Butane vs propane torches: what changes at the bench

The two fuels sit close enough together that a specification sheet rarely settles the argument. What separates them shows up in four places: cold mornings, heavy sections of metal, wind, and how long you intend to keep the flame lit. Everything else is detail. Both are liquefied petroleum gases, both store as a liquid and burn as a vapour, and both will handle most bench work - the difference lives in the margins.

If your work is a couple of joints on 15 mm or 22 mm copper in a warm kitchen, the difference is largely academic - either fuel will do the job, and the tool already in your bag is the right one. If it is a January morning on a roof, or a long run of 28 mm, the fuel decides the whole set-up.

One more variable gets left out of most comparisons: the nozzle. The fuel sets the ceiling on how much heat is available, while the nozzle decides how that heat lands on the work. A broad, soft propane flame can put less useful heat into a small fitting than a tight butane flame aimed at the socket.

This is the one physical difference worth memorising. Butane loses vapour pressure as the can gets cold: a chilled cartridge simply delivers less gas, so the flame shrinks even though there is plenty of fuel still inside. Propane holds its pressure far better as the temperature drops, which is why propane kit is the winter default on site. The effect is gradual rather than a switch, so you usually notice it as a job that suddenly takes longer than the same job did in September.

You can work around a cold cartridge. Keep it at body temperature before you start, shield it from draught, and do not let the can ice up during a long run - frosting on the outside of the can is the cartridge telling you it is struggling. Swapping between two part-used cans gives each one time to recover.

But the workaround has a limit, and in genuine cold the propane set-up wins outright. The pattern to recognise is a flame that starts well and fades over a minute or two of continuous use: that is the cartridge cooling under draw, not the gas running out.

Ranked by direction rather than by numbers: a butane flame in ordinary air sits at the bottom of the range. Propane in air burns hotter than butane in air. Feed either gas with oxygen instead of air - oxy-butane or oxy-propane - and the flame temperature climbs substantially again. Where you need an exact figure, take it from the appliance maker rather than from a fuel comparison - burners differ as much as gases do.

Our EN417 torch head is quoted at up to 1300°C. That is a burner figure for that head with the gas it was designed for - not a property of butane, and not a number taken from the cartridge standard. Any other appliance figure you need to rely on should come from whoever made that appliance.

What matters at the bench is not the peak figure but the rate: how fast heat goes into the joint against how fast the surrounding metal conducts it away. A heavy copper fitting next to a valve body is a heat sink. If the flame cannot out-run the sink, no peak temperature will save the joint. That is the practical reason people move up a fuel: not peak temperature, but delivery rate.

A cartridge head is the fastest tool to get lit: no cylinder, no regulator, no hoses, one hand free, electronic piezo ignition, and a head that weighs around 95 g. It lives in the tool bag permanently rather than in the back of the van, which is why it gets used.

For most plumbing work, heat-shrink, paint stripping, thawing and light brazing, that convenience beats raw output. You open the bag, screw the head on, press the ignition, and you are working before a cylinder set would have been unfolded from the vehicle. Heat-shrink and paint work benefit as well: a controllable flame is kinder to the surrounding material than a fierce one.

A propane set-up carries a cylinder, a regulator and a hose, and takes longer to rig and to pack away. In exchange you get endurance and cold-weather behaviour that a small cartridge cannot match, plus a flame you can hold on a heavy joint for as long as the metal needs.

Outdoors, wind is usually the enemy rather than temperature. Our cartridge head uses a built-in mixing fan, which keeps the flame stable when a breeze would otherwise tear it off the joint - one of the few places where a small design detail genuinely changes what a tool can do.

Wind still costs you heat, though. Shield the work with a board or your own body, work from the leeward side where you can, and accept that an exposed joint simply takes longer than the same joint indoors. Planning for that is easier than fighting it.

Indoors, ventilation matters more than fuel choice. Any flame in an enclosed space consumes oxygen and produces combustion products, so work with a window open, keep combustibles clear, and never leave a lit torch standing unattended. The pre-use safety checks cover the rest, and they apply to a small cartridge flame just as much as to a cylinder set - the size of the flame does not make an unventilated room safe.

Reach for a cartridge head for: capillary soldering on domestic copper, heat-shrink, thawing, small brazing work, aluminium repair with low-temperature rod, and anything done up a ladder or under a sink where you have one hand free and no floor space.

Move to propane or oxy-fuel for: large copper sections and repeated runs, heavy fittings that soak heat away faster than you can put it in, steel work, and any brazing job where the joint mass outruns an air flame. At that point you also change nozzle series - see brazing nozzle sizes.

There is a middle case worth naming: the occasional job that is too big for a cartridge but does not justify a full oxy-fuel kit. A hand-held propane burner on a small cylinder covers it, and is worth owning if you meet that case more than a few times a year. It travels better than a cylinder set and needs no regulator to be checked before use.

Per hour of flame, a small cartridge costs more than bulk propane. That is the honest trade, and it is worth stating plainly rather than pretending the convenience comes free.

Set against it: no cylinder rental, no regulator, no hose, nothing heavy to carry up a flight of stairs, and nothing to maintain beyond a seal and a clean nozzle. For a tradesperson doing a few joints a day, the cartridge wins on total hassle even where it loses on unit cost. There is also no regulator to have tested, no hose to perish, and nothing to leak in the back of the van.

For someone burning gas for an hour at a stretch, the maths flips the other way. Buy gas locally either way - it is cheaper and quicker than having it shipped - and if you are stocking a team rather than a bag, ask through the wholesale page.

Warm, indoor, small diameter, short runs, one hand free: cartridge butane. Cold, outdoor, heavy section, long continuous heat: propane, or oxy-fuel if the work is brazing rather than soldering. Plenty of jobs sit in the overlap, which is why most working vans end up carrying both.

If you are deciding between soldering and brazing at the same time, the fuel question follows the joint rather than the other way round - soldering vs brazing sets that out. And if the flame has gone yellow, sort that before blaming the gas: most of the time it is a dirty or damaged nozzle, not the fuel.

Whichever you pick, the cartridge connection is the part people get wrong. Our EN417 cartridge compatibility guide explains what the standard actually covers and how to check a can before buying a head to fit it.