A thin hotface medium/low mass beer keg (drum size) furnace for melting Iron

Discussion in 'Furnaces and their construction' started by PatJ, Aug 24, 2017.

  1. PatJ

    PatJ Silver

    I got started fabricating the frame for the oil pump assembly tonight.
    I had some metal from an old boat trailer, so that is what I used.

    I mounted the pump support piece in the lathe and drilled/bored a hole to match the diameter of the boss on the pump.

    The curve on the angle iron supporting the motor was cut with a vertically mounted portaband (one of my favorite tools in the shop, and probably the most used for fabricating foundry equipment).

    Not sure exactly which orientation I will mount the pump.
    I show two different configurations in the photos.
    I will probably go with the first photo, since it will allow the two fuel lines to the tank to exit vertically, and I will be able to spot any leaks in the fittings.
    I will have to support the fuel lines to keep them from kinking, but that is no big deal.

    However, if I use the configuration shown in the second and third photos, then I can mount the fuel filter as shown, and the assembly will be more compact.

    But one more consideration is the pressure gauge, which will be mounted on the top of the pump when it is in the upright position, so in the upright position, the tank lines exit the bottom of the pump, and the pressurized line to the nozzle exits towards the filter side.

    The pump (Model A) can be mounted in any position, so I guess it is a matter of which position allows connection of the fittings/hoses best.

    I think I will go with the configuration shown in the last two photos, and let the pressure gauge be on the right side, the fuel tank lines would exit on the left side, and the line to the nozzle would exit the top of the pump.


    The fuel filter is not shown in an exact location, but will probably be close to the location shown, but a little higher so the inlet can enter over the top of the frame.

    In order to align the motor and pump supports before welding them in place, I will probably cut a piece of pipe the correct length, turn the ends in the lathe, and clamp it between the two supports.
    Or better yet, make a straight solid coupling that slips onto both shafts, for temporary use for alignment.

    The motor appears to be designed to cantilever off of its front flange, but that seems like it leaves a lot of unsupported weight, so I will add a rear motor cradle with a strap.

    I have some small swivel casters.
    I should probably add those.

    Note that the pump can be removed by unbolting it and sliding it forward, and the motor can be removed by unbolting it and sliding it towards the rear.


    r20181129_025148.jpg


    r20181129_030434.jpg


    r20181129_030503.jpg


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    Last edited: Nov 29, 2018
  2. Gippeto

    Gippeto Silver

    I hope it works for you Pat, you put a lot of thought and work into it.
    Good luck!

    The issue and desire for a solution did get me thinking though...ever used a vaporizing pot burner space heater? A shallow burn pot sitting on the plinth might be a practical solution to doing a pre-heat for a drip burner. Just use something in the burn pot to act as a wick and adjust the blower speed as needed.

    I might have to look into that further at some point.

    Regards,
    Al
     
  3. PatJ

    PatJ Silver

    I have seen those vaporizing pot burners, specifically the ones used outdoors, and they work really well, but the problem with furnace burners is that fuel can cook onto the burner surfaces and create a varnish-like substance that can clog things.

    I believe that I could make a good drip-style burner using a 1/4" fuel line that flairs out into smaller copper capillary tubes (like a tree canopy), with the ends of the capillary tubes spaces around the inside perimeter of the burner tube.
    The problem with using small diameter tubing or orifices with fuel is that they tend to clog due to the cooking of the fuel that can occur, or trash in the fuel.
    I avoid clogging my siphon nozzle burner by using an inline fuel filter in the fuel line.

    I tried flattening a mig tip to get a wide spray pattern, and that worked to some extent, but then started to clog up even with a fuel filter.

    The opening in the end of a siphon nozzle tip is small, but not really so small that it will clog easily, and I have never had a siphon nozzle clog when running diesel with an in-line fuel filter.

    I did remove the o-ring from my siphon nozzle to prevent it from overheating and melting if I wanted to leave the burner in the furnace after I turn off the burner, and that work is detailed here:
    http://forums.thehomefoundry.org/in...-from-a-delavan-siphon-nozzle-oil-burner.448/

    There are some strange (I consider them strange) burner designs out there, one of which uses two tuyeres, one tuyere for the burner tube, and one tuyere to divert some of the furnace hot gasses onto the side of the burner tube.
    An example is shown here at 2:45:


    The problem I have seen with impinging flame on the burner tube to preheat the fuel is that over time (often a pretty short period of time) the burner tube degrades and melts.
    The other problem is that this preheating of the fuel is totally unnecessary for melting iron.

    I have seen this with the Ursutz style burner, where the chamber is made from steel, and it eventually melts away.

    And some have tried wrapping copper tubing around the burner tube as a preheat.
    Heated fuel will get cooked and clog up the tubing.

    There are some myths associated with oil burners, and myths can be difficult to break.
    People seem to like myths and like to look for ideas for a better mouse trap (oil burner).
    And some people promote less than optimal burner designs because they write and sell books about how to build burners, and so the more people who believe your burner works well, the more books you sell, and the more money you make.
    There is nothing wrong with writing books or making money, but I would suggest the book buyers be aware that there may be a better/simpler/more effective way to configure a burner to melt iron.

    Myth #1:

    1. Fuel has to be preheated in the burner tube in order to produce temperatures hot enough to melt iron.
    My siphon nozzle burner tube operates cool to the touch throughout an iron pour, and I get very good melt times and very hot iron.

