why do you suppose that might be?

First, how important is it? Something in the neighborhood of 5 to 7 minutes to boil a liter is fine in my book. Waiting another 30 seconds or so for a boil makes no real difference to me. Now, if it were another 3 minutes, maybe then I'd worry about it, but half a minute either way isn't going to really affect how I cook or how I organize my time while backpacking. After all, isn't one of the reasons we go backpacking to get away from all of the arbitrary time pressures of "civilization?"

Second, don't forget the number one rule of stove fuel economy:
1. Turn it down! High heat = inefficient = wasted fuel.
2. Use a lid. Escaping steam = escaping heat = wasted fuel.
3. Use a windscreen. No windscreen = dispersed heat = wasted fuel.

Running a stove on high burns through more fuel than you really need; you can accomplish the same with less fuel if you just run it on a low to moderate flame. You are carrying that fuel on your aching back, aren't you? Shoot! Conserve it. Why worry about shaving 30 seconds off a boil when the price is to carry more fuel?

Third, how helpful is a boil time in comparing one stove to another? There are no standards for boil times. If there were a standard (e.g. 1 liter of water at 45F/7C, 5mph/8kph wind, plain aluminum pot with lid, 1 atmosphere pressure), then we could compare boil times stove to stove and perhaps have something meaningful. But there is no standard, so one stove company may be boiling water that is 45F/7C outdoors whereas another company may be boiling water that is 75F/24C in a windless laboratory. That's like comparing a diesel truck to a skateboard. One stove manufacturer may have its facility in Denver, Colorado (elevation about 5000'/1500m) whereas another may have its facility in Chicago, Illinois (elevation about 600'/180m). Comparison of boil times from those two locations isn't even close to relevant.

So, to my point of view, a boil time doesn't figure prominently as I evaluate a stove. Sure, it has to be within reason, but even 60 seconds either way wouldn't have any significant effect on my enjoyment of the outdoors. Not only that, if I start focusing on maximizing my boil times, I'm just burning through fuel -- fuel that I have to pack. And finally, since there is no set of standard conditions for boil times, they're of little use for comparing one stove to another. Don't forget that boil times vary even on the same stove. If one boil takes 4:45, 5:15 the next, 4:35 the next time, and then 5:05 on the boil after that, a stove company will probably pick the single fastest time and list that as their official boil time. Singularly useless.

To me at least, boil times are just the "macho" claims of stove advertisers. Within reason, boil times aren't really important to a guy sitting by a beautiful alpine lake trying to get away for a while. So, don't sweat the boil time. Look at how you cook, what you cook, and under what conditions you cook. How a stove serves you in the context of how you do things in the outdoors is going to matter a whole lot more than 30 seconds off your boil time.

HJ

Thursday, August 25, 2011

Stove of the Week: Hank Roberts Mini Stove, Mark III

I happen to like my old Hank Roberts stove, a stove that dates back to the 1960's. It's in very nice condition. I have the Mark III version.

So compact! And inside, the original accoutrements that came with the package.

Unfortunately, it's been some years since either the stove or its proprietary fuel canisters have been produced (see The Hank Roberts Stove -- With a Proper Canister for information on and photos of the original canister type).  Therefore, to the original contents, I add a few "essentials," all of which are easily contained within the outer shell of the stove.
Now, you probably recognize the Bic type lighter, but what of the other items?

Well, let's take a look.

The silver colored cylinder is an adapter made by Henrik from Denmark who I met on an internet forum.  Unfortunately, I've lost touch with Henrik.  :(

The hose is a spare gas hose to a Chinese made stove that I bought on eBay. The hose screws into the threaded end of the adapter, like so:

Now, let's take a look at the stove itself. That little discus you saw earlier? Here's what it looks like assembled. Pure genius.

Here's the valve assembly.
Do you see that brass "needle" to the right? That needle fits into a "rosebud" on a proprietary canister. Such canisters are alas no longer made.

Here's where Henrik's adapter comes in.
 The adapter slips over the needle.

And voila! here we are ready to cook.

Did someone say "cook?" Now, where would we be without some flame shots?

A very nice, efficient blue flame.

The Hank Roberts Mini Stove (Mark III) really has a good strong flame.

The original proprietary canisters contained a wick. The wick conducted liquefied gas into the burner. Liquid did you say? Why then we ought to be able to invert the canister and be able to run the stove in liquid feed mode. Indeed, we can do just that.

