combustible gas detection is a subsystem

Why can’t the combustible gas detector be directly connected to the fire alarm control panel?
The combustible gas detection alarm system, like the electrical fire monitoring system, is an independent subsystem of the automatic fire alarm system, and belongs to the fire early warning system. Combustible gas detector is a kind of preventive alarm which responds to single or multiple combustible gas concentration and realizes regional security monitoring. Generally, it is combined with combustible gas alarm controller and fire alarm to form a combustible gas detection alarm system.
The combustible gas detection and alarm system should be composed independently, and the combustible gas detector should not be connected to the detector loop of the fire alarm controller. When the alarm signal of combustible gas needs to be connected to the automatic fire alarm system, it should be connected to the combustible gas alarm controller. According to the requirements of the code, the combustible gas detection and alarm system is an independent subsystem composed of combustible gas alarm controller and combustible gas detector, but the combustible gas detector can not be connected to the bus of the fire detection and alarm system.

Why can’t the combustible gas detector be directly connected to the fire alarm control panel?
1.The meaning of alarm signal of combustible gas detector is different from that of conventional detector.
2.The protection area specific combustible gas alarm refers to its concentration exceeds the set threshold and it is an early warning signal, the alarm is uncertain of fire.
3.The working current of combustible gas detector is large, generally requiring dozens of milliamps, while the working current of heat and smoke detector is about 3mA. If the combustible gas detectors are connected to the bus line of fire alarm system, the current is too large for the controller, and the false alarm rate is high.
4.The combustible gas detector usually needs to be re-calibrated half a year, which affects the system work.
5.The working life of combustible gas detector is different from that of conventional fire detector such as smoke detector and heat detector, which needs to be replaced in 3 to 4 years.
When the output signal of the alarm relay of the combustible gas detector is connected to the fire alarm system through the input module, the operating state of the combustible gas detector can only be known on the fire alarm host, but the field gas concentration value cannot be known. Using the gas alarm controller, you can see the gas concentration value in real time, and even have the curve of concentration change, so it is easier to understand the trend of gas concentration in the field.