    I have seen some who preheat their oil in some fashion before sending it to the burner just because the oil may be thick, and the viscosity may be too high to use it cold, especially in cold weather, and this makes perfect sense.
    Heated thick oil is also much easier to light when starting a burner.

    Myth #2:
    1. Using an external combustion burner for a furnace is a better configuration for melting iron than other burner configurations because it delivers a very hot gas stream into the furnace.

    The Ursutz burner I have seen that operates well has a problem in that it operates too well, and if operated at its maximum, can severely limit the life of clay-graphite crucibles and the plinth that they sit on.
    By reducing the output of a Ursutz so that it does not damage the crucible or pinth, you are basically operating it in the same heat range as a drip, pumped or siphon nozzle oil burner.
    The disadvantage of a Ursutz burner is the degradation of the steel (if it is made of steel), or the eventual degradation of its refractory if it is made from refractory.
    The Ursutz burner is also bulky and heavy, and if not insulated, produces a tremendous amount of radiated heat. Insulating a metal Ursutz burner generally will hasten its degradation due to overheating.

    I think the best and simplest burners are those that deliver unheated fuel (or fuel heated just enough to overcome viscosity issues) into the furnace and let the vaporization occur inside the hot furnace.

    I further prefer at atomizing burner (either gear pumped or sprayed) because they produce rock-solid performance, and never have to be adjusted during a melt (assuming 15 psi pressure on the fuel tank).

    Ironsides has proven that the drip style burner is effective at melting iron, but the drip-style burner configurations I tried did not work well at all.
    I noticed that ironsides does use a 1/16" orifice in the end of his drip tube (I did not try that exact configuration), and without an inline fuel filter, the orifice would be prone to clog, especially with waste oil that may have impurities in it. Using an oil filter would easily eliminate the clog problem though.
    There are a number of people who use the drip-style burner successfully, so I can only say that if you can build one, and you can get it to work well (I could not), more power to you, since you can eliminate using a geared fuel pump or air compressor.

    For me, being able to light a burner on diesel easily at any temperature, make a slight adjustment to the fuel needle valve, and then walk away and not touch the burner controls again for the duration of the melt is well worth having either a geared fuel pump or air compressor.
    I also like the simplicity of not having to have a separate propane tank and feed line that is often required (but not always) to get a drip-style burner started.

    No doubt that there is a certain thrill in getting a new or different style of burner to work well and melt iron, and hats off to those who pull that off.
    I like to experiment as much as anyone with oil burners, and so I understand that aspect of the hobby. Playing with fire is fun.

    But for day-in day-out use of a burner that is light weight, maintenance-free (or very low maintenance), does not drift in its adjustment during the melt, and a burner that produces consistently hot iron melts every time, I will choose a gear-pump or siphon nozzle burner over any other type.

    Just my 2 cents.

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    Last edited: Nov 30, 2018
  4. Gippeto

    Gippeto Silver

    Sounds like you've spent your share of time playing with these things Pat...maybe someone elses share too lol. As you say, "Playing with fire is fun". I enjoyed tinkering with waste oil burners 10-12 years back, and revisit it from time to time. Heating applications (space and water) though....never foundry...yet. ;)

    Have seen a great many ideas come and go while folks chased the elusive "blue flame" from waste oil. Rather more challenging without using electricity, which is (JMO) why folks were looking at finding ways to preheat everything.

    Preheating the incoming air is something that was being played with on the Yahoo Groups back 10 or so years, but I don't recall anyone using the flame quite so directly. Not something I'm interested in playing with, but to each their own.

    Warming the oil I do think is a good idea...up to a point. Fine line between aiding vaporization and increasing the build up rate of varnishes. But lines are replaceable and maintenance is always going to be required. Some degree of preheat will reduce surface tension and thus droplet size from either drip style or nozzle type burners and I see that as being worthwhile looking at. The fellows converting gun burners were finding this necessary at the time...or at least in vogue lol. IIRC, they were heating to ~185F, but it's been a while.

    Getting my little furnace running happily on waste oil is going to be an adventure, and I'm certain it will provide some challenges along the way, but tinkering can be it's own reward eh? lol Will be picking up some pipes/fittings to add a small blower and see where that goes.

    For what it's worth, having "BTDT, got the T-shirt"...your .02 might well be worth at least .04. ;)

    Have you tested your new burner yet?

    Al
     
  5. PatJ

    PatJ Silver

    I have not tested the new gear pumped spray nozzle yet.

    I walked in the St. Jude Children's Hospital 1/2 marathon yesterday in support of a friend battling cancer, an so I am really bushed at the moment.
    I have walked a full marathon in the past, so this did not seem so far, but the body does not like surprises like this, and so I am paying the piper today.
    I am glad I did it though; well worth the pain.

    When I started playing around with burners, I think it was about 2012, I really did not expect it to take so long to get things worked out.
    Burners, when combined with furnaces, can be tricky to optimize for iron temperatures.
    Pretty much any burner type can be made to work in some form or fashion, but getting one to work well for melting iron is a bit of a trick (or it has been for me anyway).
    For me, it was a situation of coming too far to fail.
    I was too vested with money not to mention psychologically, so I had to make it work.

    Hopefully I can get started on the pumped burner again this week.

    .
     
