Natural gas line?

Discussion in 'Burners and their construction' started by Zapins, Nov 17, 2018.

  1. Zapins

    Zapins Silver

    I remember someone uses a natural gas line for casting but can't remember who.

    What special changes need to be made for natural gas casting?

    Do you just have to hook up a regulator to an existing line or does the pressure of the line need to be increased for casting?
     
  2. Mach

    Mach Copper

  3. Petee716

    Petee716 Silver Banner Member

    Jagboy and MasterYoda among others have contributed a lot of info over on the other side
     
  4. Jason

    Jason Silver Banner Member

    You rang? The problem is NG is delivered to you at home at very low pressure. So ya gotta employ brain cells to get the job done. I have no doubt I could melt bronze in my ng forge running that ribbon burner. You WILL have to supercharge it with a blower to get the temps up. I had built my oil burner furnace before playing around with the NG and that's why I still melt with oil. The next furnace I build will be fueled with cheap ng. I want it because of the convenience and not having to store oil and jet-a, not because of saving a buck. These days, my oil burner is so light and go easy, that revamping that setup is way down on the list. Next thing I gotta build is that pool.

    I will say I can see my gas lanterns mounted on my house change a little when the house gas heater flips on. I would be a little concerned mid melt if the heater and gas water heater decided to come on at the same time as melting a pot of bronze. I would be inclined to shut the heat off during a melt. The solution of course could be to adjust the house regulator at 2am, but better would be a bigger line supplying more volume. Some day when you are making the big bucks as a brain surgeon and decide to build a dedicated FOUNDRY in the backyard... just have them plumb you in a fat ass line with a commercial pressure regulator. Barry Luke in baton rouge runs total NG in his shop. He did say it was a bit of a faff getting the gas company to get stuff right. It's local code that gets us on this one, believe me, the gas company wants to sell you tons of ng.
     
  5. Peedee

    Peedee Silver

    Most gas meters are bellows type and by nature are restrictive, and then there is the regulator, all in all I think the standard domestic meters are limited to 6cu feet per minute, and industrial 10cu feet and upwards.
     
  6. Zapins

    Zapins Silver

    How many cuf are needed to melt metal with natural gas?

    The BBQ tank is around 138 cubic feet of gas and it drains in roughly 80 minutes. So that is a usage rate of 1.7 cubic feet/min of propane to melt metal. Of course I think the pressure it enters the furnace is important to get a good melt as well.
     
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

  8. Rasper

    Rasper Copper

    It's not so much the cubic feet that is important as it is the cubic feet per minute. If your home type regulator can't deliver the needed pressure, you are spitting into the wind. Get the gas company to install a high pressure regulator. Of course they will squawk. Utilities don't want to do anything. Do your doctor routine. Anything. Medical student in need of higher gas pressure for developing a new cancer cure. Give 'em the old Coney Island shuffle.

    That's one of the great life lessons I learned about getting something done. Back in 1973 I delivered a sailboat from Virginia to New York for a Jewish psychiatrist. I was anchored in Gravesend Bay in Brooklyn. The engine wouldn't run. I bought a new exhaust manifold but it lacked a hole in which to screw a water fitting. The owner of the boat drove me to a machine shop over in Coney island. I went in and found the owner. Okay, here I am, a Southerner, a Virginia boy, very polite "Can you drill a hole here and tap it with quarter inch pipe threads?"
    "I'm too busy. I don't have time for that." He turned and walked away. Polite does not work in Brooklyn.
    I went back out to the car and told the psychiatrist what the man had said. He just looked at me and said, "Richard, you got to give 'em the old Coney Island shuffle."
    At that moment my life changed forever. I went back in the machine shop and said something like, "Look God dammit. It won't take you but five minutes to do this. Here. Let's get it done."
    In a little more than five minutes it was done.

    Richard
     
  9. Jason

    Jason Silver Banner Member

    Gas companies will NOT just install a bigger regulator. I've tried! Not without a tag from a local plumber certification. The problem is all the rest of the gas crap installed in a house.... I'm pretty sure upping the pressure to standard household gas appliances would be frowned upon by someone and the insurance company.

    Now if you can tell me how to jerry rig a regulator, I'd be game. But going the correct route is not going to happen these days. If ya build a dedicated shop, they will want you to pay for a separate service and will happily give you the pressure/flow you require. Again, a plumbers signoff will be required certing the system is safe for the higher supplied pressure.
     
  10. Rasper

    Rasper Copper

    I know. The rules and regulations that have made it almost impossible to do anything in the USA but work a nine to five job have made life difficult up there. But rules were made to be broken. You can't just go down to the gas company and tell the girl at the desk you want a high pressure regulator. You have to give the old Coney island shuffle to someone who can give you what you want. A case of beer, some conversation, a little about what you are doing, usually with a blue collar guy who drives a company truck. It's not like it was back in the 1950's when they loved their jobs. Nowadays they hate the company. They're on our side.

    Richard
     
  11. PatJ

    PatJ Silver Banner Member

    I did a work project with a natural gas generator at an airport hanger/building, and the new genset did not work right.
    The genset rep said the gas pressure was too low, so we went through a lot of trouble and some money getting the utility company to change the regulator.
    The genset did exactly the same thing on the higher pressure; ie: ran erratically.
    I turned out to be right, it was not a gas pressure problem, but rather a bad NO2 sensor on the genset.

    But changing the gas pressure required some changes inside the building, which I think may have been requiring a regulator at each device that required low pressure gas, such as heaters, hot water heater, etc., and the question was raised "Where do the interior regulators vent".
    They ended up going with some sort of ventless design.

