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3000# Lp Gas Explosive power potential

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Forum topic by TopamaxSurvivor posted 12-05-2016 05:39 AM 538 views 0 times favorited 9 replies Add to Favorites Watch
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TopamaxSurvivor

18086 posts in 3509 days


12-05-2016 05:39 AM

Topic tags/keywords: 3000 pound 750 gallon lp gas explosive power

Hello LJs, I am hoping to tap into the tremendous knowledge base we have here on LJ.

Does anyone know how to calculate the explosive force of 3000 pounds (750 gallons) of propane? I did find a 20# BBQ tank will level a 3 story house. I am assuming being within 100 yards of a 3000# explosion is probably not a survivable event, but cannot find any info on that.

I did find this military explosive info. http://www.eur.army.mil/safety/files/Tactical_Explosives_Safety_Guide_Rev_6_Dec2011.pdf

On page 18 there is a chart with zones detailing the injuries and damage at various distances, but I cannot find the power of the explosion they are citing. I assume 3000# of LP gas would be similar in size to a military event.

Any help is appreciated. Thank you in advance.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence


9 replies so far

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tomd

2121 posts in 3604 days


#1 posted 12-05-2016 05:54 AM

I don’t know what you have in mind but I bet bells are ringing at Homeland Security right now.

-- Tom D

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TopamaxSurvivor

18086 posts in 3509 days


#2 posted 12-05-2016 05:59 AM

I hope they come and take care of the idiot who has the tank within 8 feet of a concrete wall sitting on top the ground without an embedded foundation. I can use all the help I can get! Think that qualifies as an IED? Or terrorist activity?

I thought about them when I was googling explosive and LP gas info ;-) Hopefully they crap their pants when they see it and go after the city for allowing it.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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JoeinGa

7721 posts in 1840 days


#3 posted 12-05-2016 01:51 PM

Ah ha, The infamous neighbor who built the concrete wall next to you? I remember your post about him.

Just goes to prove, you cant fix stupid.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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Alexander

193 posts in 2944 days


#4 posted 12-05-2016 03:06 PM

Bob, Try the Fire department, they may know.
The King county and others have requirements for the location of a propane tank. I think you can have smaller tanks next to your house but must be 3’ from a window. I think the county and others are more concern about the fumes than the tank blowing up.
I have a 500 gal. tank about 50’ from my house and it just sits on a concrete pad. Some tanks just sit on concrete blocks. Maybe tanks just don’t blow up on their own.

-- John at Sugarloft Mountain........Don't argue with an idiot; people watching may not be able to tell the difference.

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TopamaxSurvivor

18086 posts in 3509 days


#5 posted 12-05-2016 08:28 PM

Hi Joe, You certainly cannot ;-( Too bad ignorance is not the issue. It would have been over with 5 years ago.

Hi John, They are relatively safe. Have you seen the 3 or 4 gas explosions in the news around the Puget Sound area that have destroyed several buildings and killed a few people in the last year? The issue is a catastrophic failure of the concrete wall during a quake that ruptures the tank. I’m sure you have noticed steel on concrete makes sparks. If a 5 gallon (20 pound) BBQ tank can level a 3 story house, this 1000 gallon tank has the potential to level the neighborhood. The fire marshal told me the evacuation radius for an incident with a tank that size is 1/2 mile.

Unfortunately, I have been that route with the city. The guy in the Fire Marshal’s office passed away. I intend to go back with more info if I can find any. Seismic issues need to be addressed with the building department also.

The fire marshal told me he had never seen a tank earthquake strapped because it is not a requirement in the national code. The PNW is the only part of the continental US expecting a 9+ earthquake. Even the infamous San Andreas can only create an 8 as the fault line slips and slides. IMO, it would be prudent to have a higher standard here. The Richter Scale is logarithmic; therefore a 9 is 31.6 times the power of an 8. The Cascadia will be about 1000 times the Nisqually we had in 2001.

