Typical city gas detector in Europe

The 3 best city gas detectors 2023 | Complete buying guide

Every year there are thousands of domestic fires caused by gas leaks. This gas is highly flammable and is known to ignite at the slightest spark. Whether you use town gas or bottled gas, it is strongly recommended that you equip yourself with a town gas detector for your safety and that of your loved ones.

Our comparison for the year 2023

Comparison updated on 22/03/2023

Thinking of buying a 4-gas detector online and don't know which one to choose? Don't worry, we've got you covered.
In this article, we help you make an informed decision with the help of a clear and concise comparison. It will help you identify the product that best suits your needs, based on the opinions of many consumers.

1. City gas detector Ourjob

The best performer according to consumers

The Ourjob town gas detector is a device designed to detect a combustible gas leak in the air inside your home. When mounted on the wall, it alerts you with a visual and audible alarm if a gas concentration above the lower explosive limit (LEL) of 5 % is identified. Once triggered, the alarm will only be switched off when the gas volume falls below the 5 % LEL threshold.

2. Firlarm BRJ-502 city gas detector

Our favourite 

The Firlarm is a practical and easy to install gas detector. Installed in your kitchen or motorhome, it emits an 85dB audible alarm if the gas concentration exceeds the lower explosive limit of 3 %. Accurate in its measurements, the Firlarm is ideal if you want to protect your family from the risks of explosion and poisoning from a combustible gas leak.

3. Firlarm BRJ-502/E city gas detector

An interesting price/quality ratio

Just like its counterpart, the Firlarm BRJ-502/E is a city gas detector capable of alerting you to gas concentrations above 3 % LEL. The only difference between the BRJ-502 and the BRJ-502/E is that it is connected to the mains supply via a power cord and emits an 85 dB alarm.

How does a city gas detector work?

The town gas detector, as the name suggests, is a device used to measure gas levels in a given space. Like most air pollution detectorsIn addition, the system is equipped with sensors that can detect abnormal concentrations of existing gases in the surrounding atmosphere. If these sensors detect a sufficiently high quantity, they trigger an alarm so that people in the vicinity can evacuate.

What gases are detected?

In general, town gas detectors detect methane, propane and butane.

It's not rocket science | Gas


Methane (CH4) is the main component of natural gas and is used as a fuel in the production of heat and light. Widely used in the food industry and oil refineries, this gas is flammable. It also has the ability to substitute for oxygen, which increases the risk of asphyxiation. It must therefore be monitored with particular care, hence the importance of a dedicated gas detector.


Propane (C4H8) is used mainly for internal combustion engines such as those in boilers. In its pure state, this bottled gas is odourless and colourlessThis makes it undetectable without equipment. However, it is harmful by inhalation and can displace oxygen in a poorly ventilated area, causing suffocation for those exposed. Installing a suitable gas detector will enable you to detect a leak of this combustible gas in your home.


Butane (C4H10), also known as methyl ethyl methane, is a hydrocarbon that is refined from crude oil and natural gas. It is used as a domestic fuel for your gas cookers or heating and is usually stored in cylinders. Like propane, this gas is odourless and colourless and can cause health consequences (asphyxiation) when inhaled. At certain concentrations it acts as a central nervous system depressant and can also replace oxygen in an enclosed space.

Apart from these gases, other models of detectors are dedicated to the detection of more specific flammable gases such as ammonia, carbon dioxide, hydrogen, etc.

How to choose your city gas detector?

Man installing a city gas detector

Even if it is not compulsory to install a town gas detector in your home, it is strongly recommended that you have one, given all the protection it can provide. However, the choice of such a device should not be made lightly. To choose the ideal gas detector for your safety, here are some criteria to consider.

A question of gas

As you may have seen earlier, there are several types of gas that you may be called upon to use on a daily basis. Before choosing your detector, you need to know what kind of gas you are using. For example, you can choose between a natural gas detector or a butane/propane gas detector. In addition, there are also multi-gas detectors that work for all these types of gas.

The display

The display is one of the most important criteria to consider when choosing your detector. In addition to providing clear and legible information, your detector must be able to guide you through the display. After all, when the alarm sounds, you need to make decisions in a hurry. You will react more quickly if the detector tells you what to do. The choice of this type of device is therefore to be preferred.


In general, town gas detectors are connected to the mains. This makes them unusable in the event of a power failure. Fortunately, some models have a battery. In this case, it is strongly recommended to opt for a device with a good autonomy.

Fixed or mobile?

Toxic or flammable gas detectors usually come in two formats, namely fixed and portable. A fixed detector, as the name suggests, remains fixed in a specific place in the room, while the portable one can be moved around. Depending on the type of gas you are handling or its source, you should choose the most suitable model.

How to install a town gas detector?

The correct installation of the town gas detector is crucial for its functioning and speed of operation. In fact, for this installation, all you have to do is fix the detector to the wall following the instructions provided and then plug it in.

The location of your sensor varies depending on the gas and must be carefully assessed to avoid false alarms. Let's look at some tips for optimal installation.

  • Identify the installation area of your detector beforehand: fix your detector 1.5 metres away from your combustion source;
  • If it is a natural gas (e.g. methane), install your detector at the top of the combustion source, as this type of gas is lighter. For butane and propane, place your detector at the bottom, as these gases are heavier than the surrounding air;
  • Avoid placing the detector in enclosed areas, a damp room, over the sink, near the door or window or near an air extractor;
  • Do not attach your detector next to certain liquids such as alcohol, petrol, detergents, perfumes, solvents, thinners and others;
City gas flame lit in the dark

What to do in case of an alarm?

You've made the right choice by installing a gas detector and you're ready. So what happens if that alarm actually goes off? As with any other potential emergency, it is advisable to have a plan in place in case of a fuel gas leak. Write down what you would do, who you would call and how you would stay safe in this situation. Make sure your whole family knows the emergency plan and where to find it.

Here are the dos and don'ts in case your natural gas alarm goes off.

What not to do if your gas detector goes off:

  • Don't panic! These detectors are designed to activate before alarming amounts of gas accumulate. They are rated according to what is known as the 'lower explosive limit' (LEL). This phrase refers to the percentage of gas that has accumulated in your home. The detector is supposed to activate before it reaches a dangerous percentage, so if it goes off, you should still be safe.
  • Do not touch or handle any electrical equipment, including light switches. If necessary, you should use battery-powered torches. However, you should not unplug any equipment. Natural gas is highly flammable and a single spark can cause a fire.

What to do if your gas detector goes off: 

  • Turn off all gas appliances and smother any fire that might burn in your home: candles, fireplaces, cigarettes, etc.
  • Open all your windows and doors to let the gas disperse.