How to choose the right type of gas detection
There is a broad range of gas detection equipment, and many items may seem to be identical. But if we take a closer look, each device has clearly-defined functions and characteristics, offering certain specific benefits. For that reason, you need to define your need(s) before selecting the gas detector that suits you best.
Good to know: contrary to popular belief, gas detectors are not classified as category 3 PPE, but they are important because they warn operators of a potentially lethal risk. Consequently, you should never choose a gas detector lightly. We offer you a set of good practices to help you choose the right detector for you.
Assess the gas risks
The first step is to know and define your risks. All companies are obliged by law to carry out a risk assessment to identify any potential hazards. These hazards include gas-related risks.
A gas is a swarm of molecules that move randomly and chaotically, bumping into each other and with whatever else happens to be in their way. The most obvious example is the air around us, which is made up of different gas molecules. So gas is everywhere, and poses many dangers. They are classified into 3 risk categories:
- Risk of fire and/or explosion such as the presence of flammable gases (methane, butane, propane, etc.)
- Risk of poisoning/intoxication such as a leak of one or more poisonous gases (carbon monoxide, hydrogen sulphide, carbon dioxide, chlorine, etc.)
- Risk of anoxia/hyperoxia such as an insufficient or excessive oxygen supply (oxygen can be consumed or displaced by another gas).
If one of these dangers is identified, gas detection is one of the ways in which you can reduce those risks : Asphyxiant, toxic, flammable gases.
Identify the main objective
The second step when acquiring gas detection equipment involves identifying the objective. Once you have defined your objective, you then get a clearer idea of the best solution. There are various reasons to be considered, including the need to:
- Obtain management reports for a site manager (notifications via remote or off-site warnings, event-related data, etc.)
- Be in conformity with the regulations for the legal aspect
- Comply with the special conditions imposed by insurers
Whatever your main objective, remember that a gas detection solution exists to protect human life. Determining your reason – whether it be legal, for insurers or site managers – allows you to decide which type of fixed or portable gas detection you need, and which functions and characteristics are most tailored to your objective.
Ask yourself the right questions
Next, in order to select the right equipment, you need to ask yourself the right questions, in other words:
- What gases need to be detected and where do they come from?
- In what places and environmental conditions will the detection system be used?
- How simple to use do they have to be for operators and staff who carry out routine servicing?
Your answers to these questions will have a direct impact on the solution proposed and the costs related to the equipment offer and maintenance.
Identify which gases need to be detected and where they might come from
A perfectly-adapted gas detection solution must be able to detect the presence of a specific gas and trigger a warning before dangerous concentration levels are reached.
It is important to remember that the end user is responsible for identifying all the potential dangers. The risk assessment provides the means of identifying the gases to be detected. What do we do once we have that information?
Identify the type of risks you face (flammable, toxic and/or asphyxiant gas) in order to determine the type of sensors
Determine the relative concentration levels that could be dangerous in order to define the alarm setpoints, the position of the sensor for fixed gas detection systems, etc.
Identify the potential sources of a gas leak in order to determine the number and location of the sensors required for a fixed gas detection system. On the other hand, if the sources of leaks are unknown, it is better to use portable gas detectors.
Common sources of gas emissions include:
- Natural emissions such as methane and hydrogen sulphide from waste decomposition
- Leaks from supply pipes or a natural gas storage tank or pipes
- Gases produced when a fuel is burned, such as carbon monoxide from exhaust pipes and boiler discharge pipes
- Gases produced by a combustion process such as solvents in the printing and coatings industry
- Emissions from production plants such as ammonia from a refrigeration plant or nitrogen from a nitrogen production plant
Take the environmental conditions into consideration
Gas detectors are fitted with sensors that are sensitive to their environmental conditions. There may be repercussions on their performance, accuracy and reliability. The temperature, relative humidity and pressure level observed on site all therefore have a direct influence on the type of equipment to be chosen.
Other factors such as potential variations resulting from a production process itself, fluctuations depending on the time of day (day or night) or seasonal variability can also have an influence of the type of equipment deemed to be most appropriate.
It is important to decide whether the equipment will be used inside or outside, because this has a big impact on the choice of protection rating for the housing:
If it is placed outside, the detector will be exposed to the wind, rain or salt spray. It needs to be able to withstand the corrosive effects of these types of environment.
Inside, less sturdy housing is sufficient, but the degree and types of exposure to water (water jet cleaning) or dust (dirt) need to be defined.
Determine whether there are any other climate conditions likely to influence the choice of equipment, such as detection technology.
Example 1: hydrogen sulphide has corrosive properties, and other atmospheric components may have a damaging effect on the reliability of some types of detection technology.
Example 2: Silicone-based substances have inhibiting properties on detection technologies that use catalytic bead sensors.
Define the safety level required for these equipment items in certain dangerous areas. Depending on the area, you will need to acquire a device with adequate ATEX certification (Area O: Ex 1G, Area 1: Ex 2G, Area 2: Ex 3G, etc.)
Define the product functions
It is essential to adopt an overall approach when deciding what functions your equipment needs. Products vary greatly, and the more functions there are, the higher the cost, inevitably.
Here are a few examples of functions that offer added benefits for users, meaning that one product will be more appropriate than another in a given case:
- Display of local units of measurement
- Presence of a local user interface
- Software compatibility
- Number of relays and outputs required
- Possibility of connecting remote sensors
- Integrated diagnostics
- Hot-swappable cartridges
- Lock out / tag out procedures in response to events
Opt for equipment that is easy to use and maintain
Ease of use:
The stakes are high, because the goal is not simply to acquire gas detection equipment in order to ensure conformity with the law or a standard, or for insurance purposes. The ultimate goal is to protect operators: a gas detector that is simple to handle is more likely to be used by operators.
Detection equipment downtime can cause a decline in production. That is why you need to opt for solutions that offer the possibility of replacing sensors quickly, simply and safely.
The choice of gas detection technology is another important factor, because it has an impact on maintenance, for example in the case of a sensor for measuring the explosion risk:
- Catalytic bead sensors: do not operate safely in failure conditions and require very frequent maintenance tasks
- Infrared: reduces the number of routine maintenance tasks but is more expensive to buy.