Electronic Point Detector

DTF sensors essentially are nothing else than extremely fast-responding NTC resistors. They have an extremely robust housing to protect the sensor against water and mechanical damages.  
In practice: the software in the control unit can adjust the alarm temperature of each single sensor individually. 

Mechanical point detectors.

Mechanical point sensors are working according to the principle of specific thermal expansion: If a fixed temperature is exceeded a signal is transmitted to the corresponding control unit.

After the fire is extinguished and the temperature had dropped down the point sensor simply resets.

Linear sensor / Temperaturesensor: 

FIREWIRE is the fire warning wire in the form of a stainless steel capillary with coaxially seated electrode. At an increase of temperature, both the resistance and capacity changes. If a certain threshold value is exceeded, the linear detector triggers the fire fighting system. The FIREWIRE may be installed in the area to be protected in such a way that it continuously covers the entire room.
FIREWIRE: The temperature sensor is produced in standard lengths of 150 cm to 600 cm. special couplings are used to connect FIREWIRE elements up to a length of 30 m.