    But the bottom line is this:
    You are liable for anything you touch or do with the regulator or gas system, and if you make any mistake, or even if they find that you have tampered with the regulator, you can be in very big trouble.
    If you tamper with the regulator and something blows up, like your house and the houses around you, assuming you live, then again you are in very big trouble.
    Natural gas leaks are very unforgiving.

    I can spill diesel or waste oil on the ground all day and not have an explosion danger.
    If you rupture or melt a natural gas line/hose, you got serious problems if you don't notice it and do something about it very fast.

    Be smart is all I can say.

    .
     
    Jason likes this.
  12. Jason

    Jason Silver Banner Member

    Someone told me to burn out my tree stump in the backyard. Except I happen to know the neighborhood gas line is right under that sucker. Big KABOOM!
     
  13. Peedee

    Peedee Silver

    An old trick with the meters is to tip them 45 degrees, the sliding valves slide and stay open and the gas flows straight through the bellows. I STRONGLY urge nobody to try this!!!!!! Most modern index are fitted with tilt sensors and as mentioned above gas leaks are killers. I worked with the guys that picked up the pieces after meter tampering and they had some pretty unpleasant stories. Always go with the correct route through the supplier and if that can't happen try another fuel.

    Edit: The above will only stop the index moving and allow a little more flow and will get you up for charges of fraud and seriously not worth the effort. We even had people banging nails into the incoming electric lines to power weed farms in lofts, lighting spirit lamps under the flexible gas feed to claim insurance on a burnt down property and even using piezo lighters to kill the processor on electronic pre-pay meters.
     
    Last edited: Dec 1, 2018
  14. Rasper

    Rasper Copper

    I'm convinced. Don't mess with gas meters.

    Richard
     
    _Jason likes this.
  15. Peedee

    Peedee Silver

    I have an aversion to playing with Ng. Wiring, plumbing anything else but Ng worries me that I just don't touch it. Helps we are off the Ng grid here. I could mention a whole bunch of supply tricks but it would be irresponsible to post them.
     
  16. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I haven't done the deed yet but I believe a high performing NG foundry furnace burner can work well with standard residential supply pressure. In fact it looks like Mach is there. I don't think increasing the NG supply pressure in a residential setting is a good idea under any circumstances and isn't necessary for a home foundry furnace burner. I had some work done at my home on a patio project and while I was at it I ran a line and tap for a foundry furnace burner and had the utility company install a high flow meter and regulator. That was no problem and the utility company did the meter/regulator change free of charge. As previously mentioned they are in the business of selling energy. They did have to perform a consumption survey n my neighborhood to make sure the neighborhood infrastructure could support the additional demand....which was more than adequate. It's still only 7-8"H20 supply pressure but has high flow capacity.

    Because of the lower fuel supply pressure, maintaining the burner in tune on an NG burner may/will have more sensitivity to pressure drop through the Tuyere and furnace but I don't think any more so than oil burners with similar crucible to wall clearances and vent diameter. There are a couple common sense things that need to be observed and I had some advice from Yoda in this regard. First off, you need to make sure your forced air supply pressure to the burner can never exceed the NG supply pressure. If it can you need back flow protection as pumping air into your residential gas system would be unwise. Most fans are low enough pressure but some can develop more than 7-8"H20. The other valuable part of Yoda's advice was managing the burner geometry and design with respect to the flame propagation speed for a given fuel. That's the part of the discussion in the previous linked thread talking about baffle plates and will insure combustion is sustainable yet not able to back up the burner tube. There will be a relationship between the fuel supply orifice size, how much gas you can push, air supply, and Tuyere/baffle size. Operating with the potential for both backflow and below the flame propagation speed can have serious consequences. One needs to remember your dealing with an unlimited supply of fuel. You need to decide if your comfortable managing these subjects and insuring your reach doesn't exceed your grasp..........a concept I've found to be a good self-preservation principle. :)

    Best,
    Kelly
     
  17. Zapins

    Zapins Silver

    Hmm lots of concerns. Here I was thinking it would be as easy as slapping on a regulator to the end of this NG line.

    I guess the gas company can install it if needed?
    20181109_181658.jpg
     
  18. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Zap, if ya really want to have a go at an NG burner, there is a certain elegance in simplicity.

    Do you know how to make a U-Tube manometer? Google it. Add some food coloring to the water and use some clear plastic tubing. Use it to measure your NG pressure. It will likely be 6"-8" of H2O. If you have a squirrel cage blower, dead head the output and measure the maximum static pressure your blower can produce. Most common fans can only produce a couple inches H20 best. Some higher performance blowers can develop much higher pressures.

    Have a look at Mach's burner and his AA build link posted earlier in this thread. I have seen a number of builds that use an unregulated 1/4" copper line or up to a 1/4" orifice for residential NG supply and a 2" burner tube. You can go to the trouble of centering the feed line in the burner tube or just tee it in and allow at least 10 burner diameters of straight burner tube length beyond where you tee in the NG. Make a valve to choke the inlet of your blower so you can adjust the air flow and as simple as that you'll likely have a pretty powerful NG burner.

    That combination of supply line, residential NG pressure and orifice, and burner tube diameter produces exit velocities low enough so it doesn't extinguish but high enough for the amount of NG being supplied to enable tuning within the limits of the flame propagation speed, as long as you have enough blower output.

    Even if your blower can produce greater static pressure than your NG supply pressure when deadheaded, it's unlikely it could do so through a 2" burner tube and create back flow into your NG line........unless the exit of the burner tube gets blocked. That's the sh!t happens scenario and why I suggest a fan or blower that is incapable of producing higher than NG supply pressures.

    Best,
    Kelly
     

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