With the detector types FAH-425-T-R, it is possible to set one of the sensitivity classes listed above in line with planning. In the sensitivity classes A1, A2S and BS, the FAH-425-T-R is operated purely as a thermal maximum detector. In this case, the detector does not activate at below 54 `b0C in class A2S, and not below 69 `b0C in class BS. The sensitivity classes A2S and BS are therefore particularly suitable for applications where higher temperature rates-of-rise occur over a longer period, e.g. in kitchens or boiler rooms. The sensitivity classes A1R, A2R and BR indicate that the thermal differential unit is active in addition to the thermal maximum unit. These sensitivity classes are especially well-suited for use in unheated buildings where the ambient temperature can vary greatly but high temperature rates-of-rise do not last long. The thermal differential unit enables class A1R/A2R detectors to respond at T<54 `b0C and class BR detectors at T<69 `b0C. The selection of the sensitivity class also depends on the installation height of the detector. Furthermore, the expected application temperature must be taken into consideration.
