From: Rick B. (GM) <ric...@gm...> - 2009-04-24 18:56:40
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I ordered a gas meter off ebay a couple years ago that measures flow in M^3. It has a reflective spot on the counter. Somewhere on the inet there was a photoeye circuit that could read the spot. Never got around to building the circuit, but the meter is very accurate. I think it cost ~$30. Rick On Thu, 2009-04-23 at 18:38 -0500, Rohn Shearer wrote: > Thanks for the replies. I am not looking for anything as complicated as > weighing the tank. The tank I am monitoring is 500 gal & has a percent > gauge on it which I assume operates off of pressure. I realize it > flucuates with temp, but that is all I really need, just something so I > have an idea if I need to order more without going outside when it is > -20 F or colder!! I would like to get a fairly accurate flow rate > though. I will try googling. Thanks > > sean mathews wrote: > > Just how accurate do we need to be : c ) This may not be 100% correct > > but the concept should work to get a fairly accurate reading, and its > > less scary than putting a tank of flammable liquid on some moving > > platform as I am sure that violates some safety/sanity code. > > > > To calculate the weight of propane in your tank based upon ambient > > temperature and the liquid level in a tank. > > > > Adjustments to this can be made based upon ambient temperatures by > > adjusting the specific gravity data ( formula below ). > > > > Using warm water or something to tap with locate the liquid / vapor > > line and mark with chalk ( automate with a string of 1wire > > thermisters? ). > > > > Below mark is LP liquid. LP liquid specific gravity is 0.51 ( to > > water ) Above mark is LP Vapor beginning to liquefy or settle. LP vapor > > specific gravity is 1.5219 ( to air ) > > > > If your tank were a perfect cylinder you can then determine the volume. > > > > Lets say your tank is 2 feet in diameter and 13 inches tall ( π • r² ) > > would be 452.38 cubic inches for every 1 inch of height in the tank. > > > > WEIGHT = (SG OF LIQUID) * (WATER WEIGHT PER VOLUME MEASURE) * (VOLUME) > > 133.34 oz = .51 * 0.5779259 * 452.38896 (1 inch below the line) > > 8.3125lb @60 degrees and @10 degrees it will be 11.42 lb's > > WEIGHT = (SG OF GAS) * (AIR WEIGHT PER VOLUME MEASURE) * (VOLUME) > > 68.82 oz = 1.5219 * 0.00833 * 5428.66752 12 inches above the line > > > > Total weight @ 60 degrees is 12 lb or 202 oz > > > > Facts: > > > > Water is 0.5779259259259259259 oz per cubic inch. > > Air is 0.008333333333333333333 oz per cubic inch. > > > > Formula: > > > > Specific gravity correction formula to compensate for temperature. > > correction = 1.313454 - 0.132674*T + 0.002057793*T*T - > > 0.000002627634*T*T*T > > SG_corrected = SG + correction > > > > Does this work for LP as well as water or was this based only upon > > water? Need to see the book "Handbook of Chemistry and Physics (CRC)" > > Anyone have it? > > > > > > References: > > > > http://www.npga.org/i4a/pages/index.cfm?pageid=633 > > http://www.gordonengland.co.uk/conversion/density.htm > > http://www.primetab.com/formulas.html > > http://brewery.org/library/HydromCorr0992.html > > > > > > Regards > > Sean Mathews > > > > > > On Wed, 2009-04-22 at 10:59 -0600, Randy Ridley wrote: > > > >> LP has a tendency to change volume with temperature. The only reliable > >> way to determine tank level is with a weight sensor on the tank itself. > >> When I had a 1000 gal tank, I used a truck spring with a linear > >> potentiometer. It had horrible reliability. If I were to do it again, I > >> think I would use a strain gauge on the truck spring. > >> > >> Randy > >> > >> On Wed, 2009-04-22 at 08:16 -0700, Sean Mathews wrote: > >> > >>> Hay Rohn. > >>> > >>> I am sure they make a flow meter for this. Just google "flow meter LP" > >>> > >>> http://www.sierrainstruments.com/products/pdf/boiler_trak.pdf > >>> > >>> I expect that most you will find though will cost a pretty penny. If > >>> you do find any inexpensive ones let us know. > >>> > >>> The level is trickier. I am sure it could be done with an array of > >>> thermisters to detect the temperature difference of the metal of the > >>> tank where the level of the liquid is. > >>> > >>> Re > >>> Sean M > >>> > >>> > >>> > >>>> -----Original Message----- > >>>> From: Rohn Shearer [mailto:ro...@sh...] > >>>> Sent: Wednesday, April 22, 2009 4:38 AM > >>>> To: mis...@li... > >>>> Subject: [mh] Monitoring liquid propane level & useage > >>>> > >>>> > >>>> Is there any way to monitor the tank level or usage of LP? Thanks > >>>> > >>>> > >>>> > >>> ------------------------------------------------------------------------ > >>> -- > >>> > >>>> ---- > >>>> Stay on top of everything new and different, both inside and > >>>> around Java (TM) technology - register by April 22, and save > >>>> $200 on the JavaOne (SM) conference, June 2-5, 2009, San Francisco. > >>>> 300 plus technical and hands-on sessions. 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