Using a Propane Torch Around the Homestead

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A flame weeder directs a blast of heat at the stem of a weed, disrupting the flow of food and water from the leaves to the roots.
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If you need a little more flame power, check out a four- or five-torch walk-behind model to save on weeding time.
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No need for chemical de-icers when you take your trusty torch to the steps.
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Remove unwanted vegetation in sidewalks, gravel, driveways and other areas quickly and easily with a weed torch.

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:

  • Disinfecting poultry cages. “There are no residues. We don’t have to worry about contaminating our food supply,” says Susan Watkins, extension poultry specialist at the University of Arkansas.
  • Burning grass out from under wire fences, instead of tearing up the plastic cutting string or weed whacker blades on the fence wire.
  • Heating tar, asphalt and roofing materials.
  • Drying sand, soil and other construction materials.
  • Removing paint, oil, grease, plastic and other materials from metal and other nonflammable materials.
  • Burning heavy vegetation and other debris in ditches, culverts and pond edges, brush, stumps, starting burn barrels, brush piles, campfires and backfires.

Fire Your Weeds

“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.”

A Propane Torch Known as the Dandy-Destroyer

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.

A Propane Primer

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:

  • Butane — 4,925 degrees Fahrenheit.
  • MAPP (multi-application, propylene) — 5,301 degrees Fahrenheit.
  • Acetylene (also called oxyacetylene) — 5,589 degrees Fahrenheit.

Safety First – Expert Advice

  • Light the torch as soon as the fuel valve is opened.
  • Store propane cylinders (and all other fuel containers) outside your home. A detached storage shed or other building with adequate ventilation is recommended. Containers should never be allowed to reach more than 125 degrees Fahrenheit. Store upright.
  • Supposedly “empty” propane cylinders still hold some gas fumes, which are more dangerous than liquified fuel. Always treat fuel containers as if they were full, the same as all guns should be handled as if they are loaded. Never throw empty containers in a fire. Propane torch cylinders are recyclable, but not refillable. Check with your trash hauler for recommended disposal methods, as local ordinances vary widely.
  • Avoid burning poison ivy, poison oak or other poisonous plants. The smoke will irritate not only your skin, but your eyes and lungs.
  • If you smell gas indoors, leave the building without causing a spark. Even turning off a light or using the telephone to call the fire department could cause enough of a spark to set off an explosion. Call the fire department from a neighbor’s phone or use a cell phone once outside.
  • To thaw frozen pipes, the American Red Cross warns: “Do not use a blowtorch, kerosene or propane heater, charcoal stove, or other open flame device. A blowtorch can make water in a frozen pipe boil and cause the pipe to explode. All open flames in homes present a serious fire danger, as well as a severe risk of exposure to lethal carbon monoxide. Apply heat to the section of pipe using an electric heating pad wrapped around the pipe, an electric hair dryer, a portable space heater or wrapping pipes with towels soaked in hot water.”

For Better Use

  • Torches light easier when the tank is opened just a crack and gas flow is low, advises Ken Glardon, a BernzOmatic customer service agent. Adjust flame after lighting.
  • Instead of using a flint-and-steel striker to light your torch, try a disposable, gas-fueled charcoal lighter with a built-in trigger mechanism. It will keep you fingers well away from the flame. Never try to light a torch with ordinary matches.
  • Use a torch with a pressure regulator. Without a regulator, when the torch is turned upside down, liquid propane works its way through the torch and puts the flame out
  • Size of torch flame varies with pressure in the tank. Pressure is a function of temperature: The colder the temperature, the lower the pressure.
  • Your torch has two flames, an outer flame and an inner. Use the brighter inner flame. When soldering, hold the end of the inner flame about half an inch away from the piece you’re working on, adds BernzOmatic’s Glardon.

Propane Torch Safety Is No Accident

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.

Published on Jan 1, 2007

Grit Magazine

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