  6. joe yard

    joe yard Silver

    Hi Pat
    I have not had much chance to answer your post as they are getting rather involved. I have greatly enjoyed reading them and cant wait to see what you work out.
    Your work with the pump is much like mine with what I call the rube gold berg machine.

    I am wondering with the nomenclature plate declaring 7 G.P.M. at 100 P.S.I. and 3 G.P.M. with No. 2 light fuel if this is a positive displacement pump as you think. It would appear to indicate that this is a slip type pump that will be effected by back pressure caused by viscosity.
    If so as long as you use the same fuel such as the jet A you should be able to get reasonable flow consistence. You will be able to very the flow it will not be linear compared to motor R.P.M. will be set by viscosity and pressure.
    s-l500A.jpg
    With the Rube Goldberg machine. I am using a true positive displacement gear pump at <120 R.P.M. I will have to put a pressure relief valve on the output as this type of pump if restricted will develop sufficient pressure to cause damage at the weakest link down stream. The fuel flow will be linear in comparison to R.P.M., until the pressure relief opens at which time there will be no gain in fuel flow when R.P.M. is increased. I call it the Rube gold berg machine because it has a 1.5 Hp. Motor driving a pump that is intended to never deliver anything approaching 6 Gph. at 100 Psi. with a more realistic flow and pressure of 3 Gph at 10 Psi. 1 Hp will deliver 60 Gph. At 1200 Psi. For now I am depending on old Goldberg more as a test platform. It started out as a dad idea that I just kept going with although it should make a very nice test platform. In the end I will probably go with a dc motor that is not over .05 Hp with a built in gear reduction and tack output or a stepper motor. I just have to find the right one at the right price on the Chinese market.
    I do plan on using a small hobby compressor that is designed for air brush sprayers. It only weighs 8.5 lb. I have tested it with my vacuum spray nozzle and get very good atomization. When pressure is applied to the fuel on a suction nozzle it can no longer be considered as such although the air is still used to atomize the fuel. I can not say with certainty until I have it up and running to test but I expect due to the very limited amount of air. I will get a very fine mist at low R.P.M. “Fuel flow” that should be easily lit. As I increase the fuel flow I expect the droplet size to increase proportionately.
    I wish you the best of luck on your project and lets hope both of ours work with minimal tweaking! We are working on the same lines. Yours is moving a lot faster than mine. I have just had so much else going on. I bought a nice shed a couple of weeks ago from the neighbor for $100. I could not turn it down but it took a while to move it from his place to mine and I still have to pour some cement pads, place and wire it. My truck went down and I had to rebuild the distributer. For the last couple of nights and for the next couple of weeks. I will be teaching my grandson about the shop while repairing machines and cleaning. Translation, he got in trouble at school over grades so I have 2 weeks of child slave labor.

    Joe
    IMG_2656.JPG
     
    Last edited: Dec 2, 2018
  7. PatJ

    PatJ Silver

    I just started looking seriously at the pumped spray nozzle a few weeks ago, and so if you know anything at all about fuel pumps, you know a lot more than I do.
    I have been digging out information, but my understanding is still limited, and so with my previous burner builds, I am just stumbling blindly through this with hopes that I can reach a good understanding of it before it is all over.

    Here is a manual I found a few minutes ago:
    http://www.suntecpumps.com/PDFs/Installation and Service Manual.pdf
    It looks like my pump is listed on page I-2 (model #A1YA-7912), with a two-pipe diagram shown on page II-4 (figure 5).

    I did buy a pressure gauge that screws into the top of the pump (where the plug is), so at least I will know what the discharge pressure is while the pump is running.
    And I bought a spin-on fuel filter, since I figured any dirt or trash going into the pump is going to clog it.

    As far as what is inside that cover, I am not sure, so I looked around on the net to try and find a section of the pump.

    I found this manual, and while it is for a Danfoss pump, I am hoping that my Suntec is similar or the same.
    See page 7 for what I think I have.
    https://inspectapedia.com/heat/Danfoss-Oil-Pump-Facts.pdf
    Note that the Danfoss pump uses a TROCHOIDAL GEARWHEEL SET, and since I have no idea what that is, then it is pure speculation on my part as to whether my pump uses this technology.

    As I understand it, a single-pipe system has to be bled initially, and a two-pipe system does not.
    So I guess I don't need to bleed my system; one less thing.

    The Danfoss manual also warns that water should not enter the pump, so I guess it will be wise to add a bit of rubbing alcohol every now and then to the tank to absorb any condensation.
    Apparently water corrodes the internals of the pump very quickly.

    On a two-pipe system, one pipe has to enter the tank higher than the other.
    I need to verify which pipe must be higher in the tank, and how much higher.
    I am not sure if the return line can terminate in top of the tank, or whether it has to be submersed in the fuel at some level above the pickup line.

    The Danfoss manual seems to indicate that if the bypass valve is completely closed, then the pump pressure will rise too high.
    I don't understand this, since I would think if the bypass valve is closed, then the pump just acts like a single-pipe system.

    Here is a section of a fuel pump from the Audel's fuel pump book.
    Whether my pump is actually built like this pump is an open question, and not one that I can answer at this point.

    Pumped-Nozzle-03a.jpg


    Hopefully I can hook it up with the bypass valve open and figure out what the pump is doing, and figure out what the flow rate is with the bypass valve open and closed.
    I know there is an adjustment screw on the side of the pump.
    From the Suntec manual, it would appear that the pump is factory set at

    .
     
