Well, after tons of research I've finally purchased my first batch of components from Poofer Supply! An accumulator, various regulators, pressure gauges, hoses, and a slew of irritatingly specific brass fittings for connecting everything together.
Research involved reading about existing projects which have used flame effects at a large scale, like the Flaming Lotus Girls' Serpent Mother, as well as thoroughly inspecting diagrams of poofers available online. Additionally I emailed Seth Hardy of Propane and Electronics to ask some specific questions about my design. Seth was incredibly helpful, helping me continue to form my understanding of all the design considerations involved in a system like this.
My original design for the poofer system was definitely very ambitious and non-specific enough:
I've reduced the scope of the project for now to a single poofer + lotus prototype so I can decide on the lotus' dimensions and the ambient effect of the poofer.
In researching these are some of the concepts I've found (hopefully correct):
- LPG won't ignite unless oxygen is present. This can present a problem when you have a new accumulator at atmospheric pressure and you want to introduce propane into it for the first time. In order to prevent your ignition source from backflowing into your accumulator and causing it to explode, you must flush out the oxygen with an inert gass, or propane.
- There are two things which control the kind of flame effects you produce. The pressure of the LPG being expelled from the system, and the quantity of vapor LPG which is ignitable in one moment. If you want bigger poofs, you need both higher pressure, and larger conduit. If you want longer-duration, use high pressure and smaller conduit. If you are running at a low pressure, your large conduit will carry the LPG quickly, but it will ignite in a quick burst because it is all availible for ignition more immediately.
- If you are regulating your LPG's pressure to < 150 PSI then you can use schedule 40 piping. If you plan to use unregulated propane or you expect to exceed 150 PSI, you must use schedule 80 tubing rated for 250 PSI or above.
- Every accumulator/fuel source must have an emergency 1/4 turn shut off valve to pass inspection at Burning Man. A length of hose connecting a fuel source and an accumulator should also have a 1/4 turn valve, as a considerable amount of fuel can be trapped in the hose.
- The proper thread seal tape for your components is the yellow teflon kind.
- There are different fittings one can use to connect to a propane tank, I'm using POL (named after the company which developed them Prest-O-Lite).
- You can't weld onto ANY fittings or pressure vessels which operate at pressure. A certified ASME welder must make the alteration.
- All propane tanks & accumulators are DOT certified (because they are transported on roads), so any certifiable flame effects must have an up to date DOT registration stamp on the cylinder. AKA no you can't use that 10 year old propane tank you found in your shed as an accumulator.