Jimmymm Posted June 11, 2018 Share Posted June 11, 2018 Long time listener, first time caller. Due to the great information here I was able to build my first coal forge several months ago, and now working on a forced air propane forge. Which brings me to my question... My forge is outside in a large sand area, and to simplify the process I would like to keep the propane tank and air source in an isolated area, and run the air and gas mixture about 35 feet to the forge. Due to the cost of 1" black pipe and fittings, I have considered running 1" PVC pipe the first 30 feet, and running black pipe the remaining 5. The gas/air mixture will remain cool until the last foot or so, which makes me think the PVC should be fine. Is this an inherently stupid idea? Are there any gotchas I need to be aware of? Thanks in advance! Jim Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 11, 2018 Share Posted June 11, 2018 Have you heard of static electricity generated by flowing gasses? Or NO! Quote Link to comment Share on other sites More sharing options...
Jimmymm Posted June 11, 2018 Author Share Posted June 11, 2018 7 minutes ago, ThomasPowers said: Have you heard of static electricity generated by flowing gasses? Or NO! Yes, but didn't consider it when crafting this idea. I've been around long enough to understand that I truly know very little about anything... hence the question. Back to the problem at hand - is there any concern with mixing the fuel/air in the black pipe and running it the entire 35 feet to the forge? I would consider rubber hose as well for the flexibility, but I doubt there would any savings. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 11, 2018 Share Posted June 11, 2018 The term Bangalore torpedo comes to mind. I do not suggest "storing" any combustible mixture of fuel and air at any time. Quote Link to comment Share on other sites More sharing options...
JHCC Posted June 12, 2018 Share Posted June 12, 2018 Welcome to IFI. If you haven’t yet, please READ THIS FIRST!!! Quote Link to comment Share on other sites More sharing options...
Jimmymm Posted June 12, 2018 Author Share Posted June 12, 2018 2 hours ago, ThomasPowers said: I do not suggest "storing" any combustible mixture of fuel and air at any time. I should have been more clear. My original plan was not to store the propane and air mixture, but to add propane to the airflow as it barreled down the pipe toward the forge. Ha, certainly not a Bangalore torpedo, but I leaned sometime new today. Thanks 1 hour ago, JHCC said: Welcome to IFI. If you haven’t yet, please READ THIS FIRST!!! I certainly have read it, quite entertaining actually. BTW I loved the person specific mentions, I sense a real history here. Thanks for the reminder to add my location. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 12, 2018 Share Posted June 12, 2018 If it's going through a pipe longer than say a foot; then you are storing a combustible mixture. STRONGLY NOT SUGGESTED. I live near a University justly famed for it's explosives research; some trickles down in our small town. Are you familiar with a fuel air bomb? Strongly suggest to strenuously avoid anything like it!!!!! Just lighting my gas forge by turning on the gas and throwing a kitchen match at the front opening spooks some of my friends up there. Quote Link to comment Share on other sites More sharing options...
JHCC Posted June 12, 2018 Share Posted June 12, 2018 Why not run separate pipes for gas and air and mix them at the forge? Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 12, 2018 Share Posted June 12, 2018 Welcome aboard Jimmy, glad to have you. If Thomas hasn't been clear enough let me rephrase his response. NO! A 35' length of pipe with a PRESSURIZED fuel air mix is a BOMB. Even if it isn't pressurized it's a bomb. Why in the world do you want to do it this way? Sure keeping the propane tank outside the shop and piping it in is a good plan, code requirement in most places. Why pipe the air in, isn't there enough in the shop? Carbon monoxide and oxygen depletion makes it suicide if you want to do any smithing in a sealed chamber. Considering minimum safe ventilation puts all the air your forge burner is going to need in the shop without need to pipe it in. I have to admit this IS a new one on me. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
swedefiddle Posted June 12, 2018 Share Posted June 12, 2018 Jimmy, DO NOT USE PVC PIPE!!! Plastic pipe work hardens with time (the pressure is never consistent, expansion & contraction happens). Only introduce your fuel when close to the forge, unless you wish to have the biggest Hand Grenade and want to kill your family!! It is best to have the fuel shut-off on the tank, within a short distance of where you are working. PLEASE Play Safe!!!! It is not just your life you are playing with! Neil Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 12, 2018 Share Posted June 12, 2018 Since propane eats acetylene hose (not T rated) and seals in regulators not rated for it. I would not want to experiment on it's effects on PVC over time. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 12, 2018 Share Posted June 12, 2018 5 hours ago, Jimmymm said: My forge is outside in a large sand area, and to simplify the process I would like to keep the propane tank and air source in an isolated area, and run the air and gas mixture about 35 feet to the forge. Due to the cost of 1" black pipe and fittings, I have considered running 1" PVC pipe the first 30 feet, and running black pipe the remaining 5. NO!!! Fuel gas and air is an EXPLOSIVE MIXTURE. Burners have mixing chambers of a few inches up to a foot long. What you are proposing to build is a 35 foot long pipe bomb, and hope it never goes BOOM! Quote Link to comment Share on other sites More sharing options...
