a mile outside of Casselton, North Dakota
Correct me if I'm wrong but I think Michael Eyer, the retired Oregon hazardous materials train inspector, got it wrong when he said:
Federal regulators could impose a cap on the amount of flammable gas allowed in the oil. "You would have a fire," Eyer said. "But you would not have the mushroom cloud in the sky."
Wrong, I believe, because the fireball explosion is usually caused by a Boiling Liquid Expanding Vapor Explosion or BLEVE which can be caused by intense heat.
Although
your water heater has no volatile gases, it will explode like a rocket
and go through your roof if the thermostat doesn't shut off the heat
below the boiling point. See it here.
As I understand it . . .
When a tank car is ruptured, the vapors find a spark and carry ignition back to the liquids.
When
flames surround an intact tank car, the pressure builds beyond the
bursting strength of the tank. If the tank held only water, the tank
would still explode but would not add extra fuel.
The Lynchburg VA explosion a year ago didn't look like a BLEVE to me, although it was loud like the backfire of a motor cycle.
The
lower the vapor pressure, the lower the probability of ignition, but
once a fire has started, other cars can BLEVE if they get too hot.
Thus, fire-fighters aim their hoses at the intact tank cars to prevent a BLEVE.
One
of the firefighters involved with the ethanol fire in the picture is a
city council member in Hood River and he spoke to us at the oil forum we
had in Washougal. He said an oil train fire would overwhelm the
Portland Fire Department.
My guess is that even
a vapor pressure of 4 could lead to ignition. While heating a
tea-kettle the other day, I lifted the kettle before it started
to boil. The sloshing of the water pushed out the vapors and made a
whistle.
Here are the best links I've collected over the last month.
Sources
Feds predict 10 serious oil train derailments per year
Refiners sue BNSF for surcharge on old tank cars.
cpc 2.Even the newest-safest tank cars that exceed U.S.
standards are inadequate.
Phase out CPC 1232s faster
3. Canadian
Pacific Railway wants to stop hauling crude oil, because the risk is too great.
4. Vapor Pressure
6. Lower speeds to 12 mph
7. Ultrasound crack detectors fail, DOT
112 tank car fails – Gainford Alberta
Don Steinke
Vancouver USA
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