Description

The multisensor construction is similar to that of the optical detector but uses a different
lid and optical mouldings to accommodate the thermistor temperature sensor. The
sectional view (below) shows the arrangement of the optical chamber and thermistor.
The signals from the optical smoke sensing element and the temperature sensor
are independent, and represent the smoke level and the air temperature
respectively in the vicinity of the detector. The detector’s microcontroller processes
the two signals. The temperature signal processing extracts only rate of rise
information for combination with the optical signal. The detector will not
respond to a slow temperature increase – even if the temperature reaches a high
level. A large sudden change in temperature can, however, cause an alarm without
the presence of smoke, if sustained for 20 seconds.
The processing algorithms in the multisensor incorporate drift compensation. The
control panel must not have a drift compensation algorithm enabled.
The sensitivity of the detector is considered the optimum for most general
applications since it offers good response to both smouldering and flaming fires.