  8. Hi Pat, one thing I noticed with my car engine oil pump is that the oil filter is on the high pressure side. It may be possible to collapse the filter or some other dire event if connected on the suction side of the pump. For the inlet hose, I have a fine wire mesh basket (6" long by 1" diameter) salvaged from an airless paint sprayer: Spray paint shops are a good source of fine woven wire mesh. I'm hoping anything not strained by the mesh will safely make it through the pump to be filtered.
     
  9. joe yard

    joe yard Silver

    Hi pat
    After seeing the manual you posted. It is a good bet yours is of the same design. The good news is that it is a positive displacement pump with a regulator that is quite sufficient for your needs. The question becomes what is the actual displacement of the pump? Since you are going to drive it at a lower rpm than the nomenclature plate indicates to controls flow. This will mater greatly.
    In our situation you can use the one line system without initial bleeding. It will just delay the initial fuel delivery by a few a second The very first time you use it. This is not to say that you should run the pump dry for extended lengths of time. The oil filter is a great idea and MUST be put on the suction side for this application. Mark is correct in the usual set up is on the pressure return side but it is on the end of the pressure side where the oil goes back into the engine and has to cope with the flow of oil at only the back pressure caused by the filter. This pressure is relived by a bypass if the filter is clogged. With your system it will be at pressures well exceeding that of automotive use. You are using very little oil in comparison to that in recirculating auto engine. On the filter the input should be the feed from the tank and the output should go to the pump. If this is backwards under a vacuum situation if the filter degrades it has a much greater chance of partials entering the pump. As long as the filter is reasonably clean it will work fine. Under normal circumstances the filter will last a very long time just don’t run bunker oil or water emulsified oil. If the oil is picked up a couple of inches from the bottom of the fuel storage tank water should not be a problem. The fuel storage tank should have a sump drain in the lowest part. This should be checked on a regular schedule for water and sludge build up.
    To check the displacement of the pump you should hook a line to the suction side and pull oil from a measuring cup counting the rotations to establish the ratio of revolutions to volume. This should be with nothing other than a return line going to a ketch container just to keep the mess at a minimum.
    I would run my final test before ignition test with the pump regulator as it was sent from the factory while watching the gage. If you tested the pump displacement you will have a good idea as to the rpm needed for the volume of oil you want. At some point in rpm the pressure will level off and no further volume will be available. If you have the needed volume at this point. You are good. If not just adjust the regulator tighter until the volume needed plus a few % is reached. Be careful in that the manual stated the pump can reach as high as 750 psi. You will have to determine how much pressure your system can handle. I plan on using steel and hydraulic lines. Even with this set up if I could not reach the desired flow at or below say 250 Lb I would go to a bigger nozzle. In my case I wont have this as a concern as I will be using the little air brush compressor to atomize the oil I cant imagine hitting 20 psi. The steel and hydraulic line is more for durability and safety than pressure.
    At low pressure atomization will be very poor. The best atomization will be at higher pressure They suggest that 100 psi on a spray nozzle is optimal. This may be the case but with a flow control system rather than a pressure control system. The volume of oil being pumped through the nozzle will determine pressure and viscosity.
    I hope this helps.
    Joe
     
  10. PatJ

    PatJ Silver

    Thanks for all the info guys; I appreciate the feedback.

    The only thing I can say with certainty is that I am certain I don't understand exactly how the pump works.
    I think we can make some educated guesses though.

    The black box analogy is often helpful, which is:
    When you don't know what is inside of an electronic device, then define the inputs and outputs, and note the change in outputs when the inputs are changed.
    So if you can define the relationship between the inputs and outputs, then you can create a network inside the box that matches the original function, and it does not matter what is in the original box.

    For inputs to the pump, we have:
    1. Fuel line from the tank (low pressure fuel flow).

    For outputs from the pump we have:
    1. Output to the spray nozzle (7 gph @ 100 psi).
    2. Return line to the fuel tank (low pressure fuel flow).

    Motor data:
    1725 rpm operating speed @ 60 Hz, 1/3 hp, 120 VAC

    Pump data (as configured from the factory):
    7 gph @ 100 psi @ 1725 rpm

    Pump configuration:
    2-pipe connection (one supply line from fuel tank, and one return line to the fuel tank)

    Nozzle data:
    The nozzle will be a Delavan solid cone (blue designation) spray nozzle, rated at either 2.5 gph with a 60 degree spray angle, or a 3.0 gph with a 45 degree angle (these were the two I found in stock, I think either spray angle will work).

    Known items:
    1. The pump will be operated at a constant speed of 1725 rpm.
    2. The fuel output is desired to be 3 gph @ 100 psi.
    3. The pressure regulator adjustment screw is set for 7 gph @ 100 psi from the factory, and this setting will not be changed.
    4. As mentioned in the previous posts, it would probably be best to install the in-line fuel filter between the fuel tank and the pump input.
    5. The fuel line between the pump output and the nozzle will be automotive injector fuel line with a working pressure rating of 100 psi.
    6. The supply and return fuel lines between the tank and the pump can be rated at a lower pressure, but for simplicity, I am only buying one type of fuel line, and it is rated for 100 psi working pressure.
    7. The pressure gauge that screws into the top of the pump will be rated 0-200 psi.