Be sure to let the stove warm up before inverting the canister. If you don't let the stove warm up a bit first, the stove will flare.  Running a gas stove in liquid feed mode allows one to operate a gas stove in much colder temperatures than in conventional upright (vapor feed) mode.

As they say, "the proof of the pudding is in the eating," so it's time for the "tea test."  Handily passed.

And if tea test, then tea.
Delicious, I assure you.

I thank you all for joining me on another Adventure In Stoving,

HJ

The Hank Roberts Mini Stove (Mark III version)
What's good about it?
Compact
Capable of operation in colder weather than conventional (upright) gas stoves
Highly adjustable flame
Good, strong flame
Stable because of nice wide base
Good pot stability because of well designed windscreen/pot support
Some wind protection from windscreen (it really needs a separate windscreen in a stronger wind)

What's bad about it?
Canisters are no longer available (but can be operated with an adapter, if you can get one)
A little heavy (about 8 oz) by modern gas stove standards
No longer available in stores (but available on eBay and such)

Hank Roberts Mini Stove:  Highly Recommended (considering its era).


Hank Roberts Stove -- Related Blog Posts

Tuesday, August 16, 2011

What's the Best Alcohol for Stove Fuel?

A lot of people interested in going light are trying alcohol as a fuel.  But if you head down to the store, you'll see all kinds of alcohol.  Which alcohols are good choices for stove fuel?  Which ones are poor choices?

Alcohol as a Stove Fuel (in order of best fuel to worst fuel)  The best alcohol fuel is ethanol (ethyl alcohol).  It has the highest number of calories per gram* of any stove fuel suitable alcohol (I really don't consider dirty-burning isopropanol to be suitable as a stove fuel) and burns reasonably cleanly.  If you can get lab grade "absolute" (200 proof) ethanol or 190 proof liquor, that's going to work really well, but both of those (lab grade absolute ethanol or 190 proof "drinking" alcohol) are pretty expensive -- if you can even get them.  Lab grade absolute ethanol is often restricted as to whom can purchase it (i.e. not the general public), and many locations prohibit the sale of high proof drinking alcohol.  Check the Materials Safety Data Sheet (MSDS) on lab grade absolute ethanol which may contain benzene which is toxic.

Another option is "denatured" alcohol which should consist primarily of ethanol.  The problem in the US is that there are no standards for what constitutes denatured alcohol.  In fact, some denatured alcohols in the US are less than 50% ethanol.  In addition sometimes nasty stuff is used to denature the alcohol (render it undrinkable), stuff like methyl ethyl ketone, whose fumes you don't really want to breathe.  "Green" denatured alcohol generally has a much higher ethanol content and a lower "nasty stuff" content.  Check the MSDS.  The higher the ethanol content, the better it is for use as a fuel.  Because higher ethanol content alcohol burns hotter, sometimes the burning will "get ahead of itself," and you'll get some soot.  If the stove is overheating and producing soot, try adding water to the fuel (after you get into your camp site; don't carry it!). Adding water will calm down the burning, allowing the alcohol to mix properly with air and burn cleanly.  Try adding a little water at first, and then add more water as needed to eliminate any soot (up to 25% of the total volume).
"Green" denatured alcohol generally has the highest ethanol content.

Outside the US, there is a particular variety of denatured alcohol sometimes available, methylated spirits.  Methylated spirits is ethanol with methanol used as a denaturing agent.  Methylated spirits is often called "meths" or "metho".   Methylated spirits makes an excellent stove fuel.  Would that it were available in the US.

Methanol (methyl alcohol) is another popular fuel alcohol, frequently bought in the yellow HEET bottle because HEET is so widely available (at least in the US).  You do have to carry a bit more methanol to do the same amount of cooking since methanol contains fewer calories per gram* than ethanol.  Methanol fumes are toxic, and methanol absorbed through the skin is toxic.  How toxic?  If you're cooking out doors, I don't think fumes will be too bad if you're observant of wind direction and position yourself accordingly.   I don't have a way to state a safe limit for skin absorption, but handling with care should be enough.  It's not like you hear about a lot of through hikers on the Appalachian Trail (AT), where yellow HEET is easy to get and very popular, getting stricken with methanol poisoning.   Methanol has a higher vapor pressure than ethanol and works better than ethanol in cold weather.  I can't comment a lot on methanol performance in cold weather because I typically bring a gas or liquid petroleum fueled stove for cold weather.  Conversely, methanol can have "runaway thermal feedback" in hotter weather.  "Runaway thermal feedback" basically occurs when the alcohol gets so hot that it boils really violently and doesn't burn efficiently.  Adding water (see remarks above) can help calm down a burn so that the alcohol can burn more cleanly.

