Dolphins may not have harnessed fire but we have and here is my example of the domestication of fire. Like most people I enjoy a good fire pit on a chilly night. What I don't like is a face full of smoke, flying embers, jackets that smell like smoke, and most of all, that horrible feeling in the pit of your stomach when you can't get the fire started and you know you will be shunned by your tribe and not allowed to mate.
To avoid all these things I decided to make a fire pit that used gas for fuel. There are many examples of these out there that people have made, some permanant and others portable. What I have noticed over the years is some of them just look nice but produce no heat while others actually work to keep you warm. I wanted one that looked nice and kept me warm. Too much to ask? I think not.
After seeing two examples of gas fire pits at burning man last year I figured I knew enough to build the pit I wanted so it was time to get started.
NOTE: Fire is dangerous and so is propane. Be careful and follow safety instructions or your life will suck big time. These are meant to give you ideas on building your own and do not contain all of the information you need.
Step 1: A proper container and hardware
One of the fire pits I saw was made by Jon Sarriugarte, he also made an instructable for it here: http://www.instructables.com/id/Sand-Fire-Garden/ His kit had almost everything I needed to complete my build. The kit came with the ring, bulkhead fitting, tape, hose, regulator, lighter, and instructions. My cauldron would have fit the 18 inch ring but I decided on the 12 inch to save a few bucks. As you can see in the finished picture the flame output did not suffer. The only thing I added was a flexible hose from Home Depot for about $13 and some high temp RTV for $8.
Step 2: So lets get started!
My cauldron is really heavy and so I wanted to avoid having to fill the entire thing up with sand. I needed the top of the sand to be about 1-2 inches from the lip of the cauldron and the burner needed to be buried under about 4 inches of sand. To do this I decided to mount the burner to a metal drum lid and insert it into the cauldron.
My first step was to cut a metal lid from a 55 gallon drum so that it would fit inside the cauldron. I wanted it tight and about 5 inches down from the lip. The metal drum lid was thick enough to support the weight of the sand and was only slightly larger than I needed. It was also free. I started by removing all the grease and nasty bits from the lid with high pressure water. Then I used a kneumatic hack saw to cut a few inches off all the way around. This was by far the longest step in the process and would have gone quicker with different tools but I was using what was on hand.
After cutting the lid to size I used a drill to make a hole in the center. This is where the fitting will pass through that will hold the fire ring.
Step 3: Plumbing the Cauldron
In all the instructions it is recommended to use rigid pipe for the plumbing inside the receptical but I just could not do that. The cauldron's sides were curved and the bottom too close to the ground. So the hole I made would be on an angle and so a flex hose was the simplest way to accomodate this.
Step 4: Burner assembly
Next I carefully lowered the assembly into the cauldron to avoid stress on the flex tube and keep the burner level. I tapped it down snug with a rubber mallet.
The final step, and this is an important one, is to fill any gaps that could allow gas to get down under the burner assembly. With the weight of the sand on top of it, the gas will want to leak down, this must be avoided or you will have a cannon and not a fire pit. To seal mine up I used high temp RTV and went all around the rim of the barrel lid where it contacted the cauldron. Be patient and let it cure for 24 hours.
Step 5: Add sand, gas, and enjoy
Fill your container with sand. I used one bag of playground sand found at Home Depot.
Connect the supplied hose to the bulkhead fitting and to the propane tank. Now your ready for flame!
Don't forget to make a cover for your fire pit. This is a closed container and any water that gets in will just sit there and rust out your burner. I used another barrel lid which allows me to cover the pit right after I turn it off and not have to wait until it cools.
Be careful when lighting, follow the instructions. Jon says to hold the flame over the sand and turn on the gas. Hold the lighter there until it catches. Now you have a burning pit of sand to enjoy. Adjust the flames as desired. I can set them low for cooking smores or crank them up for maximum heat. The 12 inch burner is plenty for this size cauldron and we have been enjoying our little fires for the last few weeks.
So in conclusion, be safe. Read and follow instructions. Keep a fire extinguiser handy. I am not responsible for you or anything you do. This is informational only and not meant as step by step instructions. Oh and don't forget to use the nylon tape on all the fittings.