Actual facts needed about storm shelters being sucked out of the ground/doors failing

[GUN DOG]

Dennis 2011 Piedmont tornado housing addition Just north of Falcon lake. All but 4 homes destroyed
We had a large inground shelter outside with a flat steel door. You could hold 15 people easy sitting on the benches. It was all steel set in 8+ yards of concrete. The door had 3 cross bolts to keep it closed. When the tornado hit the tubine was sucked off & the door was vibrating so much that the bolts were vibrating out of the closed position, I went up the stairs & slid them back, they started to work out again. Not much tention to hold them. I installed a bungie cord to hold them in. This may have happened with some doors the vibration may have had the handles locks etc work loose

 

[Pulp]

Time for a bit of physics here.

1. There is no such thing as suction. There is only pressure differential. Air will move from high pressure to low pressure. As a tornado passes over a cellar, the pressure outside the cellar lowers. It does not "suck" the door off. The higher pressure inside the cellar blows the door open or off. You do not "suck" water through a straw, you just lower the pressure in the straw. The higher pressure on the surface of the liquid pushes water into and up the straw.

In the opening scene of "Twister", had the father just sat in the back corner of the cellar with his family and allowed the
the door to blow off, he'd have been in the movie much longer. When the door blew off he couldn't let go of the rope in time so he went with it. Wife and daughter remained safe in the back. So, if you find yourself in a cellar during a storm and the door starts shaking, let it go. Just go to the farthest corner from the door.

2. "Sucking" cellars out of the ground: the only way this would be possible is somehow air at higher pressure could get under the cellar. Or possibly water pressure from high ground water levels as mentioned are common in the Moore area. You absolutely have to have a higher pressure under the cellar than above it.

Disclaimer: I don't have a degree in Physics. I could be totally wrong. Just my way of seeing things, and playing with fans and vacuum cleaners etc. If my thinking is wrong, please feel free to correct me. Won't hurt my feelings, been wrong before and I'm still alive.

 

[dennishoddy]

Dennis 2011 Piedmont tornado housing addition Just north of Falcon lake. All but 4 homes destroyed
We had a large inground shelter outside with a flat steel door. You could hold 15 people easy sitting on the benches. It was all steel set in 8+ yards of concrete. The door had 3 cross bolts to keep it closed. When the tornado hit the tubine was sucked off & the door was vibrating so much that the bolts were vibrating out of the closed position, I went up the stairs & slid them back, they started to work out again. Not much tention to hold them. I installed a bungie cord to hold them in. This may have happened with some doors the vibration may have had the handles locks etc work loose

That could be a very good reason. Thanks for the input.

 

[dennishoddy]

Time for a bit of physics here.

1. There is no such thing as suction. There is only pressure differential. Air will move from high pressure to low pressure. As a tornado passes over a cellar, the pressure outside the cellar lowers. It does not "suck" the door off. The higher pressure inside the cellar blows the door open or off. You do not "suck" water through a straw, you just lower the pressure in the straw. The higher pressure on the surface of the liquid pushes water into and up the straw.

In the opening scene of "Twister", had the father just sat in the back corner of the cellar with his family and allowed the
the door to blow off, he'd have been in the movie much longer. When the door blew off he couldn't let go of the rope in time so he went with it. Wife and daughter remained safe in the back. So, if you find yourself in a cellar during a storm and the door starts shaking, let it go. Just go to the farthest corner from the door.

2. "Sucking" cellars out of the ground: the only way this would be possible is somehow air at higher pressure could get under the cellar. Or possibly water pressure from high ground water levels as mentioned are common in the Moore area. You absolutely have to have a higher pressure under the cellar than above it.

Disclaimer: I don't have a degree in Physics. I could be totally wrong. Just my way of seeing things, and playing with fans and vacuum cleaners etc. If my thinking is wrong, please feel free to correct me. Won't hurt my feelings, been wrong before and I'm still alive.

Your correct. The vents would equalize any pressure differential inside the shelter. The news anchors are the ones that keep saying doors were sucked off of shelters.

I deal with differential pressures every day in the power plant.

 

[Pulp]

I reckon I'm just being picky, kinda like "clips" and "magazines". Some things just bother me that way.

 

[Tampabucs]

Time for a bit of physics here.

1. There is no such thing as suction. There is only pressure differential. Air will move from high pressure to low pressure. As a tornado passes over a cellar, the pressure outside the cellar lowers. It does not "suck" the door off. The higher pressure inside the cellar blows the door open or off. You do not "suck" water through a straw, you just lower the pressure in the straw. The higher pressure on the surface of the liquid pushes water into and up the straw.

In the opening scene of "Twister", had the father just sat in the back corner of the cellar with his family and allowed the
the door to blow off, he'd have been in the movie much longer. When the door blew off he couldn't let go of the rope in time so he went with it. Wife and daughter remained safe in the back. So, if you find yourself in a cellar during a storm and the door starts shaking, let it go. Just go to the farthest corner from the door.

2. "Sucking" cellars out of the ground: the only way this would be possible is somehow air at higher pressure could get under the cellar. Or possibly water pressure from high ground water levels as mentioned are common in the Moore area. You absolutely have to have a higher pressure under the cellar than above it.

Disclaimer: I don't have a degree in Physics. I could be totally wrong. Just my way of seeing things, and playing with fans and vacuum cleaners etc. If my thinking is wrong, please feel free to correct me. Won't hurt my feelings, been wrong before and I'm still alive.

I wouldn't say you're wrong per say, but I would take issue with just saying get in the back of the shelter if the lid is gone. The issue is lids that aren't properly secured can get ripped off. The problem isn't necessarily getting "sucked up" into a tornado. Most everyone who is killing in a tornado is killed due to debris. Hence, the lid is off and debris flying at high rates of speed inside a small steel or concrete room isn't likely to end well. So, having a lid come off is a big deal if you ask me.

 

[Pulp]

Didn't mean to sound like I was minimizing the danger. You are absolutely correct about debris.

 

[Tampabucs]

Didn't mean to sound like I was minimizing the danger. You are absolutely correct about debris.

You made a good point about the lid technically not getting sucked off... I just wanted to point out the debris issue. I knew what you were saying.. no biggie.

 

[OkieGentleman]

This is my above ground installed last summer. 1/4 plate and extras by me.

 

[Tampabucs]

This is my above ground installed last summer. 1/4 plate and extras by me.

I like your setup. Does that safe room not have any interior bracing along the walls, or is it on the outside?