Learn about the many ways a propane torch can be useful around the homestead.
Fire may be the closest thing to a silver bullet for all those really tough jobs around the country homestead. Whether you're melting ice, freeing a hopelessly rusted bolt or waging war on noxious weeds, absolutely nothing can hold out for long against a few thousand degrees of flame.
Maybe that's why so many folks these days are as wildly enthusiastic about "propane and propane accessories" as Hank Hill, the lovable redneck propane peddler on Fox TV's King of the Hill.
The propane torch was first introduced in the 1950s. Back then it was known simply as the lowly "plumber's torch," a nozzle screwed onto a disposable fuel cylinder. Today, the propane torch is a mega-million dollar industry of its own. Torches of the early 21st century range from sleek, brushed stainless steel butane mini-torches used by chefs in fancy restaurants to tractor-drawn propane burners that cost thousands of dollars and incinerate weeds and bugs by the acre. The field-sized flamers look like a fast-moving wildfire and sound like a jet taking off. Between those extremes are mid-sized torches that serve as patio heaters and lights, often called "outdoor living products."
You can also carry propane tanks on your back or tow them along on a dolly to fry weeds. The business end of those flame-weeders can be a hand-held nozzle or a metal hood mounted on one or two wheels with up to five burners inside. They kick out up to 400,000 BTUs an hour, as much heat as many modest furnaces produce.
Using a modern propane torch has never been easier — or safer. Gone are the days of opening the valve on the fuel tank and frantically flicking a hand-held striker to ignite the escaping gas before it went ka-BOOM in your face. You can still buy those no-frills work horses, of course, but more and more of today's propane torches come with what manufacturers call "automatic igniters." Just pull the built-in trigger, and — poof — you've lit your fire, Baby. Even when turned completely upside down, the better torches will keep right on burning now, thanks to built-in pressure regulators. Some, in fact, are made specifically to be used upside down to destroy weeds in patios, pavement and gardens.
The long and growing list of uses for propane torches today includes:
"Flame weeders are great — especially the small, hand-held models," says Mike McGrath, host of You Bet Your Garden, a weekly organic gardening show on WHYY, Philadelphia's public radio station.
"They are ridiculously easy to use. You just attach a disposable 'camp stove' size propane bottle to the long metal wand, click it on, wave the fiery tip over the tops of plants you dislike and they will dehydrate and die," McGrath says. "Perennial weeds, like dandelions, may require a second treatment – or you can just linger there a while and toast the suckers."
For dandelions and other stubborn weeds with a deep tap root, there is the "Dandy-Destroyer" from Rittenhouse & Sons in Canada. Although fueled by a propane cylinder, this ingenious device has no open flame. Instead, burning propane fires an infrared heat element which develops up to 1,800 degrees Fahrenheit. No heat is radiated sideways or up toward the operator, according to the manufacturer. It comes with a metal spike that is jabbed right into the middle of the plant, and costs about $225.
If weeds have already blossomed and set seed, McGrath advises flaming the tops thoroughly to toast the seeds, then burning the base of the plants before tossing them into the compost pile. Unlike many chemical herbicides, strong vinegar, salt and other household items often used to kill weeds, McGrath says flaming does not discolor or damage most paving stones.
The smaller the weed the easier it is to kill with a flamer. Most experts say the ideal height for successful one-pass flaming is one to two inches. Broadleaf weeds are killed by flaming more easily than grasses, which develop a protective sheath when very small.
"The idea behind flame weeding is to kill weeds with an intensive wave of heat, without disturbing the soil or harming the crop root system. Since all plants are composed of tiny cells filled largely with water, a thin blast of heat directed at the stalk will boil the water within the cell. The pressure generated by this expanding water will then explode the cell itself, rupturing a cross section of the stalk. When this happens, food and water cannot move from roots to leaves and the plant withers and dies," explains Dr. Nabil Rifai of the Nova Scotia Agricultural College in Canada.
Propane is also known as "liquified petroleum gas" (LPG or LP-gas). It is a byproduct of natural gas processing and petroleum refining. In its natural state, propane is tasteless — and odorless.
So why does propane stink like rotten eggs or a skunk? It's for your safety. Nearly 7 million homes in the United States are heated entirely by propane, the National Propane Gas Association reported in 2004. So you will know when there is a dangerous gas leak, a nasty-smelling chemical is added to propane and natural gas. Ethyl mercaptan (ethanethiol) is a major component of skunk musk. It is the smelliest substance on Earth, according to the Guinness Book of World Records. "Revolting, almost nauseating stench" is how the Independent Propane Co. in Colorado describes it.
The 12,000 residents of Emmaus, Pennsylvania, won't argue with that assessment. When workers at a propane distribution facility in Emmaus spilled just a few ounces of ethyl mercaptan on the ground some years ago, the fire department there was flooded for the next 24 hours with calls about leaking gas. As the wind shifted, the calls came from all corners of the town. No wonder. The human nose can detect ethyl mercaptan in concentrations as low as one part per 50 billion parts of air.
It doesn't take much to ignite propane. Propane's "flash point" — the minimum temperature at which it will ignite — is minus 156 degrees Fahrenheit. Propane's "boiling point" — the temperature at which it turns from a liquid into a gas — is minus 44 degrees Fahrenheit. That's why the liquid can cause freeze burns similar to frostbite. Vapor escaping in the atmosphere appears white because it condenses moisture in the air.
Propane is nontoxic. "However, when abused as an inhalant it poses a mild asphyxiation risk through oxygen deprivation," warns the Material Safety Data Sheet (MSDS). "Vapor replaces oxygen available for breathing and may cause suffocation in confined spaces."
Propane burns at a temperature of 3,450 degrees Fahrenheit in air, according to BernzOmatic, a producer of propane cylinders and torches sold at most hardware and building supply centers.
Add oxygen to propane and the flame temperature soars to 4,579 degrees Fahrenheit, adds BernzOmatic. Flame temperatures for other torch fuels with added oxygen are:
All propane and other torches are safe to use — when used safely. Problems most often arise because whatever is being heated happens to be a little too close to combustible materials. Copper water pipes, for example, are often attached to or pass through wooden wall studs or floor joists. Copper is an excellent conductor of heat. Get the pipes hot enough to solder a leak-proof joint and you may also get nearby wood or other combustibles hot enough to burn, maybe not right away, but soon after you turn off your torch and turn your back.
My neighbor recently learned that the hard way. He was fixing a leak in an upstairs bathroom, soldering pipes with a propane torch inside the wall. Red-hot flakes from a rusty pipe bracket dropped down into the floor space below the bathtub. Next thing he knew, the second floor began filling with smoke. He quickly poured water into the hole, then blasted it with a dry chemical fire extinguisher. Swallowing his pride, he also called 911.
Fortunately, damage was minimal. Drywall in the ceiling below already needed to be patched. The firefighters with a pike pole just gave the homeowner a head start on pulling the damaged drywall. Besides cleaning up a soggy mess, the hardest thing the neighbor had to do was figure out how to explain it all to his wife.
George DeVault is a fire chief in southeastern Pennsylvania.
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