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Thread: Is this flow meter adequate ?

  1. #1

    Is this flow meter adequate ?

    I am looking for a gas flow meter for natural gas (30mbar residential) for a small copper melt furnace on natural gas + air.

    I found this one.
    http://www.ebay.com/itm/LZQ-7-Flowme...AAAOSwvgdW4isv

    and some others:

    http://www.ebay.com/sch/i.html?_odkw...meter&_sacat=0

    Are these suitable ?

  2. #2
    Senior Member Robert's Avatar
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    I thought these were gas specific?
    R
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  3. #3
    The first one, MAYBE... Definitely NOT on the flow meters used for welding, pressure is too low. And actually, I'm not sure I could measure my flow rate on my natural gas burner if I wanted to. Natural gas pressure here amounts to the air flow from a whisper. I cobbled together a manometer with some hose a ruler and some water. Mine was right around 7" wc. For those that don't know, thats only .25 PSI !!! OR 17mb! I fart at a higher pressure and flow rate!!!

    For my setup, it's the fan that seems to be limiting me. I run it full out and use the ball valve on the gas line to adjust the mixture, even then it's only cracked open half way. My issue is every squirrel cage motor I try that has good cfm, sucks because of back pressure I am trying to over come. I swear, if ya want to screw with NG, you have to be part engineer. No wonder most just pay the money for propane.

    btw, Why do you care what the flow rate is? It's pennies compared to propane? If you've got 30mb, thats 12" wc. You're in great shape! Build a ribbon burner and enjoy nice even heat. Then when it's cold in the shop, use it to heat your place. ;-) I do like that first one as it would be a really accurate way to set the gas rate heading towards the burner. BUT, we know that as temp/humidity changes (density altitude changes because of this), it does effect fuel required to produce a certain heat value. At least ya don't have to add actual changes in altitude to the mix. lol
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  4. #4
    The reason is just to measure gas consumption.

    I use it for melting small amounts (<300g) of copper and that works even at a very low rate (the valve almost closed) and I add a car battery (12V) powered air mattress inflator at low power as well. That melts 200g of Cu in 15 minutes.
    The gas orifice in the burner is 3mm diameter.
    So I am curious about gas consumption.

    For larger amounts (1kg or more) or cast iron I use propane (0.5-1bar ==7-15psi) pressure.

  5. #5
    Senior Member Robert's Avatar
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    These types of meters use the viscosity of the gas to measure flow. They are standardized for the type of gas you are measuring. If you use a gas for air, oxygen or some other fluid you will need so convert your scale somehow.
    I had a thought about how you could do this. What if you run the gas at your standard rate and capture it in a water tank with an inverted container of known volume. (i.e. 1000 ml flask) Then you could measure the time to fill the flask and do some simple math. Obviously, you cannot do this in use.
    Robert
    "Whether you think that you can, or that you can't, you are usually right."
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  6. #6
    For natural gas i use orifice size and pressure. You could also fire the burner for a couple of minutes and read the supply meter, most of them are rated in 1/4 cubic ft/ most natrual gas supplies are 1000 btus per cubic ft.

    I fire natural gas on my titling furnace at about 250kbtuh it uses 3 burners. I;m needing a higher firing rate so I'm currently putting together a hybrid waste oil / NG gas burner that will fire up to about 400kbtuh. About 300kbtuh is max on a residential gas service before it starts messing with the normal equipment in the house.

    Art B

  7. #7
    Art, you need a ng pool heater. My friend has one on his pool... 400,000 btu It takes his pool from 40 to 90 in about 12hrs. I asked him what it costs to run that sucker... his answer was I don't wanna know. Lol
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  8. #8
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    Pick up a utility meter, 6 or 4 cu/f will do and just read off the index, Lots available on ebay and they are calibrated by the manufacturer. I had loads (arpoung 12 different makes ganged up for a test rig for another purpose. Bellows and valves so keep it upright (Easiest gas meter cheat in the world is to tip and stop the valves, free gas! (Most meters have tilt sense now so don't bother trying)

  9. #9
    Quote Originally Posted by jagboy69 View Post
    Art, you need a ng pool heater. My friend has one on his pool... 400,000 btu It takes his pool from 40 to 90 in about 12hrs. I asked him what it costs to run that sucker... his answer was I don't wanna know. Lol
    the pool heater is a full load for a residential service if he tried to run it and his house at the same time is where he would have problems, I'm also fighting 250 ft of pipe between my furnace and the meter, the machine shop also has a 120kbtuh furnace as well as the furnace in house. When i first built my tilting furnace i was tapped in within 5 ft of the mete, i didn't have any problems until l moved it out to the space I'm in now.

    Art b

  10. #10
    I thought you were a propane guy Art? That explains how you're rolling in 100dollar bills tilting metal into "if it fits it ships" boxes on fleabay! lol

    You selling bronze yet???? Going rate is over 5bucks a pound. You can make some pretty good coin if you can convince Rasper to teach ya how to turn copper scrap into gold! You'll have a bunch of buyers right here!
    Visit me: WWW.HandcraftedLanterns.com
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