How to Read a 4-Gas Monitor: O2, LEL, CO and H2S Readings Explained
A 4-gas monitor shows four channels in three different units, and they are not comparable to each other. This guide reads the display field by field: the clean-air baseline, what an oxygen drop implies, why 10% LEL is not 10% gas, what the LOW, HIGH, TWA, STEL and PEAK labels mean, and which hazards the four channels cannot see at all.
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