LP vs Natural Gas

Greetings, Just my 2 BTU's on this discussion. LP = More energy, danger, cost. NG = cleaner, safer, cheaper, fewer BTU's. NG is a much safer/better choice. There are significant differences between LP and NG. LP has more energy (aka more hydrogen) than NG. It's dispensed at a higher pressure. So a given burner on LP vs same burner on NG (same jet or orifice). LP = more heat (say 2X). Same burner, different orifice, LP=more heat (Say 1.4X). LP is heavier than NG, and air. LP will not mix. It will fow to the low point and pool there. NG is comparable to air, mixes with it, will dissipate. Cheers, Jim Date: Sat, 31 Jan 1998 01:08:33 -0800 From: Jeremy Bergsman <jeremybb(a)stanford.edu> Subject: Propane to natural gas conversion I asked a few digests back about whether to believe the numbers I had read in the digest about jet orifice size for these two gasses. Here are the responses I've received, with their predicted answers: ************************* If it was me, I'd buy a second jet and drill it until I got what looked to be an oversized hole. Then drill the first one just one size smaller. [I like this suggestion the best, even though it costs money--JB] ************************* I would go by the ratio of sizes not the absolute - remember that the jet and burner go together and different burners will use different jet sizes. Only open up the jet to the same ratio. i.e.: .0625 what you started with (.04?) - ---------- = ----------------------------------------- .11 what you should end up with [Should this be the ratio of their areas? In either case it's .062", assuming .035 starting diameter--JB] ************************* To run a Methane (NG) burner with a #60 (.040) jet on Propane (LP) it would require a #72 (.025) jet. The approximate ratio is the Natural Gas jet is 1.6 times bigger than the Propane (LP jet*1.6 = NG jet or LP jet/1.6 = NG jet) [This works out to .056"--JB] ************************* [From the guy's gas company, edited-JB] Our NG is regulated to 7" of water (~.25 PSI?). To get 100kbtu, use a #22 bit. But anything over 40 kbtu should have a separate regulator. Use a 3.5" regulator and a #15 bit to drill the orifice block. [According to the Grainger catalog, #22=.157", #15=.180" But I thought NG was .5 PSI, so maybe this guy's is low and so I should be using a smaller hole?--JB] Anyway, if you end up overdrilling the orifice, couldn't you just limit the gas via a valve between the house and the burner? ************************* So, I've already gone to .078 and the flame keeps getting bigger. The suggestions I've received are .056, .062, .11 (archives), and .157. Sounds like the first approach wins, unless I hear something definitive soon. Thanks to: Richard Seyler, RooJahMon, Owen A. King, and Ray Kruse - -- Jeremy Bergsman jeremybb(a)leland.stanford.edu http://www-leland.stanford.edu/~jeremybb ------------------------------ End of HOMEBREW Digest #2625, 02/01/98 ************************************* ------- Shane, I've been using one for a couple of years, and really like it. I got the idea from John Isenhour. BTU rating is something like 35,000 BTU's. They do eat a lot of O2, but are much cleaner and much safer than propane IMNSHO. I dual heat my keg-tles. I have an electric water heater element installed, and I run it at 110 V or about 1100 watts. Works for me. I'll suggest something other than a ball valve for metering. It works ok, but is rather course. Keep in mind that NG pressure is about 6 inches of water of roughly .25 psi, so you can't have too much of a restriction in the line. (That is, a needle valve may be too restrictive.) Modern NG WH burners are designed to heat the inside of a cylinder, not the bottom of a kettle. I've acquired, but not tried, a couple of "antique" WH burners that have more jets and have the jets pointing straight up, (instead of out at/towards the inside of a cylinder.) Code requires that a burner of this size be vented. Your hood will probably work. The box fan in my kitchen window seems to work fine. Like most any other burner, you'll get maximum efficiency (only) at the max or rated o/p (probably 35 kBTU's.) You may need to adjust the air mix. I've got mine full open (proabably to account for the fact that it's not vented and so doesn't have a chimney *drawing* on it.) Post this to the digest if you like, but I WILL NOT ENGAGE IN ANY DEBATES ABOUT THE MERITS/SAFETY of different burners. My system is designed for occasional, SUPERVISED operation by an engineer. If you're not comfortable with any aspect of your burner set up, then you probably shouldn't be using it.... More burner thoughts. CO: If it smells "dirty" it probably is. Had access to a CO detector. Took just 30 minutes to get the CO level up over 200 ppm (lethal) using a Superb 35k BTU burner and NG in a large house! Box fan in the window over the kettle helped. Also required "outside air feed" from across the room. (January in MN, T=0^F). BUT the most effective *fix* was to adjust the burner! Gave it "Full Air" (I suggest removing the air adjuster on the Superb.) and back off on the NG just a bit. Get rid of the orange flame tips and the odor, and the CO level will drop to less than 20 ppm.... Propane vs NG. Propane has more energy, and is at a higher pressure. Therefore, the NG opening or orifice needs to be about twice the diameter of the propane orifice. If you have one, want the other, plug the old one w/ a screw, and drill a new one of the appropo size (twice or half the diameter). Propane is more dangerous. It's heavier than air, will sink, will not mix as readily, and therefore is explosive over a much wider range of "fuel-air" ratios. NG is lighter than air, has less energy, burns cleaner and is cheaper. If you can swing it, NG is the way to go.... Good brewing, Jim ------------------------------ http://www.menet.umn.edu/~jellings/ * * Dr. James Lee (Jim) Ellingson Ph.D. jellings(a)me.umn.edu * * University of Minnesota, 125 Mech. Engr. tel 651/645-0753 * * 1569 Laurel Ave., St. Paul, MN 55104 fax * ----- End of forwarded message from Jim Ellingson -----