By Bob Fiorello, San Francisco Recreation and Parks (Originally posted 5/24/2010)

Previously, I gave you an overview of the topic of flame-weeding. I also mentioned that it’s not appropriate for all situations or all individuals. But, if you’ve warmed up to the idea of cooking weeds in your park, there’s still more to consider. In this installment we’ll cover equipment choices, regulatory matters and training needs.

There’s an assortment of types of flaming equipment out there, ranging from sophisticated, expensive tractor mounted devices to very basic hand held farm torches. Fuel sources vary from kerosene, paraffin, natural gas, and propane (LPG). Of these, hand held kits that utilize propane vapor withdrawal are probably the most popular for park maintenance for a variety of reasons.

Liquefied Petroleum Gas (LPG) is considered a relatively clean fuel. A lot of us are switching to LPG (propane) or CNG (Compressed Natural Gas) fuels to run our mowers, trucks, and other equipment. Many communities prefer these fuels over diesel or gas to run their fleet vehicles and municipal transit in order to reduce pollution and meet carbon emission goals. The stuff’s around and having access to large propane storage tanks is often not a problem. However, remember that LPG and CNG are not interchangeable and most equipment designed for flame-weeding uses LPG, which is easier and safer to store and transport in smaller service containers.

Typically a steel torch is connected with a suitable UL listed hose to a 20 lb. LPG cylinder or DOT bottle as it’s often called. This is the type of container most often used for gas barbeques and they’re often housed in cages like those found outside your local supermarket or home improvement store. As with a gas barbeque grill, propane vapor is drawn off the pressurized liquid within the tank to create a steady fuel source for burning. Other systems using liquid propane withdrawal require a different type of valve on the cylinder. Liquid withdrawal allows for greater fuel consumption, more heat, and can provide fuel for flame throwers like in the movies.

As the name suggests, 20 lb. cylinders are pretty heavy and require a dolly to move around easily. They can also be mounted on your back with a backpack kit – sounds like a scary proposition, but it’s actually the best way to get around. Backpack mounts also eliminate the problem of continually running over (or worse yet, torching) the hose lying on the ground when operating a dolly rig.
The torches typically range in capacity from 100K and 500K btus. You may already have one. However, it’s a good idea to purchase a torch specifically labeled (if not truly designed) for weed control purposes. There are a variety of brands to choose from. At the end of the blog you’ll find links to further direct you.

Whichever tool you choose to fire up, chances are you’ll have to run it by your local fire marshal or other fire safety official before doing so. Requirements can range from a simple written agreement to a full scale certification process depending on your location. Having a well developed, comprehensive plan can make all the difference in how warm a reception you’ll receive.

The fire marshal will want to see the proposed device, its specifications, and the manufacturers’ instructions for its proper use. And he or she will be very interested in where the propane service cylinders are filled and how they are stored. Having a certified propane storage facility already on record is a big plus, but don’t forget about in-service/job site storage and transport needs as well. Additionally, the fire marshal will be look for the inclusion of an appropriate fire extinguisher with the rig, and may require access to a charged hose within the burn zone. He or she may also require a written training program, covering topics such as propane safe handling, flaming methodology, fire prevention and emergency procedures.

The fire safety official will likely also determine parameters for when and where flaming can occur. A safety checklist highlighting this information along with manufacturer’s instructions should remain with the equipment at all times. It may be wise to propose a pilot project, starting out slowly with one or two flamer setups to better monitor the use and whereabouts of the equipment.

Whether legally required or not, a flame-weeding training program is a good idea. Again, this should include propane safe handling, personal protective equipment needs, and operating and emergency procedures. Every staff member planning to use the equipment should be provided with hands-on training in the field, which can be followed up with an annual abbreviated refresher.

I realize that all this bureaucratic, regulatory red tape can seem like a real flaming deterrent- especially in urban areas such as here in San Francisco. Perhaps you’re feeling like you’ve stepped into a burning ring of fire right about now. But many rural and agricultural communities are well accustomed to using fire for vegetation management and gaining approval in these areas should be relatively easy.

In any case, remember that burning question I raised in my last post “Is flame-weeding worth all the trouble?” In my next and final installment on this topic, I’ll make my case for why flaming is truly worthwhile when we get down to cooking up some (virtual) weeds. I can feel the heat already. Bring some marshmallows and I’ll see you there.