How to set up a mixed gas alarm
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How should a mixed gas alarm be set up? The process only provides me with the percentages of the various components in the mixture. Should I set an alarm for whichever component has a higher concentration? Do we need to see the explosion of Zha’s limits?
This must be determined based on the composition of the gas mixture. For explosive combustion, components that are lighter and have a wider explosion limit should be selected ； For those that are toxic, choose those with strong toxicity. This must be done according to the actual circumstances. Or use one set for all possible probes – it’s reliable and secure, and it also shows that your organization has the means.
For a mixture of gases, the LEL alarm threshold should be set according to the medium with the lower sensitivity. The sensitivity parameters are closely related to the composition of the medium, as well as to the design of the instrument itself; you can ask the manufacturer to provide them.
If it is to test explosiveness, then the national standards are the same. They are basically set according to the methane standard. As for the differences in various gas components, you can appropriately lower the alarm threshold based on the overall LEL. But it can’t be increased
This requires taking into account the properties of the substance being tested, such as specific gravity, flammability, explosiveness, etc., in order to determine the appropriate installation location; there are standards for this.
It’s very simple when using catalytic combustion type
This discussion is essentially such a story: Suppose there is a tank area with gasoline tanks, diesel tanks, jet fuel tanks, propane tanks, and methanol tanks – leaks can occur in any of them. So I bought a LEL gas sensor – which parameter should be used to calibrate the alarm threshold? @jiaguoyun
There is a standard, namely the one for gas alarms; I’ve forgotten the exact number. There are regulations stipulating that, for multiple types of flammable gases, the threshold is set based on the one that reaches its explosion limit first. If flammable gases are mixed with toxic gases, then the setting is determined according to the toxic gases. . . In a tank farm, there may be gasoline tanks, diesel tanks, jet fuel tanks, propane tanks, and methanol tanks, all of which could experience leaks. Then install one under each tank, set it according to the flammable gas parameters: give an alarm at 25% LEL and a high-level alarm at 50% LEL
Yes, that’s the story. But what’s the ending of the story?