Yellow HEET is methanol.
Red HEET (Iso-HEET) is Isopropanol

LAST choice is isopropanol (isopropyl alcohol).  Isopropanol is easy to find at most any drug store (typically called rubbing alcohol), but it's usually a sooty mess to burn.  Even though Isopropanol has the highest heat content per gram*, it is really not suitable as a stove fuel because it's such a mess to burn.  Isopropanol is toxic in terms of both fumes and in skin absorption.   Red HEET (i.e. Iso-HEET) is isopropanol. Not recommended.

With any alcohol fuel, your flame velocity is going to be fairly low (think candle as opposed to blow torch).  Therefore, an effective wind screen is really essential for an alcohol stove.

SUMMARY
The best choices for fuel for an alcohol stove are:
1.  Lab grade absolute ethanol (200 proof) or high proof liquor (190 proof).  High heat content per gram (relative to methanol), relatively clean burning, and generally non toxic, but check the MSDS on lab grade absolute ethanol which may contain benzene which is toxic.  A good choice for warmer weather.
2.  "Green" denatured alcohol in the US or methylated spirits (ethanol with methanol used as a denaturing agent) outside the US.  Methylated spirits is often called "meths" or "metho".  Good heat content, relatively clean burning, fairly non-toxic depending on the amount and type of the denaturing agent.  In the US, always check the MSDS.  A good choice for warmer weather.
3.  Methanol, for example yellow HEET.  Decent heat content, very clean burning, but definitely toxic in terms of fumes and skin absorption.  Reasonably safe if used with care.  A good choice for colder weather.
4.  You can use Isopropanol, for example red HEET (Iso-HEET), but it is not really suitable as a stove fuel because it's generally a sooty mess when it burns.  Highest heat content, but dirty burning, and definitely toxic.  Not recommended.

Finally:   Drinking anything not intended for human is pretty much a bad idea, but if you're going to do such a thing, always check the MSDS before you drink anything not intended for human consumption.

HJ

*Heat Content of Alcohols
Fuel          MJ/kg     MJ/l 
Methanol      19.930    15.78
Ethanol       28.865    22.77
Isopropanol   30.447    23.93


Related posts and articles:

Thursday, August 4, 2011

New Stoves from MSR

It looks like MSR is putting out three, count 'em, three new stoves.


UPDATED 9/6/2011 See also this related post which contains videos of the new MSR Whisperlite Universal.

UPDATED 10/4/2011I have written a review of the MSR Whisperlite Universal.


The first is the MicroRocket.


Basically, the MicroRocket looks like it's just a lighter version of the PocketRocket, but with some minor improvements. In particular, the pot supports are shorter and supposedly (per MSR) stronger, which would go a long way toward correcting the PocketRocket's Achilles heel.  Reportedly, the MicroRocket will be 15% lighter than the PocketRocket which would mean that the MicroRocket would weigh about 2.5 oz.  A German press release I saw lists the weight at 75g which would be 2.6 oz.  Either way, it's a very nice, light stove.
An MSR PocketRocket (left) and an MSR MicroRocket (right)


MSR MicroRocket (left) and MSR PocketRocket (Right)

A second "improvement" is the addition of a separate piezoelectric starter (see first photo). The starter is a stand alone unit not built into the stove. I'm not quite sure about the utility of this. Why not just bring matches, a lighter, or a firesteel?  Matches, a lighter, or a firesteel seem like they'd be a lot more versatile. With matches, a lighter, or a firesteel, one can light a variety of fires, not just a stove.  I haven't seen MSR's piezoelectric starter, but I think a piezoelectric starter would only work on a stove.  It'll be interesting to see if their separate piezoelectric starter catches on.

The pot supports on the new MicroRocket fold up a bit differently and the valve control folds over the body of the stove.  It all collapses down into what looks to be a very compact package indeed.
An MSR MicroRocket folded (left) and piezoelectric ignition (right)

The new case for the MicroRocket looks more compact overall when compared to the case for the PocketRocket.
Left to right:  Folded MSR MicroRocket, piezoelectric ignigtion, a MicroRocket case, and a PocketRocket case

Here's Steve Grimes of MSR discussing the new MicroRocket:



The second new stove is the Whisperlite Universal which is a "hybrid" stove (MSR's words) that will burn both liquid fuel and gas.