    Questions:
    1. How will the 7 gph fuel output to the nozzle be reduced to the desired 3 gal/hr.
    Ans: By shunting part of the 7 gph output back to the tank via the return fuel line.
    2. How will the return fuel flow be controlled?
    Ans: By a needle valve in the return fuel line, between the pump and the tank.
    3. What pressure will the nozzle operate at?
    Ans: 100 psi
    4. What speed will the motor and pump run at?
    Ans: 1725 rpm (continuous via direct flexible coupling)
    5. Can the fuel flow rate from the nozzle be adjusted?
    Ans: Yes, by adjusting the needle valve in the return fuel line.
    6. What happens if the needle valve in the return fuel line is completely closed?
    Ans: All of the fuel delivered by the pump (7 gph) will be forced through the nozzle, if the nozzle will flow that much fuel.
    If the nozzle will not flow 7 gph, then the output pressure will increase possibly to an excessive level, so it will be a good idea not to close the needle valve completely.
    7. What happens if the needle valve in the return fuel line is completely open?
    Ans: Most of the fuel will fuel will bypass the nozzle and flow back to the fuel tank. The nozzle will most likely still output a small amount of fuel.


    So I will hook up the gear-pump pressure nozzle burner in a few days, and we will see how many of the above items are accurate.

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    Tobho Mott likes this.
  11. joe yard

    joe yard Silver

    Hi pat back again.
    I had misunderstood some of the parameters that you were going to run the pump. I apologize as this can be costly and dangerous. I have been stuck on the controlling rpm thing with mine too long. I should have red your post more thoroughly and had not realized you were doing it the way you are. I do like your analysis of a black box. Have you ever thought electronics?
    You are making a few basic mistakes in hydraulics principals related to what can and can not be seen in the box. Lets take the black box apart from a theoretical stand point.
    1 There is a gear pump inside the black box.
    A gear pump is considered to be positive displacement only in theory. They all have slip “blow by the gears” This is determined by design and several external factors. All pumps with slip. They will deliver maximum flow at minimum pressure and eventually have a maximum pressure at 0 flow, maximum head pressure
    With yours it could be as high as 750 psi at 0 flow. The manual only referred to the regulator being screwed all the way in. In some cases this would effectively remove the regulator. In others if the regulator has an internal stop before the spring is bottomed it will not allow the pump to reach maximum pressure “ dead heading”. What is in the black box?
    2 There is a regulator in the black box and what it does.
    It maintains a constant pressure, Not a constant flow by returning fluid back to the output. This output can then be returned back to the fuel storage tank, 2 pipe system “best” or simply returned to the input of the pump, 1 pipe system. Think of the output from this pump like a domestic water supply. If you open a faucet and the volume is there the pressure will not drop. Your spray nozzle is the same as an open faucet and the volume is sufficient the pressure will not drop. If you shunt the fluid back. The nozzle acts as a relief and the pressure from the shunt to the nozzle drops due to the nozzle opening to the lower atmospheric pressure. You will have a constant regulated flow but at less than 100 psi.
    A closed loop hydraulic system... Yours should be.
    This is a system where the fluid is circulated in a continuous loop. The pressure is constantly maintained by a regulator and volume is determined by the pump. In this system fluid is bled off by adding a T in the line followed by a restriction, the sprayer nozzle.
    Your nozzle has a given flow capacity at a given pressure. This is what will determine the true flow rate that you get out of the nozzle. It is fixed and without modifying the nozzle can not be changed. The only way to change the flow rate is to change the pressure.
    Your nozzle will have a given flow at a given pressure and viscosity. Increase psi volume goes up decrease it goes down. If you have a needle valve in line with the nozzle it will allow a controlled flow however the delivered fuel will not be at the full pressure unless the spray nozzle has a sufficient supply of back pressure to resist the full regulated pressure.
    This means you should place the needle valve before the spray nozzle to control flow. This will cause back pressure on the system causing the regulator to open at the set pressure.
    If your regulator is set for 100 psi and you get the desired flow rate. You have reached your goal as far as the hydraulics are concerned. If you do not then the regulator pressure must be adjusted upward or the nozzle must be larger. This is the system pressure that is maintained in a closed loop.
    I hope this helps. For further reference look up closed loop hydraulic systems.

    Joe
     
  12. PatJ

    PatJ Silver

    I hear what you are saying about the spray nozzle being a restriction on the system.
    I am not sure about moving the needle valve though, I will have to think about that one.
    I think I follow everything else you are saying.
    Fluid dynamics was not my strong point in school, and part of the reason I went into electrical.

    I will ponder this information and make a decision.
    Hopefully I won't destroy the pump and have to buy another one, but with my luck, that is entirely possible.

    I am guessing that I will be able to watch the output pressure on the gauge, and if it goes above 100 psi, I will turn the motor off.
    If it drops below 100 psi, I should be able to see that too, so maybe I can diagnose things with the pressure gauge.

    Edit:
    The way I see it, the pump will be working against two resistances in parallel, which are the nozzle (nozzle flows at 3 gph), and the needle valve (valve flows at 4 gph).
    And so I am thinking it will be no different than running two nozzles in parallel, with one at 3 gph and one at 4 gph, both at 100 psi, for a total of 7 gph at 100 psi, and this would equal running one nozzle at 7 gph at 100 psi.

    .
     
