reply to post by OneisOne
Disclaimer: Did this over the past 4 hours with constant interruptions from my real work. Could read choppy, and could be errors in the math, but
all the information is there for someone else to fix it if I've made a mistake. My opinion is that the official story of a leaking furnace is
technically plausible, but very highly unlikely to get the conditions just perfect, unless there was some intentional help involved. I believe it to
be an arson attempt that ended up with an unintentional explosion.
So 90lbs of gas at 10% gas to air ratio, from an underground leak that might have filtered out the noxious smell indicator, and with a perfectly timed
ignition source. Sounds extremely unplausible, but lets do the math.
PV=nRT. We're looking for Volume to see if it is possible in a 2500 square foot home.
So, convert to V=nRT/P
So 0.1 atmospheres of pressure for the 10% ratio of gas to air, converted to Pascals equals. equals 10132.5 Pascals.
P = 10132.5
n = number of moles
Natural gas is a mixture of hydrocarbons, primarily Methane, but with some Ethane, Butane, Propane, and Pentane mixed in. Methane is 16.044 grams per
mole, but I'm going to use 20 grams per mole as an approximation to account for the heavier hydrocarbons.
So, 90lbs = 40823 grams = 2041 moles
n = 2041 of 2.041 kmol
R = is 8314 (for our purpose)
T = 298 K for our purpose.
boring math.... so....
V = approx 500 cubic meters or 17600 cubic feet at 25 degrees Celsius and 10% pressure.
Assuming a 2500 square foot home has approximately 8 foot ceilings, there is an available 20,000 cubic feet of air space available.
So, the 90lb estimate of gas seems credible, but I am skeptical for many reasons. The gas would not be uniformly distributed in the house, the
concentrations and pressues would not be the same from room to room and floor to floor. An ignition source in an abandoned house seems pretty
unlikely. If the thermostat was the ignition source, it would have to be an old style, not a digitial one, and it would have to have just the perfect
concentration of gas vapor in the area of the thermostat.
The energy that an explosion of Methane could create is significant.
891 kJ per mole.
90 lbs is 2041 moles, so that is 1,818,531 kJ, or 1,818 MegaJoules of energy.
Similar to almost a half ton of TNT!
So, if you can imagine a pallet of Dynamite in your next door neighbor's home, just sitting there Wile E. Coyote style, waiting for the thermostat to
spark, that would be very equivalent to a 2500 square foot home in ideal conditions with a 10% mixture of Natural Gas having leaked into it and
dispersed evenly across the entire home.
It still seems very suspicious to me that these ideal conditions would exist by accident. Very coincidental that the furnace happened to be leaking,
the home happened to be up for sale, and the family happened to be staying in a hotel just before the explosion. I'm thinking arson, and the folks
didn't realize how powerful the gas leak could become. Arson plus negligent homicide.