The shunt-trip C/Bs for a range hood are meant to shut down the electrical supply to anything under the hood and the air handling for the hood in case of a fire. Generally, there is a contact in the fire suppression system that will CLOSE when the temperature threshold is reached, which will energize the shunt (really no more than a magnetic solenoid) in the C/B and open the circuit. If it's acceptable to the AHJ, this can also be accomplished by routing your circuits through an electrically held contactor which will be controlled by a contact that will OPEN when the temp is reached. This is usually easier,it takes up less breaker space, and doesn't rely on the power to the controls being on to shut the system down.
Another method that can be used if you just have to control a motor that has a mag starter is to run the control circuit for the mag through the temp contact so it will open upon the sensing of the fire.
[This message has been edited by electure (edited 06-17-2001).]
I have not run into a shunt trip used for fan shutdown. We use them for elevator service when the elevator shaft is sprinkled.
All the fan shutdowns I have seen are wired into the fan controls. It would certainly do the job, though.
In addition to what electure has to say, some municipalities may require this system to be tied into the fire protection circuits which may inform local fire departments of a fire.