--Trying to come up with an optimal design that will be wind-proof and reliable for a flame calliope. The plan is to have 12: 1" dia pipes spaced about 1/1/2" apart. What I need is a pilot light that will encompass all 12 of them at their throat openings. On single whistles I've used propane torch nozzles but these run very hot and a bunch in such a small space might cause other problems. Instead I'm thinking of adapting something like a porous ceramic or possibly bronze wool stuffed into a horizontal pipe with a slit on one side. Comments and suggestions welcome.
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SF Bay Area
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Re: Pilot lights?
Sat, May 10, 2008 - 1:26 PMFirst, there's no such thing as a wind-proof pilot given sufficient wind :-). That aside, the hot ticket (heh) is usually a piece of copper tubing w/ small (#50, say) holes, tightly wrapped w/ stainless steel wool (Mcmaster.com 7364T81) w/ baling (or more stainless) wire wrapped on top. Put a propane pressure regulator up-stream of a small needle valve (or just use an adjustable regulator).. the blast of propane from the opening should not directly impinge upon the wool; rather it should go right past it. The other trick is to surround the opening so that regardless of wind direction there's flame near the propane stream.
Some folks have gone to electrical ignitors (coiled nichrome wire, glowing a medium red; the power source can be a light dimmer or variac);
I think the simpler open flame approach is better if you don't need to hide the flame when the effect isn't triggered...
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-= Bart -
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Re: Pilot lights?
Mon, May 12, 2008 - 12:27 PMYEs, yes, perhaps, No, yes oh god no.
In order. I really agree with the first paragraph, except for the whole needle-valve for regulation thinge. If you get "dirty propane" with a lot of oil in it, you will get iceing around the needle valve. I really suggest against using them for tank-pressure to ignitors without having a regulator about.
Nicrome ignitors are temperamental and extremely wind sensitive. If you don't have a wind guard on them, propane will generally blow them out. Also, using a small variac or light dimmer on a nicrome system is a good way to start an electrical fire. Nicrome flows a lot of current. Will piss off things like dimmer switches (which are almost always rated to 4-6 amps constant draw.)
Stainless steel wool effects, provided between 6-10 psi of propane work really well. The other good thing about them is that they die out really quickly after propane is shut off. Probably between 15 and 30 seconds, if you limit the amount accumulation (pipe) between valve and regulator.
I'm a really big fan of design solutions to design problems (as in opposed to engineering solutions), and most pilot issues are design issues. If you take wind into effect and make appropriate shielding and placement, you'll probably have much less issue with the pilots than if you design a bad ass pilot and put it in the wrong place without shielding.
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Re: Pilot lights?
Fri, May 16, 2008 - 12:15 AMThanks for the tips guys. I should also point out that I want to try using liquid propane in a seperate application. How would you arrange a pilot light taking into consideration liquid rather than gaseous fuel going up the pipe? In other words are valve and regulator on forklift-style horizontal tanks different than 'conventional' upright ones?
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