Fixed Gas Detection System-Everything You Need To Know

A fixed gas detection system is installed to provide continuous area and personnel protection around the clock.

These detection systems are designed to alert workers of the potential danger of poisoning by toxic gas exposure, asphyxiation due to lack of oxygen, or explosion caused by combustible gases.

What is a fixed gas detection system?

A fixed gas detector is a safeguarding system that constantly monitors a location due to the excess levels of gases. 

Is a fixed gas detection system necessary?

Fixed gas detection systems are often required to protect facilities by the insurance companies that underwrite them and even by some standard electric codes.

By protecting the facility, they also protect the lives of the people working there.

What are the Components of a Fixed Gas Detection System?

A fixed gas detection system consists of 3 parts: the sensor, transmitter, and controller.

The sensor


The sensor is the actual device that senses the gas. Many sensors, such as catalytic beads, infrared, and electrochemical, are used in gas detection.

Sensors typically last 2 to 4 years but can last longer or shorter depending on the application’s nature.

Solid-state and Infrared sensors typically last much longer, and it is not uncommon for them to last 5 to 10 years or more.

Most fixed sensors can work as standalone units, but it is better to connect them to a transmitter and a controller if you want to integrate them with other systems.

The Transmitter


Most sensors require a transmitter to amplify the signal and convert the gas sensor signals into a standardized output, such as 4-20 mA, Modbus, and HART, for transmitting the signal to a controller.

The transmitter is usually close to the sensor, and zero and span adjustments must be done at the transmitter.

Most transmitters are operated from 24 VDC and utilize 2 or 3 wires. In general, even if a sensor can be used without a transmitter, the use of a transmitter is often preferred for distances over 300’ to 500’ to simplify the calibration effort.

In general, even if a sensor can be used without a transmitter, a transmitter is often preferred for distances of 300’ to 500’ to simplify the calibration effort.

The Controller

The Controller

The controller is the device that receives and interprets the signals from the sensors and sensors/transmitters.

The controller typically provides a readout of the gas concentration, audible and visual alarms for dangerous gas levels, and generally alarm relays for activating an external alarm or other action.

In some applications, it is preferred to send the transmitter signal (such as 4-20 mA) directly into a

PLC (Programmable Logic Controller) or other similar control devices. In this case, the PLC activates the alarm conditions and relays, and a “Gas Detection” controller is not necessary.

FAQ: Fixed Gas Detection System

What is the difference between fixed and portable gas detectors?

Fixed Gas Detectors: Ideal for continuously monitoring specific areas or zones within facilities where gas hazards are present.

Portable Gas Detectors: Suitable for applications requiring mobility, such as confined space entry, leak detection, maintenance activities, or outdoor monitoring.

What are the two types of gas detection systems?

Gas detectors come packaged into two main form factors: portable devices and fixed gas detectors.

Final words

That is it. Those are the three main components of a fixed gas detection system. Thank you for reading.



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