    Last edited: Dec 3, 2018
  13. joe yard

    joe yard Silver

    Pat
    I do see how you are going to do it now and yes it will work as you say and no you will not hurt the pump either way. Both will work fine. As you know with being in electronics and thinking as such electrons or fluid are going to act much the same way. The delivered energy - pressure at the nozzle will be low when the valve to the nozzle is highly restrictive, closed and high when the resistance is low, open. I like it a lot.
    I am no good with the paint program although I should fix that. As they say a picture is worth a thousand words and I am a bit Thick both in understanding and expressing myself on things such as this without pictures and diagrams.
    I am looking forward to your burner and have confidence now it will work as you describe. I wish I had more time for my foundry projects but I have took on a young apprentice. I have been given A great opportunity. I will be teaching my grandson 2 weeks a month for at least 1 month and possibly 2, machine repair welding and machining related to the shop. His father has the say on what he is doing night by night so we will be going through badly under maintained and abused equipment until further notice.

    Best of luck and will be watching anxiously!

    Joe
     
  14. PatJ

    PatJ Silver

    Thanks Joe, I appreciate the encouragement.

    I can remember going with my dad on saturdays to the family lumber mill, and while dad would catch up paperwork in the office, he would put us kids out in the shop.
    In order to entertain us, he would let us weld things, and so at age 5 I remember welding my name on steel plates, and making all sorts of hodge-podge things welded together like piggy banks and such.

    And I remember his welding lesson well. He said "This is the on-off switch, this is the heat adjustment, if it is too hot turn it down, if it is too cold, turn it up, wear this helmet and gloves, as the rod melts off, feed it in". He showed us how he welded for about a minute, and that was the end of the lesson.
    So we figured out how to weld, and we welded up a storm.
    We knew how to use the cutting torch too, and I remember using that to cut the slot in the top of my piggy bank.

    It has been a very useful thing to know how to do when building foundry equipment, and also repairing things when they break.
    When I was 16, an older brother of my friend had a 1966 corvette stingray, and the frame broke in half in front of the rear wheels.
    I brought a portable welder over with some steel plate, and I welded the frame back together again.
    And so he let me drive it, which was very cool but very dangerous, since it had a 454 LS6 engine with a 4-speed, and would do 12 second quarter miles at the drag strip in stock form.
    Luckily I did not crash it. Boy did they use to make some muscle cars that you could buy right off the showroom floor.

    Those were the days, and I highly value the things I learned in my dad's shop when I was growing up.

    .
     
  15. PatJ

    PatJ Silver

    I got this message from HT1 today and we decided to post it public so everyone can get the info all at once:

    Hey Pat,

    My furnace is about at the end of it's life she is pushing 300 Heats, and has damage where the flame directly impinges on the furnace wall, I'm thinking one repair, then start making forms for a new furnace so I'm ahead of the Failure I've looked at your build and have some questions:
    1) why is you lid hole so Large , in the drawing it shows 7.5 inch Diameter which seems HUGH, now keep in mind I'm running forced air propane, not fuel oil, but still that seems monstrous
    2) how well is the lining holding up, My furnace takes terrible abuse ,
    3) how are you getting away with no drain, I have to clean mine out alot, This is a me issue perhaps as I often charge over-sized scrap, which can fall out of the crucible
    4) do you have any hard data on how much time/fuel you are saving with the Insulation
    5) how many heats has your furnace taken and what is it's condition???
    6) what made you decide to move the crucible to within one inch of the Lid using different Pliths

    Thanks in advance
    HT1

    Here are the answers:


    1. The original lid was cast flat because I was low on refractory, and I could not figure out how exactly to cast a domed lid.
    I also did not have the correct dome shapes that I needed.
    And I had this brilliant idea that I would make the lid opening extra large, and use a mini-lid to close it down further, thus I could skim slag and add additives just by removing the mini-lid, and not having to open the main lid.

    Problems with the lid-within-a-lid design:

    The furnace is pressurized quite a bit during a melt, and so the mini lid leaked so much fire down on top of the main lid that it was not a workable situation.
    Solution:
    I found some sheet metal with the correct dome shape, figured out how to cast a dome shape in Mizzou, and made a new lid with a much smaller diameter hole in it.
    I can still so most of the skimming through the smaller lid hole, so it is ok.


    2. I only got four iron melts in last year, but since I sprayed a light coat of ITC100 on the interior surfaces, on the lid interior surface, and on the plinth, they are basically unblemished.
    I initially forgot to coat the lower surface of the lid, and it was pitted slightly after 4 iron melts.
    The ITC stops any pitting and protects the refractory very well.
    I think the Mizzou will hold up well over time; that is what I have read about it.

    3. I have never used a drain, and don't plan on using one.
    I don't overcharge the crucible, and so I don't get a lot of spills on the floor of the furnace.
    The spills I do get on the floor can either be peeled off, or with the typical iron slag splatter, just left in place.
    I don't use crucibles beyond their practical life, so I don't anticipate breaking one in the furnace.
    If I ever did break a crucible full of iron in the furnace, I would just turn the furnace on its side and run the burner until the metal melted and ran out.
    It is difficult enough to keep the tuyere and lid tight, and adding a drain just adds one more thing to leak.
    Leaking combustion gasses are hard on the refractory, so I like to minimize them.

    4. During the four iron melts I did last fall, I got some very hot iron in a #10 crucible in under an hour at 2.75 gal/hr diesel.
    With my previous high-mass furnace, I wasted 30 minutes just heating up the furnace mass before the iron would actually start to melt.
    My old furnace was at least 500 lbs of refractory.
    My new furnace is about 120 lbs of refractory.
    There is a noticable difference in the speed of the melt between a high mass and low mass furnace.
    Note that if you intend to do multiple back-to-back pours often, then there is little downside to a higher mass furnace, since the second melt is much faster due to not having to heat up the furnace.

