There are many safety measures put in place to protect the workers. A lot of them are to protect you from yourself. Analyzers play a crucial and vital role in protecting workers from hazardous conditions. We have come a long way from when miners would carry a canary with them.
The most common asphyxiant in the mines was an odorless, tasteless, and highly combustible gas named methane. The canary would pass out or die and hopefully give you enough time to bail out of the situation. In the 1950's a catalytic bead detector was created. We will have two beads, one is the reference and the other is the measure or active bead. The active bead is made of a small coil of platinum wire embedded in a bead (typically alumina) that is coated with a palladium or rhodium catalyst. The catalyst coating helps the oxidation of combustiblesgases. The reference bead is made the same but it has an inert coating which makes it not react with anything. The two coils are then heated by passing current through them until they are at a temperature where the active bead is effective at oxidizing gases. As the active bead oxidizes the gas, it's temperature will rise. The difference in temperature between the active bead and the reference bead will tell us the concentration.
Industry seems to be choosing to use IR gas detection as their fixed point now days. An IR source will emit and bounce off a mirror and back to a detector. If there are no combustible gases in the IR path then 100% of the IR hits the detector. Thus the output is 0%. If gas crosses the path then it will absorb some of the IR and thus the output will go up. The more gas/the more IR is absorbed the higher the output.
What can screw up a vapor detector like a soup sandwich? That would be a spider making a home inside of it.
Can you tell me which insect causes more trouble than any other?