HLS siren

[Rory Buszka]

The HLS does have the ability to run only the engine, whose alternator charges a set of deep-cycle batteries. I imagine that there is enough hysteresis built into the control system for the compressor that the engine does not start and stop every few minutes. The rate at which the compressor charges the tank should be relatively slow, given the two-stage compressor (which is different from a single-stage, two-cylinder compressor), so it may run for nearly 20 minutes to bring the tank back up to pressure. The volume of air that can be moved by the compressor is relatively small since it has the two-stage design to operate into high pressure.

[Robert Gift]

And the HLS would most likely blow away the 2001. And that?s the resion for all the valves compressors and other doohickes.and the 2001 is a littel high pitch for my taste.

Yah, buthink of all thexpense and complication and care and maintenence?

Better to have two simple moreliable 2001s than ONE more powerful siren.

[Jim_Ferer]

There's always been a debate over using one big siren compared to more smaller ones. The T-135 is the champion of the big siren concept. It's hell on people who live close to one but in theory carries much farther.

Personally, I come down on the side of smaller, more dispersed sirens. Here's why I do:

* If a big siren goes down, you've lost a larger area than if you lose one smaller one.

* Building obstructions are harder on big sirens, since you have one point source instead of several sources.

* The inverse square law. Any radiated energy, like light or sound, decreases as the square of the distance. Double the distance, and the sound is reduced to one fourth of what it was.

* People living close to one are less likely to be traumatized when the things go off for tests and so on. If somebody tried to put a T-135 at my kids' school I'd pitch a major female dog.

the pros of a big siren are simplicity and cost. One siren to find a place for, one siren to buy (more than one smaller one, but less than three or four) and only one siren to maintain. An HLS must cost a fortune. I bet you could buy and install another siren for what it costs just to install an HLS.

I think big sirens are probably best in industrial areas or suburbia, where there's lots of low buildings all spread out.

Bringing it back to the HLS, I doubt there's many being made now. I could buy a bunch of E57s for what one pneumatic one cost, and, being so simple, they probably cost less to maintain. I can put one in any dead spot I happen to discover.

[Robert Gift]

Yes, as much as I'd like onenormously powerful siren, hate to admithat many smaller sirens is better.

The inverse square law is anothereasone giant siren is not as effective.

I was told Yantai, China had one siren on West Yantai Mountain.
"It is merely a symbol." I declared.
For a city that size, ONE siren was entirely insufficient.
I accused the Chinese authorities of being completely incompetent
-as they are in so many other areas.

At least I expected the siren to be supercharged and powerful.

Turned out to be a disappointing single tone presumably three-phase motor ([]D< similar to one seen in http://www.lksos.com

When they performed their annual test August 15th at 9:30 a.m.,
the Yantai Mountain siren I "stocked" did not operate!
But I discerned at least 4 other sirens.
One was only 0.40 miles west of my siren.

I was wrong abouthe authorities.
The one west was on the first level of a two-level dome atop a 7-story building.
Should have been on the second level, or better, right out in the open on the roof.