Apparently the Universal is a Whisperlite Internationale with significant revisions. Gone are the wire legs, and the generator has been significantly revised. Note also the black plastic canister stand which holds the canister upside down. It appears that MSR is finally conceding that their remote canister stoves work with the canister inverted (i.e. liquid feed), a fact that they have mysteriously downplayed for years. It's a wonder that MSR wouldn't market the heck out of the fact that their remote canister stoves can operate with the canister inverted since an inverted canister stove can operate in temperatures at least 20 degrees Fahrenheit (about 10 degrees Celsius) colder than conventional upright canister stoves. The Whisperlite Universal supposedly has multiple connectors that can be swapped out for use with gas or liquid fuel. The Whisperlite Universal comes with three jets (much like a Primus Omnifuel) for use with differing fuels.

A closer look at the burner of the MSR Whisperlite Universal

From what I can see so far, this new Whisperlite should be a very interesting stove capable of a wide variety of modes: upright (vapor feed) gas, inverted (liquid feed) gas, and liquid fuel (white gasoline or kerosene). Let's hope that they have not only added a new fuel to the old Internationale's repertoire but also increased the Internationale's reliability with kerosene.  If in fact the Whisperlite Universal does have increased reliability with kerosene, the Universal might indeed be a really good choice for the world traveler, particularly if the Universal were more accessible from a price perspective.  Stoves currently on the market that burn gas, white gasoline, and kerosene tend to be pretty expensive.

The new Whisperlite Universal seems to have an upgraded fuel line.  The fuel line on newer MSR stoves like the Simmerlite and Windpro is thinner and more flexible, making the stove easier to pack.  It looks like the Whisperlite has now also been upgraded to the new more flexible fuel line.  Assuming the new fuel line is just as reliable as the old one, the more flexible fuel line is a change I heartily applaud.

It's possible, but I don't know this for a fact, that the new Whisperlite Universal will be a lighter stove than either the regular Whisperlite or the Whisperlite Internationale.  I say this just based on the legs and the overall look of the stove.  Of course, any weight shed on the legs may be regained depending on how they do the connectors.  Assuming that the new Whisperlite Universal uses the standard MSR duraseal pump (look at the photo below; notice the duraseal pump in her hand), there will have to be some kind adapter that the fuel hose will plug into so that a either a standard pump or gas canister can be attached.
MSR is smart, they have made the Whisperlite Universal so one doesn't have to carry the canister stand in warm weather, when you really don't need to invert the canister.
 The canister stand of an MSR Whisperlite Universal

Here's a video on the Whisperlite Universal:




Lastly, the third "new" stove:  The Windpro II.  MSR has improved the Windpro by adding a rotating coupler and including a canister stand that holds the canister in inverted position.  Again, it looks as though MSR is finally publicly acknowledging that their remote canister stoves can be used in inverted canister mode (liquid feed).  It's interesting to me that it took them this long to acknowledge what has been there all along.  They spent a lot of money on the Reactor, which they push as a high end mountaineering stove, when they had a gas stove that would work in much colder conditions way before anyone even thought of the Reactor.

Here are a couple of photos of the new, improved Windpro II.  In the first photo, note the MSR Whisperlite Universal in the background which appears to use the same canister stand.


Here's a video on the Windpro II



I don't have any photos, but per a press release dated July 18 from Cascade Designs, apparently MSR has also upgraded the Whisperlite Internationale if I'm reading things correctly, so it looks as though there will be three versions of the Whisperlite sold:
The regular Whisperlite
The Whisperlite Internationale (Improved Version)
The Whisperlite Universal
Perhaps no changes are being made to the regular Whisperlite?

All of the new stoves should be available in January 2012.

HJ

Monday, August 1, 2011

Windscreens

In my recent article in Seattle Backpackers Magazine (Aug 2, 2011 edition), I mentioned what my preference is in terms of a windscreen for an upright canister stove (well, at least for trips where weight isn't super critical).  Something like the below (keep reading if this looks too heavy; more ideas follow):

This is a self standing windscreen made by Olicamp.

I discuss my preferred windscreen set up in my article, and I'll go into some more detail later on in this blog post, but for now I'd like to discuss some of the alternatives that are out there.  Before you look at these alternative windscreens, you should carefully read my article and all of the safety warnings in the article.  Using a windscreen with a canister stove can be very dangerous.  Make sure that you monitor the temperature of the canister frequently with your hand.  If the canister feels hot, it is hot:  Take immediate steps to cool the canister.  DO NOT EVER LET THE GAS CANISTER OF YOUR STOVE GET HOT*.

