Butane Adapter WARNING

A butane adapter can be a nice thing to have.  I mean, if the weather's warm, why not just use cheap 100% butane canisters with your backpacking stove?  Cheap 227g butane canisters are available for about $1.25 at the cheaper stores whereas backpacking canisters usually sell for about $6.00 for the same amount of fuel.

There is however a butane adapter being sold that can be really DANGEROUS if you don't know what you're doing.

I've seen a few different colors, but most are black and look something like the below.

A butane adapter -- POTENTIALLY DANGEROUS

These adapters allow one to mate a cheap 100% butane canister with a standard threaded backpacking stove.

A cheap 100% butane canister of the type frequently used in restaurants for table side cooking

These butane adapters have a protruding "lug" on them.  THIS LUG IS IMPORTANT.

The lug on this adapter can be seen near the top of the photo.

The lug must remain pointed up whenever a stove is in operation.  Let me explain why and what happens if you mess this up.  The lug fits into a gap on the collar of the butane canister.

A butane canister (left) has a notch that the lug on the adapter (right) fits into

OK, let's hook the adapter to a backpacking stove's fuel hose.  ALWAYS hook up the stove first and the canister last.  There is no valve inside this adapter.  If you hook up the canister first, butane will spew out in an uncontrolled fashion.

A butane adapter attached to the valve on the end of a backpacking stove's fuel hose.

OK, we're all set, let's hook up the canister.

A butane canister mated to a backpacking stove via a butane adapter.

Note how the "lug" separates.  Part of the lug stays in the notch in the collar and part of the lug rotates to the right.  The part of the lug that stays in the canister needs to stay pointing straight up.

OK, we're all hooked up.  Let's fire it up.

A backpacking stove running off of a cheap 100% butane canister

Well, heck, looks fine to me.  So what's the problem?

I'll tell you what the problem is.  Remember in the photo above how I said that the lug needs to point at the sky?  What prevents the canister from rolling over?  NOTHING.  That's right.  There is absolutely nothing that prevents that canister from rolling or turning in some fashion.  And what happens if the canister rolls?

The stove flares up uncontrollably if the canister rolls over.

WHOOMPH!  If the canister rotates or rolls for any reason, almost instantly, the nice well behaved flames we saw in the previous photo can turn into the big yellow flames seen immediately above.  Note that the above photo was taken after the flames had settled down a bit.  I knew it would flare, and I was expecting it (I turned the canister deliberately).  Still, I was surprised at just how BIG the flare was.  The flare extended out at least a foot (~30cm), maybe more on the downwind side.  Uh, hope you weren't leaning over the stove to check the stew when the canister rolled.

Why does it flare?  There's a fixed position plastic tube inside the canister.  The plastic tube points up, up toward that notch you saw in the collar of the canister.  The plastic tube is designed to suck vapor -- which it does quite well so long as the canister is oriented with the notch up.  But recall that the majority of the fuel in a canister is in liquid form.  If the canister rolls a bit, then suddenly the tube is plunged below the surface of the liquid, and liquid fuel is squirted into the burner.  Whoomph!  A flare erupts.

A butane canister valve assembly.  The notch should always face UP.

I believe that the adapter shown is fundamentally unsafe if the canister is laid on its side -- which is the most desirable way to use a tall canister.  A harsh judgement, I realize, but there just is nothing to prevent that canister from rotating and flaring.

What's that?  If your stove has a pre-heat loop, wouldn't it be OK?  Well, yes, but you'd better make sure the canister doesn't roll until the stove is warmed up.  Yes, you could use this type of canister in side laying mode on a stove with a pre heat mechanism -- if you were careful.  So be careful.

I believe this type of adapter is safe if the canister is standing up.  I strongly recommend that you use something like a Brunton Can Stand like the one shown in the photo below to stabilize the canister.  If the canister were to fall over, a dangerous, uncontrolled flare would result.

A butane canister, upright, stabilized by a Brunton Can Stand

That's my warning.  This adapter is generally not recommended.

Thank you for joining me on another Adventure in Stoving.

HJ

SUMMARY
1.  The adapter is well made, but it's too easy for the canister to roll accidentally which could cause a serious flare.  Therefore, this adapter is generally not recommended.
2.  Never use this adapter with a side laying canister on a stove without a preheat mechanism (generator).
3.  If you are cautious, you could use this adapter on a stove with a preheat mechanism (generator), but be aware that it's very easy for this type of canister to go into liquid feed mode accidentally which could trigger a flare if your stove hasn't warmed up yet.
4.  This adapter is safe if the canister is used in the fully upright position, so long as the canister doesn't fall over.  I strongly recommend that you use some means to prevent the canister from tipping over.