From time to time you can hear it in the news: a gas leak in an apartment building or a house, sometimes even followed by an explosion. Sometimes this occurs due to activities or repairs, but it can also occur due to old age or improper maintenance of the installation. Gas leakages will not only occur in houses, but also in the industry. In some cases, the gases that leak here will be even more explosive or toxic. But how do you recognize these leakages before it is too late?
The answer might be easy: just order a gas detection system and place it somewhere. However, what type of gas detection system do you need? And where do you place the sensors? In this blog I will provide you with 6 steps on how to determine where to place your gas detection sensors.
1. Identify the most likely gas leak/release points
To rapidly determine whether a certain gas is leaking, you want to detect it near to the release point. However, it will be too expensive to cover the installation completely with gas detection systems. To find the right balance, the most likely gas leak/release points have to determined. One of the methods which can be used for this is a HAZOP (HAZard and OPerability) study. This study structurally reviews an installation, by dividing the installation into smaller parts and determining what can go wrong with the use of certain deviations. For example: what can cause a high pressure in the installation. When the causes are determined, the consequences determined. In case the cause is a release of gas from a certain part of the installation (for example a flange connection), then this is a place where you want to have your gas detected.
2. Identify whether these installations are indoors or outdoors
Several environmental conditions can influence your gas detection and influence how well your sensor performs. Environmental conditions are easier to control when indoors than outdoors.
3. Evaluate the relative densities (with respect to air).
The weight of each type of gas differs. Therefore it is important to know the relative densities with respect to air. Gases which are lighter than air, will go up and gases that are heavier than air will go down. For example: Methane (CH4) is lighter than air. When you place your sensor lower than the leak source, this sensor will never measure the gas, because it will directly go up. This sensor should be placed higher than the source.
4. Evaluate wind directions and air flows to judge likely flow of released gas
The wind direction and velocity also has an influence outside, but inside the ventilation system can determine the air flow and direction. All these factors have to be taken into account. For example, if the installation is inside the building and the air is flowing from north to south of the building. When the sensor is placed near the leak, but on the north side, the gas will not be detected.
5. External factors
What sort of facilities are just outside your installation? It is possible that gas flows in that direction and therefore adds risks to the surroundings. For example another installation or a residential area could be located nearby.
6. Local law and regulations
In some countries, additional requirements can be made for gas detection systems. Some countries oblige two sensors instead of one to detect certain gases. In addition, the concentrations allowed for certain gases can be lower than the safe exposure limit.
There is more to consider when ordering a gas detection system. For instance the type of instruments and how to maintain or calibrate the gas detection systems has to be decided on, Maximum allowable concentrations of the gas and the follow up actions when the gas detection is activated have to be determined.
If you need help in determining the gas leak/release points or other questions about gas detection systems, please call me: Jessica Vlessert – van de Vosse: +31 6 55 37 13 56
Do you have any other comments or questions, please leave them below!
For more information about Hazard and Operability Analysis and other risk studies, take a look on our website.