Are all three-phase (rotor) sirens made to spin either way?

[Robert Gift]

The 2t22 rotors are made to spin either direction.
Just depends upon how the motor happens to be wired.
Reverse any two wires, and it will run the opposite direction.

[AllSafe]

All except for a few ACA and Decot sirens which have curved vanes; they were made to run in a specific direction, otherwise they would not be as loud.

[JasonC]

The blower motor of a 3 phase T-bolt has to run in a certain direction, but not the rotator motor. You can see an arrow on some ACA sirens to point the direction of correct rotation.

[Gents']

I did consider this when running the Gents' and ran it both directions. There was no difference in sound output so the rotors must be made to run either way.

[Conky 2000]

The blower motor of a 3 phase T-bolt has to run in a certain direction, but not the rotator motor. You can see an arrow on some ACA sirens to point the direction of correct rotation.

Yes, the Penetrator near me has a curved arrow on the inside lip of the horn saying "(curved) <--------ROTATION"

[Robert Gift]

Surprised that they did not make the rotor more efficient by making it directional.
But direction requires that the electrician reverse two wires if necessary.
Maybe they think some will not go to the trouble and a siren rotor will be turning backwards.
I am such an idealist, I have the 2t22 turn counterclockwise to gain assistance from the Coriolis Effect!

[Gents']

heh - I'd love to know how much of a difference that makes! You get my green vote.

[AllSafe]

It doesn't matter which way you wire the three legs on a 3-phase motor. If you wire it wrong and it runs in the wrong direction, just reverse any two legs.