HLS siren

[Robert Gift]

There is another video on youtube, where the videographer is really close to the siren, and when it shuts off and winds down, the air stays on until the rotor stops. Is the time delay of the air shutoff adjustable?

Being part German myself, and knowing how practical they are,
I'd be surprised if they didn't haveverything shut off athe same moment.

They would not care enough about having a nice windown sound to bother to place anotherelay to shut off the air later.*

My guess it is residual stored in the reservoir blowing off.
They WOULD have a good respectable reservoir!

* just like their steam locomotive whistles are crap - nothing like wonderful American locomotive whistles. So easy to do, buthey didn't bother.

[Robert Gift]

Nussdorf? Is there a mental hospital nearby?

Good one, Daniel!
LOL

[SirenMadness]

I think that their reasons for the cut-off of air at the wind-downs is to make the wind-down more distinguishable, and to use air as efficiently as possible. When any HLS variant runs off of air stored in its six-thousand-liter air-tank, it cuts off the air at the wind-down, because a break in sound would very similarly be distinguished to a wail. Also, when having air pumped to the chopper by the compressor set itself, there looks to be a clutch to control the transfer of energy from the diesel-engine to the compressor mechanism.

[Robert Gift]

I think that their reasons for the cut-off of air at the wind-downs is to make the wind-down more distinguishable,

Sorry, I don't understand.
Why would windown sound matter?

and to use air as efficiently as possible.

Well, I could understand that. "Efficiency is all."

When any HLS variant runs off of air stored in its six-thousand-liter air-tank,

Why such a huge tank?
They keep it pressurized 24/7 until the nextest or alert - whichever comes first?

it cuts off the air at the wind-down, because a break in sound would very similarly be distinguished to a wail. Also, when having air pumped to the chopper by the compressor set itself, there looks to be a clutch to control the transfer of energy from the diesel-engine to the compressor mechanism.

Sorry, I don't understand whathat means.
They divert energy from pumping air to the reservoir
to spinning the rotor?

Thank you,

[SirenMadness]

The wind-down sound would matter because it is what gives the general wail tone its clear characteristics.

Yes, the tank is big. This is so that the HLS can do many separate alerts when the compressor isn't working; the compressor would be used for normal operation. The tank is only pressurized when unacceptably low pressure of air is within the tank.

No. The chopper-motor is spun by an electric motor; the diesel-engine just gets disconnected from the compressor mechanism, so as to not be restarted after every second.

[Robert Gift]

The wind-down sound would matter because it is what gives the general wail tone its clear characteristics.

I don't see how that matters. Aren't all windowns the same?
(Justhatheirs does not windown very far before spinning up.)

Yes, the tank is big. This is so that the HLS can do many separate alerts when the compressor isn't working; the compressor would be used for normal operation. The tank is only pressurized when unacceptably low pressure of air is within the tank.

Oh. The tank provides pressure for their weekly(?) tests?
They do not run the engine for these shortests.
Thengine would never attain operating temperature, which is bad for thengine?

Then, after enough tests, when the pressure drops to a preset minimum, the diesel operates to bring it up to full charge for another number of tests?
Also, the reservoir is backup storage ifor some reason the compressor engine fails to start?

No. The chopper-motor is spun by an electric motor; the diesel-engine just gets disconnected from the compressor mechanism, so as to not be restarted after every second.

So, during an actual 15 minute real alert, the engine would be running?

Well, this now makes more sense. Don't run the engine for just a few minutes, but still check out the siren.
Does thengine also produce electrical power to run the rotor motor,
shouldomestic power fail?

Thank you, Peter.
Please correct me if I have anything wrong.

[SirenMadness]

You're welcome, Robert.

Yes, I know that wind-downs are all generally the same. But I guess that a drop in sound volume is more noticeable than a drop in sound pitch, which might be the reason for this feature. But I don't know for sure, though.

Yes, the tank could provide the air for tests, depending on who might do that. They could run the engine for short tests, just to save air, or even test the engine itself.
The engine is a fifteen-horsepower, two-stroke engine built by Deutz. It is pretty dependable. Also, the engine is inside a compartment, thus bearing a small amount of operational conditions from the environment.

When the pressure does drop to an unwanted level, the compressor system will pump it up to at least the minimal required pressure.
It would seem that the tank is for emergency situations, because there wouldn't be a clutch for the engine and compressor mechanism is all you were to do would be to shut the engine off after about an entire minute!

Lastly, the engine would be running for an alert at which the engine will not fail to work.
The engine does not provide direct electricity for the siren, but both parts twenty-four-volt battery, with eighteen cells, each cell producing (1.333) volts.

[Jim_Ferer]

Any air system has to have a plenum, a "stock" of air to draw on. If all the air was just that in the piping the performance of anything powered by air would suffer greatly.

[Robert Gift]

You're welcome, Robert.

Yes, I know that wind-downs are all generally the same. But I guess that a drop in sound volume is more noticeable than a drop in sound pitch, which might be the reason for this feature. But I don't know for sure, though.

I didn't realize that dB drop was intentional.

Yes, the tank could provide the air for tests, depending on who might do that. They could run the engine for short tests, just to save air, or even test the engine itself.

I thoughthey would NOT wanto run thengine for shortimes. Bad for engine.

Also, the engine is inside a compartment, thus bearing a small amount of operational conditions from the environment.

What does that mean?

When the pressure does drop to an unwanted level, the compressor system will pump it up to at least the minimal required pressure.
It would seem that the tank is for emergency situations, because there wouldn't be a clutch for the engine and compressor mechanism is all you were to do would be to shut the engine off after about an entire minute! :wink:

So, the clutch allows thengine to start?
Otherwise load from compressor may not allow it to start.
Then, when up to pressure, clutch releases and engine stops?

... the engine would be running for an alert at which the engine will not fail to work.
The engine does not provide direct electricity for the siren, but both parts twenty-four-volt battery, with eighteen cells, each cell producing (1.333) volts.

Are the batteries charged from solar cells?
Seems thengine should charge the batteriesince they already have an engine.

I assumed the tank held pressure to allow immediate sounding of the siren
even if the engine failed to start. Also, to allow tests without running the engine for short periods which are bad for the engine.

So, someone has to visit all these sirens and fill fuel tanks?
Would have to be low temperature diesel so that it doesn't gel in winter.

Thank you,

Robert

[KnightFox]

Ever possibly think RObert that it might be a engine that can run on Natrual gas or propane? Then that way it can take what it needs from the main gas line.