    4A. The insulation that I finally settled in on with my furnace is one 1" layer of ceramic blanket next to the 1" Mizzou hot face, and then a 2600 F insulating fire brick outside the ceramic blanket.
    Some have said that the ceramic blanket will get brittle next the hot face, but that is a risk I am willing to take, and even if the ceramic blanket fails, the fire brick will still work.
    For fuel savings with this furnace, I would estimate that 30 minutes is saved on each melt, at 2.75 gal/hr, so maybe $4.00 per melt in diesel savings.
    For me it is more about the savings in melt time, and being able to get a very hot iron melt, which I think approaches 2,800 F.
    With enough iron melts, the fuel savings do add up.

    5. The furnace has had four iron melts, and its condition with a light sprayed-on coat of ITC100 is pristine in my opinion (I will post some photos).

    6. I have heard several iron melting people say that the lower part of the furnace is much cooler than the upper part (scavenger, Clarke-porositymaster), and both those guys have hundreds of iron melts, so I figured they know what they are talking about.
    It makes sense because in front of the tuyere, inside the furnace, the combustion air is at ambient temperature, so no doubt there is a cold zone low in the furnace, and you can actually see it in some of my open-lid burner videos.
    With the elevated crucbile, I have gotten by far the hottest iron I have ever melted.
    Clarke has mentioned plinth failures, but I think that is due to flame impingement on the plinth from his Ursutz-style burner.
    I use a Mizzou plinth sprayed with ITC100, and with stainless refractory needles, and a Delavan siphon-nozzle burner, and so far I have not had problems with the plinth.
    The burner basically impinges on the back wall of the furnace only, and I watch that spot carefully, but have not had to patch it.
    The Mizzou takes a lot of abuse and seems to work very well with the corrosive slag splatters (some refractory is not slag resistant).

    I will put up some more photos of the current condition of the furnace.





     
  16. PatJ

    PatJ Silver

    Some problems I had on the last pour:

    1. I did not leave enough gap between the furnace lid lip (that protrudes down over the top edge of the hot face), and so the lid jammed.
    I use a prybar to raise the lid, and cracked my hot face around its circumference about midway down.
    I saw what was happening and released the pressure, and the crack closed up mostly.
    I will patch the crack with ITC100.
    I am going to grind off a little around the top of the hot face to give more lid clearance.

    2. Even with stainless needles, the hot face cracked in several places.
    I have noticed this on pretty much every furnace I have seen, especially those that run an oil burner at iron temperatures.
    One the initial cracks get in the furnace, then things seem to settle into place, and the cracking seems to stop.
    I did have to put a stainless steel band around the top of the hot face to stop vertical cracks starting at the top of the refractory and propogating downward.
    My heavy furnace did the same thing, and I had to add a band at the top of it too.
    I don't think the needles do much to reinforce the refractory since it gets red hot all the way through, and steel as almost no strength when red hot.
    For areas in the refractory that don't get red hot, the needles would help hold things together.

    I immediately fill all hairline cracks that open up after every melt with ITC100.
    It only takes a tiny amount to fill a hairline crack, and I have only had to do that once across four iron pours.
    If you don't fill the hairline cracks immediately after they open, then the hot gasses propagate through the cracks and start to damage whatever is behind the hot face; in addition to increasing the size of the cracks.

    The ITC100 also reflects heat back into the crucible, since it gets very bright during a melt, and it is designed to reflect heat back into the furnace.
    The main benefit of ITC100 in my opinion is that it stops the degradation of the hot face, lid and plinth, and that is why I use it.

    2. I did not cast the refractory around the tuyere integral with the hot face, and so I have had to add a stainless band to secure that piece to the hot face.
    I support the burner tube independently so that it does not place weight on the tuyere refractory extension.

    3. I did cast the hot face upsidedown, and the bottom of the furnace is cast integral with the sides.
    No sense having any more joints than necessary in the furnace, since any cold joints in the refractory tend to open up over time and require patching.
    I did not cast the bottom lip on the furnace refractory, since I don't see the need for this item, other than to firmly center the refractory in the outer shell.
    The lower lip is just a large conductor of heat that contacts the metal shell and acts like a big heat sink, so I omitted it.
    My hot face sits on top of a layer of 2600 F insulating fire bricks.

    4. I did not cast an upper lip on the hot face, since I was trying to minimize the refractory mass, and also prevent heat from being directed conducted through the lip to the outer metal shell, which acts as a large heat sink.
    So my hot face is 1" thick throughout, and how well this holds up at the top edge over time I do not know.
    I figure I can patch the top edge if necessary.

    5. I am not sure I would put a lip around the bottom of the lid again, since this directs any leaking hot combustion gasses downward vertically between the hot face and the insulating fire bricks.
    I had to trim off the insulation and soft fire bricks down a bit at the top, and lower the outer stainless shell below the bottom of the lid lip so that any leaking hot gasses can exit horizontally, and that seems to work.
    For my next lid, I most likely will omit the lip that protrudes down.

    Photos in a minute.
    I will also update the drawing to reflect how I actually put the furnace together.

