Working pressure nozzle system specs, pressurized fuel tank?

Discussion in 'Burners and their construction' started by Laekelu, Jan 25, 2024.

  1. Laekelu

    Laekelu Copper

    I've been searching on the site and learning a huge amount. I really appreciate how much you are all willing to share. I'm new and designing my furnace and burner. I've read and searched for about a month now and have a few unanswered questions.

    I have read several threads about pressure nozzle burner design that have lots of details, but I haven't found any that show specifications for well tested and functional burners.

    I am searching for the following information regarding melting aluminum and iron in a fairly large furnace (6"dia x 15" tall crucible at the largest, minimum 2" clearance on sides) using a mix of waste oil and diesel:

    1. Which pressure nozzles work best? ie. Delevan .55-60A, .75 - 80A, etc. Looks like 0.75 GPH siphon nozzle work well, is it the same with pressure nozzles?
    2. Has anyone found a difference in pressure nozzle spray patterns? Hollow vs. full? I am mainly interested in single nozzle setups.
    3. What pressure do they work well at? Seems like around 100psi works from what I have read, but I haven't seen confirmation of that pressure in a working furnace.
    4. Are there any problems with using an air compressor to pressurize a fuel tank rather than a fuel pump?
  2. Tops

    Tops Silver Banner Member

  3. Laekelu

    Laekelu Copper

    Hi Tops,

    I have access to stainless sched 40 and 80 pipe offcuts from work. One project I have in mind is a 12"diameter x 2.5" thick bending die, which I think will take a little over 2 gallons of aluminum, so that crucible size was based on a chunk of pipe I grabbed. I know stainless isn't ideal, but it's free...
    I thought it was a decent shape because it wouldn't make the furnace too wide. I was worried that an 8" dia crucible might limit furnace use when using smaller crucibles.
    I am considering making an extension ring on the furnace so it can be operated with a tall crucible or a shorter crucible without having excess furnace volume above the crucible.

    Is there a better approach to making a flexible design/crucible shape that I should consider?
  4. Tops

    Tops Silver Banner Member

    Hey Lars,
    I am a neophyte at liquid fuel/nozzle systems, I have only gotten as far as testing mine with water.
    Lots of variables in such a system as you noted above.

    Maybe a sch 40/80 pipe is the way to get that 2 gallons (US or imperial?) of aluminum, otherwise you are looking at an A50 for 8 liters capacity. Do you get other shop privileges along with scrap? I miss that sort of shop environment sometimes.

    Liquid fuel furnaces do better with ample side room and extra depth, to have plenty of room to burn the fuel.
    My current A10 design is almost 2x taller than the crucible to allow for a tall plinth. I am not done building it so I cannot offer much beyond conversation.

    Right away I would look at @Melterskelter and what he is doing with a fuel pump.
    I want to say that @Ironsides is using a pressure tank.
    Both are successful with cast iron.
    If I have this wrong, mia culpa, running from memory and not a recent search.
  5. Laekelu

    Laekelu Copper

    Thanks Tops,
    That makes a lot of sense. Instead of haven't seen adjustable height furnace I could make a couple different plinths to keep the crucible in the best position.
    I'll take a look at those designs. I also found Mark Presling's YouTube videos that show exactly which fuel pump and nozzle he uses.
    Tops likes this.

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