The tank is 8 feet from the wall. The city has certified an engineered improvement has been completed. Unfortunately, observed activity was not consistent with the magnitude of the project specified in the drawings and specifications. The owner did not care if the wall falls on his property according to the design engineer, so it (if it was really done to spec) is only to prevent falling on us. It is supposed to fall towards the tank as it is now designed.

Earthquakes have vertical and horizontal accelerations at the same rate of a falling object; 32 feet per second per second. Quake acceleration maxs out at 2.5 g (the force of gravity.) Starting at 1 g objects can be thrown into the air. The horizontal acceleration can move a vehicle 100 yards in 4 seconds according to OSU web page.

In 1971 in a 6.8 quake in San Bernardino, a parked fire engine with the brakes set left a tire mark on the garage door frame 3 feet high. I believe the odds of a catastrophic failure during the Cascadia quake are quite high. We are now in year 316 of an average 255 year cycle. The odds of the wall and tank remaining intact during the Cascadia are quite slim. Time is of the essence.

With what I have been able to find on the web about explosions and energy of materials, I believe the tank 1/2 to 3/4 full is equivalent to 40,000 to 54,000 pounds of TNT and anyone with in 100 yards is a fatality. Of course, serious injury and more fatalities will probably occur out to 250 yards. Lesser injuries and property damage beyond that perimeter.

I am hopeful that someone with explosives experience can verify or correct these assumptions.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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GeneR

151 posts in 1771 days


#6 posted 12-05-2016 11:24 PM

Topo,

How have you Been?

I think I might be able to help being that I am a fire alarm engineer and manager of an engineering team.

The code you are looking for is NFPA 58 that deals with flammable liquids storage and transportation.

NFPA 30 may be helpful as well.

NFPA 58 says the following:
| | Minimum distances | | | Water capacity per | Containers | Between container || above- | | | ground | Under- | Above- | containers | ground | ground |
|||_ | | |
Less than 125 gals(1)..... | 10 feet…..| None….....| None.
125 to 250 gals….........| 10 feet…..| 10 feet…..| None.
251 to 500 gals….........| 10 feet…..| 10 feet…..| 3 feet. 501 to 2,000 gals….......| 25 feet(2)..| 25 feet(2)..| 3 feet.
2,001 to 30,000 gals…....| 50 feet…..| 50 feet…..| 5 feet.
30,001 to 70,000 gals…...| 50 feet…..| 75 feet(3)..|
70,001 to 90,000 gals…...| 50 feet…..| 100 feet(3).|

Table H-23

Essentially a minimum of 25’ from their property line.

-- Failure is always an option. :-)

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GeneR

151 posts in 1771 days


#7 posted 12-05-2016 11:26 PM

Look at the Bold print the table didn’t paste well and you can find that code online.

NFPA is pretty much the world standard on all things fire related.

-- Failure is always an option. :-)

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TopamaxSurvivor

18086 posts in 3509 days


#8 posted 12-06-2016 01:32 AM

Thanks GeneR,

I have been great. Busy and enjoying getting paid for doing nothing ;-) How about you?

Thanks for your comments. Being an electrician, NFPA is the first place I looked.

The local fire marshal is citing a fine print footnote allowing 10’ since there is only one of that volume (over 500 gallons). I could probably contest the 2 feet, but it will not really matter in the big picture. It needs to move a long way and be earthquake strapped or the 35 tons of concrete needs to be moved away from the tank.

It is ironic that if Labor and Industries safety inspectors found a concrete slab 6 feet high standing on top the ground without lateral support or not marked as a no entry safety zone, I am absolutely sure they would shut the job site down and start writing citations, but in this city they allow it as a permanent installation without consideration of seismic standards or even wind load.

I found suggested safety rules by the gas association saying to keep heavy objects away from LP gas tanks, use common sense and contact local authorities. Seems to me those should be complementary, not mutually exclusive, eh? ;-(

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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GeneR

151 posts in 1771 days


#9 posted 12-06-2016 02:05 AM

i have been ok had a rough few years, got divorced and got custody of my daughter, but all is well now. It was hard getting back in the shop but I started turning again and building things here and there.
Was very dificult to get my motivation back.

-- Failure is always an option. :-)

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