    The furnace is modular, and nothing is rigidly cemented or cast into anything else, so I can remove the outer stainless shell, remove the mitred 2600 F bricks, remove the 1" layer of ceramic blanket, and remove the hot face, all as separate units.
    If any one part (generally the hot face) gets too degraded, I can replace it without having to replace any other part of the furnace.

    .
     
  17. HT1

    HT1 Gold Banner Member

    Thank you Pat, a few things,

    What size did your lid hole eventual become????

    I made My furnace out of Kast-O-lite 30 so an Insulated Refractory , using forced air Propane, I'm getting 50 minutes brass pours from a cold start, and 20 Minute follow ups. My furnace has 300 Pours on it, and I'm a messy MF there is alot of metal in my furnace from explosions, and out dribbling ... So My thoughts,

    using a thin hotface I seriously doubt I will get 300 pours from a furnace before it fails

    I'm not a huge advocate of ITC products . the $50/ pint is a sore spot . also, I did try them on my hobby melter, and I did not see the sort of results that where advertised. I definitely did not see enough improvement to offset that price of ITC. Pat if you like it you should look at the entire product line though... the patch stuff might help you. the metal coat did me no good at all trying to run steel crucibles so dont waste time there.

    I think running Super Salamander 20 or 25's i can get away with a 13 inch bore??? any argument
    http://www.morganmms.com/media/1751/salamander-super-mgam.pdf

    OK I know a trick to make a Monolithic lined furnace with different material, My thoughts are here,
    1) The bottom 1/3 of my furnace takes Most of the damage from molten metal,
    2) the upper 2 Thirds contains most of the heat.
    3) so if i make a furnace with a 3 inch wall, but the upper two thirds only 1 inch of refractory the remainder a Kaowool product, will it significantly improve my furnace heat times. keeping in mind I will be going back for a second heat almost every time even running 20 or 25's
    4) would I be better off to simply increase my sand and flasks, and hit a monolithic refractory furnace for 3 heats at a time????

    Thanks in advance
    HT1
     
  18. PatJ

    PatJ Silver

    There is no free lunch.
    When you trade off refractory mass, you improve melt time, but I agree, a 1" hot face will not last as long as a 2" hot face, and a 2" hot face will not last as long as a 3" hot face, assuming a quality refractory.

    For me, time is money, so I would rather replace the 1" hot face every so often then have slow melts, and I generally do not do back-to-back pours, so the first pour is generally the time it takes me.
    Also, if I were not doing iron (which takes a long time to melt), I would probably go with a 2" hot face.

    The lid opening ended up being 4.5" diameter, and that seems to work well.

    If I were not melting iron and looking for minimum first-melt times, I would just use a 2" thick hot face and let it degrade slowly over time, and not protect it with a coat of ITC100.
    ITC100 does work extremely well with patching cracks that hold up to oil burner temperatures, but I am sure there are other products that may work as well that may be less expensive (ITC use to be cheap when I first started buying it).

    I use the ITC100 because I can use it in a thin putty form for patching cracks, or I can thin it with water and spray a very light top coat on the hot face for protection, and it works well at either application. The sprayed on coat is extremely thin (like a thin coat of spray paint), and it should be extremely thin because a thick coat will crack off.

    My furnace interior is 12.75" diameter, and 14" tall.
    I think this will accomodate a #20 Morgan Salamander super crucible while keeping the bottom of the crucible at the centerline of the burner tube, and give probably close to 2" clear at the lid since I went with a second domed lid.

    With a #30 crucible, will will have to either use a lower plinth (by about 1" maybe), or perhaps with the domed lid I would be ok with a #30 with the bottom at the burner centerline.
    If I had to do over, I would make the hot face shell 15" tall on the interior instead of 14" tall, but would probably maintain the 12.75" (nominal 13") interior diameter.
    A 12.75" inside diameter would give a little less than 2" clear between the widest point of a #30 and the hot face wall, which I think would be sufficient.

    I am not sure if I would use two different thickness hot face sections, since they will expand at different rates and inevitably crack at that junction (maybe not a big deal if it does crack though).
    I guess if I were you, I would lean towards a 2" thick hot face, and sort of split the difference between a fast initial melt and a long life refractory shell.

    I think a 2" thick hot face with a well tuned delavan siphon nozzle burner (or pressurized delavan oil burner with gear pump to omit the air compressor) would give good performance.
    Forced air propane works well too in a warm climate where you can keep the vapor pressure up to a decent value.
    I have seen ironsides and others melt iron with forced air propane, and BTU's are BTU's; if you have enough of them and the burner is tuned right, you can melt anything with any type fuel.

    I will redraw my furnace as-built in cad and post it here, hopefully today.

    .
     
  19. PatJ

    PatJ Silver

    Here are the dimensions I ended up with on the new furnace.

    If I had to do over again, I would omit the fire brick around the sides, and use 3 layers of 1" thick ceramic blanket instead.

    KEG-FURNACE-DIMS-01.jpg


    KEG-FURNACE-DIMS-02.jpg
     
  20. PatJ

    PatJ Silver

    And in black in white.
    Total cast refractory weight is about 140 lbs if I recall correctly.

    My plinth for the #10 is probably not quite as tall as shown in the drawing.
    Having the top of the crucible up near the lid also makes skimming a lot easier.

    KEG-FURNACE-DIMS-03.jpg KEG-FURNACE-DIMS-04.jpg
     

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