Methanegas detector is also known as flammablegas detector。 It is mainly used to detect the content of methane gas in the environment. When there is a leak in the environment, the concentration value can be displayed in real time and an alarm can be given. When the staff is in use, they sometimes encounter the detector showing a concentration of 100. At this point, what is the concentration of methane leaking? Is it dangerous? The following is a detailed answer for you.
1. LEL is combustiblegas detectorunit
In general, methanegas detectorThe display unit is %LEL, which is the lower limit of explosion. The mixture of flammable gas (steam) and air will not explode when it encounters a fire source at any concentration, but can only explode when encountered in a certain concentration range. The range of flammable gas concentration that can be exploded when exposed to a fire source is called the explosion limit of flammable gas (including the upper and lower explosion limits). Lower Explosive Limit: The lowest concentration of flammable gas in air that can cause flames to spread or explode, expressed in %LEL. Explosive Limit: The highest concentration of flammable gas in the air capable of spreading flames or explosions, in %uel. For different gases, the lower explosion limit of gas is different, for example, the lower explosion limit of methaneCH4 is 5%vol, and the lower explosion limit of hydrogen is 4%vol.
Therefore, whenmethanegas detectorWhen the concentration is displayed at 100%, it means that 100% LEL, i.e. 5% vol. has just reached the lower explosion limit and is at risk of explosion, so immediate safety measures are required.
2. catalytic combustionDetection principle
methane detector catalytic combustionDetection principle
At present, the catalytic combustion detector is mainly used for the detection of flammable gas in LEL mode, and its principle is a double bridge (commonly known as Wheatstone bridge) detection unit, in which one platinum wire bridge is coated with catalytic combustion material. Regardless of the flammable gas, as long as it can be ignited by the electrode, the resistance of the platinum wire bridge will change due to the change in temperature, and the change in temperature is directly proportional to the concentration of the flammable gas. The concentration of flammable gas can be calculated through the instrument's circuit system and microprocessor.