If gas detector had been separated, there would be the 2 important part. Sensor and transmitter. So, what is the sensor and the transmitter? In simple terms, the sensor is the main and significant part of the detector that detects/response to the compounds in the environment via using different sensing technologies.

However, transmitter translates the data gotten from the sensor to electrical values that electrical systems might recognize. So, the sensor plays a key role first when it comes to gas detection.

There are various sensors used in gas detectors to detect combustible gases and vapours such as Pellistor(Catalytic), Infrared, semi-conductor, PID etc. Among these sensors Pellistor and Infrared are the well-known and used sensor in industrial applications but which one should be chosen Pellistor or Infrared?

1 - Pellistor Sensor
Pellistor gas sensor is a device used to detect combustible gases and vapours. There are two beads inserted to the Pellistor sensor. First one for measuring the gas and the second one is for reference values. There is a platinum coil wire covered with catalyst inserted inside to bead. When combustible gas is present the temperature and resistance of the bead increases in relation to reference bead. This resistance difference can be measured. So, this the way that Pellistor sensor used to measure the combustible gas and vapours. Additionally, because of the catalyst and beads, Pellistor sensor is also known as a catalytic sensor.

2 - Infrared Sensor
The infrared gas sensor uses IR lights to detect target gas. IR lights are generated by two emitters inside of the sensor and these IR lights are moved continuously. They are deflected by a mirror inside the sensor onto a photo-receiver. When target gas is present a particular wavelength will be absorbed by target gas. Each ray has equal intensity. So, difference intensity resulting between the measurement and the reference ray is monitored gas concentration.
Relations with the environment, temperature range and response time are the main things that considering when it comes to deciding sensor.