These units take and utilize the best of fixed and rate of rise features to react quickly to a fire yet not false alarm like other units.Because they sense the surrounding air no matter the fires growth
You will find them where fast hot fires develop very quickly like Engine rooms on Boats Boiler rooms , both liquid and vapor Gas fueling, handling and production facility's and Chemical Plants
There hermetically sealed against the elements and utilize a self resetting Bi metal element which allows it to be tested multiple times unlike one time use fixed temp sensors
Needless to say there not cheap around $100 each compared to a $20 heat you find in a home or business but when you need a rugged well built quick reacting fire sensor this is it.
The units also have the advantage of being able to be used in hazardous and explosive environments as well as all weather.
have a high risk facility which needs fire protection this is what you need to install.