Siren Activation length during Tornado Warnings

[enigma1677]

Ok...I have always been very confused but interested in why some towns only blow their sirens for a very short time( 3-6 minutes) during a Tornado warning, where as other towns will blow them for the whole duration of the warning that is issued...ie on this video. http://www.youtube.com/watch?v=iYdukAE85gA

Someone said it is not good to let a siren go for any extended period of time, like 30 to 45 minutes. How true is that statement? I myself, think it is great that a town would sound them for the duration of a given warning, b/c in the case where they shut of after 5 minutes then the community thinks the danger has past and they start resuming normal activity and then ten minutes later the town gets mowed down by the tornado. It happened here last month on 11/15/06 in Montgomery, Al, the sirens went off for a total of 6 minutes then shut off, 15 minutes later the F-2 came screaming through and level a 5 mile stretch of town. All the people they interviewed on T.V., thought the storm had past b/c the sirens shut down. Is this something that is set by the EMA or just depends on local officials?

[FS T-Bolt]

Bartlesville sounds them for the usual 3 minutes...constant sounding of the sirens probably isnt good for them...

[SirenMadness]

The issue of the duration of a single siren activation for a signal depends on two main factors - the amount of money that you have at your disposal if sirens work their souls out for a false warning, and the amount of enthusiasm you have in the true safety of your citizens; you have to have one side dominate.
Some states prefer a short warning to be enough and economical in the case that their sirens survive, while other states think that they should give the longest possible warning, either for the best of safety, or for the fact that there are not many home-based warning apparatuses used at their homes. I think that most of the states that have their residents ensured of ownership of a home-based warning system are the ones that usually have their sirens as a last or main resort, blasting them for a pretty limited amount of time in a single signal. Sirens will most likely last very far beyond their indicated time of non-stop operation. What really matters is that the citizens are not lazy to abide by the rules of warnings and miss out. Three minutes, actually, is allot of time, though continuous duty throughout the designated warning is not bad. Extending a signal to around half of an hour is not necessarily an extremely good idea, because the siren should give out the message in at least three minutes, if not less, operating at an efficient level, reducing premature maintenance if the devastation does not damage the siren. Another factor that [might] determines the length of a signal is topography of a particular system, usually if the system is low on sirens. When i was very little, almost a baby still, they use to sound the sirens the entire time throughout an emergency, though they still last on the buildings that they were sounding on fifteen years before, today.

[jkvernon]

I know of several cities that will sound their sirens several times during a warning. Here in Columbus they'll set off the sirens for 3 minutes of alert then 7 minutes of silence then alert again and the cycle continues. Before eash alert cycle they make announcements over the sirens.

[Whelen Rules]

We blow our sirens for 3 min cycle, 3-5 mins off and then on again untill the warning expires or is cancelled.

[40V2T22]

Ours go off for the usual three mins. , but about 5 SECONDS later, they turn back on. It's a feature of our new system.

[jerrylovessirens]

We blow our sirens for 3 min cycle, 3-5 mins off and then on again untill the warning expires or is cancelled.

This is how our town does it with the RM-130's. Except the break is about 10 minutes. Gives them a little bit of cool-down time.

[Whelen Rules]

We blow our sirens for 3 min cycle, 3-5 mins off and then on again untill the warning expires or is cancelled.

This is how our town does it with the RM-130's. Except the break is about 10 minutes. Gives them a little bit of cool-down time.

We have Whelen Vortex sirens in my town so I guess they don't really need to cool down. I don't think the police department actually has a certain silence period in between activation times, it is just usually around the 3 mins on 3-5 mins off and then on again, our sirens are programed to go off for 3 mins even for tests. One time about 5 years ago in 2001 as a Tornado (f-0) at the time set down in the city they continually blew them just right after they shut down they would set off again.

[enigma1677]

So do electro-mechanical sirens actually heat up that much that they need a cool down period? I have a never heard any of the manufacturers say anything about overheating a siren. I would think they are air cooled. I understand that the electronic sirens dont need have a need for that because they are not motor driven.

[SirenMadness]

Not all electric motors are air-cooled, so they do sometimes overheat from excessive operation, though some motors just wear out, even though that will take a long time for something as simple as a siren.