Fixed and Portable Gas Detectors: All You Need To Know

Generally speaking, gas detectors are mainly divided into two categories, namely stationary and portable. Both types utilize a variety of gas sensors to detect gas or vapor hazards. Both types have their own advantages and disadvantages. Therefore, it is extremely important to understand the nature of the gas or vapor hazard you are trying to mitigate in order to determine the most appropriate detection solution. Risk assessment is always the starting point. Mitigation will take several forms – gas detection is one of them. At this point, it is usually best to let the gas testing company find a suitable solution.

gas detectors
Fixed Gas Detectors

Permanently installed in the field, fixed gas detector for continuous monitoring of the environment. Fixed detectors work similarly to fire and smoke alarms. Detectors for the target gas are deployed on site and connected to the control panel. The controller monitors the detector and sets alarm conditions based on gas levels. Trigger an audible and visual alarm at a basic level to alert personnel. More advanced installations can alert other monitoring systems, activate and disable systems, log and trend data, connect to cloud-based systems, and more. This is one of the main benefits of a stationary gas detector over a portable one.

Fixed Gas Detector

Fixed detectors will monitor a limited area/volume around the detector, typically a 5M radius. This means placement needs to be carefully considered for best performance. Detectors may be diffusion types or pump (aspirated). The right choice is application dependant.


24/7 continuous detection of the environment

Can perform executive actions for example shut off gas supplies and provide site-wide alarms

Remote alarms possible including GSM text and email alerts and cloud monitoring

Clear unambiguous alarms if specified correctly

Events can be recorded for HSE requirements

Data can be logged for trending


Accurate detection is limited to gas that diffuses into the sensing inlet – requiring strategic placement of detectors

Capital installation cost can be expensive depending on the amount of equipment required

Demand constant power supply

Requires regular service checks – just like a fire alarm system

Portable Gas Detectors
Portable Gas Detector

Portable gas detectors are designed to be carried or worn clipped to an item of clothing. They form part of a person’s PPE. This category of detector is a life safety device designed to provide alarms to the wearer when target gas levels exceed safety limits. They should not be mixed up with handheld gas leak detectors or analysers which are not intended as life safety devices. They can screen for hazardous species that may enter an operator’s breathing zone or be used for confined space entry testing. Portable gas detectors can be just for a single gas or may monitor for up to seven gas types. They may be diffusion-based or be pumped depending on the application. Portable gas detectors are intended for use where it is impractical to fit a fixed system.


Easily deployed

Directly protects an individual

Can be integrated with man down or lone worker alarms by GSM

GSM linked units can be tracked centrally and monitored remotely


No automatic responses

Operators must be trained

Requires daily bump test

Does not provide 24/7 monitoring

Only protects a single user

The user is wearing the unit and so is in the hazard when the detector alarms

Has to be sent for calibration meaning cover units are required (multiple sets)

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