Jimmymm Posted June 12, 2018 Author Share Posted June 12, 2018 Thanks for all the feedback. No need to fear, I quickly realized my mistake and am working on a new plan. To clarify, my forging activities are entirely outdoors, located on a 1,000 sq ft area of pure sand. I was planning a forced air burner that would introduce the propane to the airflow earlier in the line, rather than near the forge. This would have let me place the blower out of the way, and reduce the motor noise to practically zero. It would also let me more easily manage the propane bottles, connections, and storage. I'm still working out the details of a new plan, let me know what you think of the following... - Run 30' of 1" PVC for the airflow from the blower. The blower will still remain remote and quiet. - Switch to 1" black pipe for the next 2 feet, at which point I install a shutoff valve to control the air volume. Follow-up with a short nipple. - Run a propane line to the black pipe, with a propane shutoff valve 6 inches before entering the pipe. Run the final 12 inches of black pipe directly into the forge. This plan eliminates the long run of mixed fuel/air. It also provides shutoff valves close to the working area, and eliminates propane from flowing in anything but black pipe and brass. How does this sound? Do you see any gotchas with this plan? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 12, 2018 Share Posted June 12, 2018 Long run of small pipe will be hard on the blower to push enough air. My forced air burner uses over 2" blackpipe to the forge and the sound of the burner is way louder than the sound of the fan. Search the net for Peot Forge for plans and pictures of what I built at a blown forge building workshop put on by SOFA with Mr Peot overseeing us as we built them. Perhaps you could use a quiet air pusher close to the burner? Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted June 12, 2018 Share Posted June 12, 2018 A couple more things to keep in mind. Elbows/corners will slow your flow. They are good for mixing, but should be avoided or minimized before that point if possible - especially on the air side. Air by itself is no problem. Propane by itself can't burn. The issue is once they combine. Keep this in mind with all your designs and try to make sure there is no way for the two to mix anywhere other than where you want them to mix. One cardinal rule of blown burners is ALWAYS turn the fuel off first and leave the air on for a little while to ensure that you have completely purged the mixing tube and burner of flammable/explosive gases. If you have even a small leak which allows your fuel gas to enter the mixing tube after you shut down, over time that will fill with a mixture of gas and air. When done close ALL of the valves between the fuel source and the forge. You should have a shutoff valve close to the forge that you can easily and quickly reach in addition to at least one at the source. It's best if you can regulate flow/pressure at the source. This puts less strain on your lines leading to the forge, and in the event of failure doesn't dump as much flammable material into your workspace as quickly. You can use a needle valve near the forge to fine tune your fuel stream. Everything fails with enough use and time, so do not assume that the system which held up ok yesterday will work forever. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 12, 2018 Share Posted June 12, 2018 The burner flame tends to be 3-4 x as loud as the blower. You are solving a problem that doesn't exist by redesigning a centuries old design without understanding how they work. Don't worry, that's normal enough I think most of us do the same thing, experience tells us to just think about it rather than do it till we have a working handle on whatever it is.. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 12, 2018 Share Posted June 12, 2018 Well I was figuring he was using something noisy like a shop vac instead of something that would work better like the fan shown on the Peot Forge pages... (I picked up a fan to use for a forced air burner at the "black hole" at Los Alamos---it has AEC marked on it...) Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 12, 2018 Share Posted June 12, 2018 Good point, I hadn't thought of that. You can put a shop vac in a cardboard box and quiet it significantly even leaving plenty of vent area for air flow. I've been picking up mattress inflaters for a couple bucks, at garage, yard, etc. sales for years. They put out enough air flow to accelerate the fire burning my brush piles approx 10' around x 4' high and will turn a camp fire into a blast furnace, IF you use their full air blast. I use one for a portable solid fuel forge under a restricted flow. I haven't tried one to drive air for a gun burner but I believe it'd be more than enough to fire a good sized forge. They're not as loud as a gently blown charcoal fire. They come in 12 v DC and 120 v ac under $20 at Wally World. The 12 v DC work just fine on a battery charger. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted June 12, 2018 Share Posted June 12, 2018 Regular schedule #40 black pipe--or fuel hose--can be used to run the propane to your burner. The wine of an electric fan is nothing compared to the roar of a high speed propane flame. A naturally aspirated ribbon burner makes an end-urn around both problems. Quote Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted June 13, 2018 Share Posted June 13, 2018 It's human nature to complicate the simple. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 13, 2018 Share Posted June 13, 2018 1 hour ago, Irondragon Forge & Clay said: It's human nature to complicate the simple. Indeed. I'd have more to say but I'm still trying to get the image of Mike's "end-urn" out of my head. The NARB is still louder than most forge blowers of similar capacity but WAY quieter than the same inducer and a single outlet. Think oscillating room fan compared to a leaf blower for example. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Jimmymm Posted June 14, 2018 Author Share Posted June 14, 2018 On 6/11/2018 at 8:37 PM, JHCC said: Why not run separate pipes for gas and air and mix them at the forge? This is my current plan, run separate PVC line for the air and black pipe for the gas. I also have a foundry to melt metals, so I'll Tee off the run the line to both burners. 18 hours ago, Irondragon Forge & Clay said: It's human nature to complicate the simple. You can say that again. This often comes from a lack of knowledge of past success and failures, but I have a habit of proving this statement true. On 6/12/2018 at 9:26 AM, Frosty said: The burner flame tends to be 3-4 x as loud as the blower I was surprised at how loud the burner was in my testing. I didn't expect it to be so much louder than the blower. I guess I really have been trying to solve a problem that doesn't exist. I'm glad I'm solving these problems before the build, rather than finding out about them after. Thanks again for all the great feedback, Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 14, 2018 Share Posted June 14, 2018 This is a great place to share past mistakes and not be embarrassed about them. I've made a million of them. A burner flame is a controlled explosion, the faster the louder. This is the reason an oxy propane torch is so much louder than oxy acetylene. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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