That said, let's look at some of the options out there for windscreens for an upright canister stove:

One particularly ingenious light weight idea is Jim Wood's Kite Screen.
Photo courtesy of Jim Wood
The kite screen has an excellent reputation and is definitely a workable solution to the wind challenge. For me personally, the kite screen is a bit more set up than I like to mess with, but many people really like it. By the way, if you haven't checked out Jim's site, it's worth a look.  Lot's of valuable information.  Recommended.

Another option is construct your radiation shield such that it has a lip around the edge, like so:

 You can then use that lip to put a windscreen in place like so:
Advantages:
  • The canister is fully vented making it very unlikely that you'll overheat the canister.
  • Since the windscreen doesn't need to reach all the way to the ground, a shorter windscreen can be used.
Disadvantages:
  • It's a little hard to secure the windscreen on top of the radiation shield.  Wind tends to knock the windscreen around.  However, I've seen lots of examples of clever clips and other means to secure the windscreen in place.  This is definitely something worth experimenting with.
  • The lip on the radiation shield tends to get bent up when in my pack.  A completely flat radiation shield is easier to pack.
  • Because there is such a tight mating of the windscreen and radiation shield, it's going to get really hot inside the windscreen.  Plastic or other sensitive parts like piezoelectric ignition systems could get damaged.
  • Because the radiation shield needs to securely support the windscreen, you'll need to use a little bit heavier material for the radiation shield than you otherwise would.
  • Since the valve control is inside the windscreen, you have to lift or open the windscreen to adjust the flame.  If you're just boiling water, who cares?  Just turn the stove on and let the danged thing boil.  But if you're simmering, you may need to adjust the flame.  A huge deal?  No.  Inconvenient?  Yes.

Another option is to take a titanium bowl and cut slots and holes in the bottom of the bowl such that the burner and pot supports protrude through the bottom of the bowl.
Photo courtesy of Denis Hazelwood
With a pot in place:
Photo courtesy of Denis Hazelwood


I think the bowl idea has a lot of merit.  Of course you have to sacrifice a titanium bowl, and it takes a bit of skill to make cuts that don't look really amateurish. The bowl in the photo was made by Denis Hazelwood.

Finally, there's always my preference:
This self standing windscreen consists of a series of stiff aluminum plates with wire rods that act as hinges.  This type of windscreen has several advantages:
1.  It's self standing.
2.  It's heavy enough that the slightest breeze doesn't knock it over
3.  It's tall enough that it can handle larger canisters and larger stoves.  The canister in the photo is a 220g Snow Peak canister, and the stove is an MSR Superfly, a relatively tall stove.
4.  It's very fast to set up (seconds)
5.  The rods that act as hinges can be pushed into the ground to help secure the windscreen.

BUT this type has a significant disadvantage:  it's heavy, weighing in at 201g (7 ounces) which is about the weight of a 110g sized fuel canister (when full)!

For a lighter windscreen that works along the same lines, simply replace the above windscreen with a windscreen made from multiple sheets of household aluminum foil, folded at the edges such that the windscreen stays together, like this:
The above windscreen is significantly lighter, but far more subject to being knocked around or blown over by wind.  You'll probably need to brace the windscreen with rocks and such.  The above windscreen is also significantly less durable.  But it does work.


So there's a very brief survey of some of common windscreen set ups that I've seen for upright canister stoves
1.  Self Standing
2.  The Kite Screen
3.  Windscreen mounted on radiation shield
4.  Windscreen made out of a bowl or similar item

For any of the common windscreen set ups, your imagination is the only limit to the types of materials that you might use.  Items such as pie tins, 36 ga. aluminum tooling fool, baking pans, catering dish lids, titanium bowls, household aluminum foil, roof flashing, etc. are all fair game.  Just remember:  DO NOT EVER LET THE GAS CANISTER OF YOUR STOVE GET HOT*.


With that in mind, get out there and use your stove for what it is intended for:  Good eats!!


HJ

*Letting the canister get some heat in cold weather isn't a bad idea; it will improve performance. You still need to monitor the canister's temperature even in cold weather. Even when it's cold out, that canister must never be allowed to get so hot that you can't comfortably touch it with your bare hand.  I'm talking about "normal" hands here.  Be careful if your hands are really cold.  Really cold hands may not give you enough sensation to tell how hot that canister really is.  Let your hand rest on the canister a while.  If the canister is really hot, you'll know it soon enough!  My point is that a quick touch with cold hands may not be enough.  Check the canister.