>>334447I work in the sour gas fields in northern Alberta. We typically use a 4-head multi gas detector like this:
https://www.acklandsgrainger.com/AGIPortalWeb/WebSource/ProductDisplay/globalProductDetailDisplay.do?item_code=BWT135334L3&zone_id=CATZ1Dependable if bump tested regularly, easy to swap out individual heads if they malfunction and rugged for harsh environments. Pretty expensive but if you are operating in confined spaces its worth the money for your life.
Cheaper and low tech solution that you can't fuck up (no need to calibrate via bump testing) are the glass tube tests which are single use for one gas only (ie you need a different tube for each type of gas you want to sample for)
https://www.acklandsgrainger.com/AGIPortalWeb/agi/Safety/Gas-Detection/Single-Gas-Detection-Tubes/_/N-1wgj?tadsrvrk=28The most important gasses to be aware of are
Oxygen - this should be a no brainer but if you are in an oxygen deprived area for too long, you will die
Carbon monoxide - most people have these in their houses now along with fire alarms, this is what kills people when they lock themselves in the garage with a car running
Hydrogen Sulfide (H2S) -kills or causes brain damage etc. when exposed to high concentrations. Common in the sour patch up here, Farmer's Silos, Sewers, etc.
LEL - not a gas per say but most multigas monitors will detect the Lower Explosive Limit of the atmosphere you are in. Saves your ass from getting blown up by using non-intrinsically safe electronics or using a lighter, smoking etc.
Pic related, its the most common multigas detector used up here
